Control Panel Engineering
Control Panel Cooling: Why Adding a Fan Isn't Always the Answer
Understanding heat loads, airflow, ambient temperatures, and why the right cooling solution starts with understanding where the heat goes.
A fan can move air inside a control panel, but it cannot make heat disappear. Reliable thermal management starts by estimating how much heat the equipment produces, understanding where that heat can go, and selecting a method that still works at the worst expected ambient condition.
The real problem is heat flow, not fan count
VFDs, power supplies, PLCs, industrial computers, transformers, contactors, and communication equipment all convert part of their input energy into heat. In a densely packed or sealed enclosure, that heat raises the internal air temperature and can create much hotter local zones around major heat producers. For a water or wastewater facility, high room temperature, outdoor sun, a loaded process, or a clogged filter can turn a panel that normally runs well into a summer reliability problem.
Internal circulation
A circulation fan can reduce hot spots, improve temperature distribution, and move heat toward enclosure surfaces or cooling equipment. It does not independently remove heat from the enclosure.
Ventilation
A filtered fan can carry heat out only when the incoming air is cool enough and acceptable to bring into the enclosure.
Closed-loop cooling
A heat exchanger or air conditioner keeps internal and external air paths separate, helping preserve enclosure protection in dusty, oily, or wet environments.
Start with a heat-load inventory
For each component, use the manufacturer's published power-loss or heat-dissipation value at the expected load and duty cycle. Do not treat the connected load as though all of it becomes heat inside the panel. Most power passing through a VFD is delivered to the motor; only the drive's losses are dissipated as heat inside the enclosure.
- List every heat-producing device inside the enclosure.
- Record the loss in watts at the expected operating point, including duty cycle, loading, and simultaneous operation.
- Add the losses to obtain the internal heat load in watts.
- Convert the result to BTU/h when cooling equipment is rated in those units.
BTU/h is a rate of heat transfer. It gives the electrical designer and cooling supplier a common basis for comparing panel heat generation with cooling capacity. It is not the only sizing input.
Engineering Example: heat load
Assume a 10 kW VFD delivers its rated output at 97% efficiency. An early estimate of its loss is:
Add 40 W for a power supply, 20 W for PLC and I/O hardware, and 10 W for other devices. The total preliminary internal heat load is 379 W, or approximately 1,293 BTU/h.
This is an optional screening example. Actual equipment losses should come from manufacturer data at the expected load and operating conditions.
Engineering Example: ventilation airflow
When ventilation is appropriate, a simplified relationship connects heat load, allowable temperature rise, and required delivered airflow:
CFM means cubic feet per minute. This is an approximate delivered-airflow requirement under simplified, near-standard-air-density conditions. Filters, pressure losses, altitude, inlet and outlet geometry, and installation details can reduce actual airflow, so a fan's free-air rating is not the same as installed performance.
This brief example does not separately account for heat rejected through enclosure walls or additional solar gains. Ventilation also cannot cool the panel below the incoming-air temperature.
Then account for the enclosure and its environment
The enclosure skin may reject heat or absorb it. Its effect depends on exposed surface area, material and finish, mounting arrangement, insulation, ambient temperature, and the target internal temperature. An outdoor panel also needs a solar-load evaluation. A wall-mounted cabinet cannot use the covered surface as though it were fully exposed to room air.
Maximum ambient
Use the sustained worst-case temperature at the enclosure location, including seasonal, process-related, and solar-heating peaks.
Allowable internal temperature
Use the lowest applicable temperature limit among the installed components, with an engineering margin appropriate to the application.
Contamination and enclosure rating
Dust, oil mist, washdown, humidity, and corrosive material can rule out open ventilation even when the temperature difference looks favorable.
Installation details
Blocked inlets, loaded filters, poor component spacing, short-circuited airflow, altitude, and nearby heat sources can reduce real performance.
Component placement can create hidden hot spots
Equipment arrangement matters even when the cabinet's average temperature appears acceptable. A VFD can discharge heated air directly toward a PLC, power supply, or communications device mounted above it. That upper device may operate in preheated air while a sensor elsewhere reports a normal-looking temperature.
Follow manufacturer clearances and airflow orientation, keep ventilation openings clear, and provide a path for hot exhaust to reach the return or heat-rejection device without recirculating into an equipment inlet. A circulation fan should support that path rather than simply stir air around obstructions.
Read the airflow path, not only the thermometer
Heat-producing devices need clear intake and exhaust paths. Spacing, enclosure geometry, fan direction, and nearby obstructions determine whether cooler air reaches a PLC or whether VFD exhaust circles back through the cabinet.
The illustration is a thermal-analysis example, not a universal panel layout. Final clearances and mounting orientation must follow the installed equipment manufacturers.
Plan for year-round thermal management
Outdoor municipal panels may see high summer ambient temperatures plus direct sunlight, so cooling must be evaluated at the location's realistic worst case. Ventilation cannot produce an internal temperature below the incoming air temperature, and both heat-exchanger and air-conditioner performance must be checked at the actual indoor and outdoor conditions.
Winter introduces a different limit. PLCs, displays, batteries, drives, and other devices may have minimum operating temperatures. A thermostatically controlled enclosure heater can keep equipment above those limits and reduce the risk of condensation during cold starts or rapid weather changes.
Heating and cooling controls should be coordinated so they do not fight each other. Setpoints, dead bands, alarms, drain or condensate provisions, and seasonal maintenance all belong in one thermal plan that covers the complete operating environment.
Choose the method that matches the physics
| Method | Good fit | Main limitation |
|---|---|---|
| Passive surface dissipation | Low heat load, adequate exposed area, and ambient temperature safely below the allowable internal temperature | Capacity is limited and strongly affected by cabinet size, mounting, and ambient conditions |
| Filtered ventilation | Clean ambient air that is cooler than the desired panel temperature | Cannot cool below ambient and introduces outside air; filters add maintenance and airflow resistance |
| Air-to-air heat exchanger | Dirty ambient conditions where outside air is cooler than the desired panel temperature and closed-loop separation is needed | Performance depends on temperature difference; it cannot provide refrigeration below ambient |
| Enclosure air conditioner | High ambient temperature, need for below-ambient cooling, or a sealed recirculating air path | Requires condensate, power, mounting, and maintenance planning; actual capacity changes with rating conditions |
| Air-to-water heat exchanger | High heat loads where suitable plant water is available and room heat rejection is undesirable | Requires acceptable water quality, temperature, flow, piping, and leak-risk planning |
A practical decision boundary
If the maximum ambient temperature is already at or above the desired internal temperature, a fan or air-to-air heat exchanger does not have the temperature difference needed to solve the problem. Refrigerated or water-based cooling may be required.
If ambient air is cool enough but contaminated, a closed-loop heat exchanger may reject heat without bringing that contamination into the cabinet. Final selection should use performance data at the actual internal and external temperatures.
Practical checks before releasing the panel design
Verify the numbers
- Use manufacturer heat-loss data at expected load.
- Include simultaneous duty and future additions.
- Check cooling ratings at actual operating conditions.
Verify the airflow
- Keep inlets and outlets clear.
- Separate supply and return paths.
- Do not direct one device's hot exhaust into another device's inlet.
Verify the environment
- Document heat, cold, humidity, dust, oil, washdown, altitude, and sun exposure.
- Protect the required enclosure rating.
- Consider condensation during cooling, cold starts, and shutdowns.
Verify maintainability
- Provide access to filters and heat exchangers.
- Monitor high temperature or cooling failure where downtime matters.
- Put filter, coil, heater, and thermostat checks into preventive maintenance.
How can BEA help?
BEA can help municipal and industrial teams review component losses, enclosure construction, ambient conditions, airflow paths, and cooling options before heat becomes a reliability problem. For new designs or recurring high-temperature faults, we can help turn equipment data and field measurements into an application-specific thermal-management plan.
SSL-VPN vs. Zero Trust: Safer Remote Vendor Access for Industrial Systems
INDUSTRIAL CYBERSECURITY | SCADA | REMOTE ACCESS
Controlling what a vendor can reach matters more than the name of the technology used to connect.
Remote access can shorten downtime and bring the right specialist into a troubleshooting session without waiting for travel. That matters when a water treatment plant loses communications at 2:00 AM, a wastewater facility needs help with a PLC fault, or a manufacturer needs specialized support for a drive or analyzer.
The security question begins after the connection is established: once someone connects, what can that person or remote computer actually reach?
SSL-VPN: Flexible network access that depends on policy
An SSL-VPN, typically implemented with modern TLS encryption, creates an encrypted session between a remote user and a network gateway. After authentication, the gateway and surrounding network controls determine which routes, addresses, and services are available.
This model can fit industrial tools that expect direct IP connectivity. For example, engineering software may need to communicate with a controller through specific TCP or UDP ports and supporting services. A properly configured VPN can provide that path without changing the engineering application.
Operational strength
Protocol flexibility
Network-level connectivity can support legacy and specialized programming or diagnostic workflows when routing and firewall policies are designed for them.
Primary risk
Excessive reach
A vendor who needs one workstation may receive access to a full automation subnet containing PLCs, SCADA servers, drives, switches, and gateways.
Key control
Restrictive policy
Routes, firewall rules, access control lists, schedules, and segmentation can limit a VPN identity to required destinations and services.
Broad access is not an inherent requirement of SSL-VPN technology. It is a configuration and architecture problem. A compromised vendor laptop or stolen credential can inherit only the permissions that the environment grants, whether those permissions are broad or narrowly scoped.
ZTNA: Resource access instead of implicit network trust
ZTNA is designed to grant access to specifically authorized resources rather than provide general network connectivity simply because a user authenticated. Policies may consider identity, authentication strength, device condition, assigned role, destination, and other context.
A contractor who needs one SCADA web interface may be allowed to reach that application without gaining the ability to scan the automation subnet or communicate directly with unrelated controllers. This reduces opportunities for lateral movement if an account or endpoint is compromised.
Traditional SSL-VPN
Key point: SSL-VPN access can be narrow or broad. The enforced network policy sets the exposure.
Zero Trust Network Access
Key point: Every additional resource requires policy that explicitly permits it.
Industrial networks change the comparison
Many business applications fit identity-based, application-level access well. Industrial automation can be more complicated. PLCs, motor controllers, analyzers, and older communication devices may not support individual identities, multifactor authentication, device posture checks, or granular authorization.
Engineering tools can also rely on multiple ports, discovery services, or communication paths that must be tested across security boundaries. A ZTNA design that works well for a browser-based SCADA interface may not support a PLC programming workflow without additional architecture.
Direct PLC access carries process risk
A controller may have no practical way to distinguish an authorized engineer from another computer that can reach its programming interface. Depending on platform and configuration, access could permit logic changes, mode changes, firmware operations, or other actions that affect the physical process.
Availability remains essential
Remote access is a support function. Normal automatic control should continue if the internet, access gateway, or cloud identity service becomes unavailable.
Compatibility must be demonstrated
Validate the actual software, protocols, ports, discovery behavior, and vendor workflow. Product-category assumptions are not a substitute for an application test.
Use an engineering workstation as a controlled access point
A practical pattern is to connect the remote vendor to a designated engineering workstation or jump host rather than expose controllers directly. The workstation contains approved programming software, drivers, and configuration tools, and its network permissions are limited to the equipment required for the task.
This concentrates software management, monitoring, backups, and maintenance procedures around a known access point. It can also separate permission to reach the workstation from permission to reach the controller network.
A jump host is not automatically secure. If it has unrestricted access to every controller and server, compromising it may still expose the full environment. Use individual accounts, appropriate authentication, controlled sessions, and firewall rules that limit the workstation to required destinations. Where practical, keep vendor access disabled until an approved support window begins.
SSL-VPN and ZTNA: Compare real configurations
SSL-VPN
Common fit
- Encrypted network connectivity with policy-based restrictions
- Often straightforward for legacy industrial protocols
- Can support MFA and centralized identity
- Requires careful routes, firewall rules, and endpoint controls
ZTNA
Common fit
- Identity and policy-based access to approved resources
- Designed to minimize resource exposure
- May evaluate device posture and contextual signals
- Requires verification of protocol and engineering-tool compatibility
Either approach
Shared engineering questions
- What becomes reachable after authentication?
- Which infrastructure and services are required?
- What fails if a gateway or identity provider is unavailable?
- Can access and changes be attributed to an individual?
Modern VPN platforms can apply many Zero Trust principles. Some ZTNA products can provide broader network-level access for applications that require it. Compare the actual access path and enforced policies, not the labels.
Restrict remote access by purpose
Scenario A
SCADA interface support
Limit the contractor to a designated SCADA workstation or web interface. Direct PLC connectivity may not be needed.
Scenario B
PLC programming support
Provide an approved engineering workstation with the required software and communication path to the affected controller only.
Scenario C
Equipment manufacturer support
Limit access to a service workstation or approved gateway that can communicate with the specific drive, analyzer, or other device.
These sessions can also need different authorization for viewing information, changing configuration, or performing work that could interrupt operations. The objective is not simply to identify who connected. It is to control what the connection permits.
MFA matters, but it is not enough
Multifactor authentication helps prevent a stolen password from being sufficient for remote entry. It does not correct excessive permissions, protect an already authenticated endpoint, or replace segmentation.
Plan for failure and emergency support
A facility should understand what happens when the internet connection fails, the VPN or ZTNA gateway is unavailable, an identity provider cannot be reached, a vendor cannot establish a session, or a security incident requires remote access to be disabled.
Local personnel should retain appropriate onsite operating and maintenance procedures. For critical systems, define how authorized emergency support will work when the normal remote-access path is unavailable. An alternate path must remain secured and controlled instead of becoming an unmonitored backdoor.
Remote-access infrastructure
Local control system
Monitoring and accountability belong in the design
Facilities should be able to determine who connected, when the session occurred, which resources were accessed, and when the session ended. Where supported and appropriate, session recording can add accountability.
Connection logs do not always show what changed inside a PLC or SCADA application. A complete maintenance record may also require controller program comparisons, configuration backups, application change logs, work notes, and verification after the session. Remote work should follow the same operational discipline as onsite maintenance.
Choose the architecture the facility can operate
A smaller municipal facility with a limited vendor group may be well served by a tightly configured SSL-VPN, MFA, a dedicated engineering workstation, and restrictive firewall policy. A larger organization with many vendors and facilities may benefit from centralized ZTNA policy and granular identity-based controls. A hybrid design can also be appropriate.
Security
What resources become reachable, and what prevents lateral movement?
Compatibility
Does the design support the real programming and diagnostic tools?
Reliability
What happens when connectivity, a gateway, or authentication service fails?
Maintainability
Can local personnel understand, administer, back up, and recover the system?
Accountability
Can sessions and changes be attributed to specific individuals?
Lifecycle cost
What are the licensing, support, training, and long-term operating requirements?
Primary guidance and further reading
Foundational concepts for resource-focused access and the removal of implicit trust based on network location.
Read the NIST publication
Industrial remote-access guidance covering architecture, policy, defense in depth, and operational considerations.
Read the CISA guidance
How can BEA help?
Britton Electronics & Automation approaches industrial remote access by first understanding the facility network, the equipment requiring support, the tools used by technicians, and the consequences of remote activity.
We can help evaluate secure connectivity, firewall policy, segmentation, engineering workstation access, vendor workflows, and recovery requirements. Whether the solution uses SSL-VPN, ZTNA, or a combination, the goal is the same: provide authorized personnel with the access required for the approved work without unnecessarily exposing the rest of the operation.
Industrial Automation | Motor Control | System Design
The VFD Is Not Always the Solution
Why understanding the process matters more than adding another drive.
Variable frequency drives provide adjustable motor speed, controlled acceleration and deceleration, motor protection features, and opportunities to reduce energy use. In the right application, a VFD can deliver substantial operational and financial benefits.
But a VFD is a motor control device. It is not a substitute for understanding the mechanical equipment, electrical system, or process being controlled.
Start with the process, not the equipment
Before selecting a manufacturer or horsepower rating, ask a more important question: What are we trying to accomplish?
- Reduce energy consumption?
- Maintain pressure, flow, or another process condition?
- Limit mechanical stress or starting current?
- Improve process stability?
- Replace throttling or another inefficient control method?
These objectives do not necessarily lead to the same solution.
1. The process determines whether speed control helps
Fixed-duty transfer
A pump moving water between reservoirs at a relatively constant flow may already operate near its intended duty point. Reducing speed can increase operating time, reduce pumping efficiency, or leave too little head to complete the transfer.
Variable-demand pressure
A pressure-boosting system with large demand changes may benefit from adjusting pump speed to maintain discharge pressure instead of running continuously at full speed and throttling the discharge.
The key distinction
The motor may be similar in both examples. The process objective, system curve, and operating conditions determine whether variable speed creates value.
2. Energy savings are not automatic
For centrifugal pumps and fans in systems dominated by friction losses, the affinity laws are a useful approximation.
Changes approximately in proportion to speed.
Changes approximately with the square of speed.
Changes approximately with the cube of speed.
Under suitable conditions, reducing speed to 80 percent can reduce power demand to about 51 percent of the original value. That does not mean every pump at 80 percent speed will use 49 percent less energy to complete the same work.
3. Check the motor and mechanical load
Motor suitability
A pulse-width-modulated drive output can create electrical and thermal conditions that differ from across-the-line operation. Review insulation condition, voltage rating, cable length, switching characteristics, output filtering, bearing currents, shaft grounding, thermal protection, and the torque required across the speed range.
Cooling at low speed
A shaft-mounted fan slows with the motor. An application that needs substantial torque at reduced speed can generate significant heat while receiving less cooling airflow. An existing motor that has run reliably for years is not automatically suitable for every variable-speed duty.
Equipment operating limits
Pumps, fans, blowers, conveyors, and positive-displacement equipment each have operating limits. Minimum flow, preferred operating region, lubrication, cooling, starting torque, unstable regions, and discharge pressure remain mechanical and process constraints. The drive cannot eliminate them.
4. Electrical system compatibility matters
Adding a VFD changes how the motor interacts with the electrical system. Power electronics, switching frequencies, control circuits, and heat introduce installation requirements that a conventional starter may not have.
- Input harmonics and power quality
- Available fault current and short-circuit ratings
- Grounding and electromagnetic interference
- Input reactors, DC chokes, and output filters
- Motor lead length and reflected-wave effects
- Enclosure ventilation and heat dissipation
- Environmental conditions and enclosure ratings
- Protection and coordination with upstream equipment
5. More control is not always better control
Discrete control may be enough
If a transfer pump only needs to maintain a tank between established high and low levels, an across-the-line starter with appropriate level controls may perform reliably. Adding analog feedback and a PID loop might provide little additional value.
Continuous modulation may be essential
A system that must hold stable pressure across widely varying demand may benefit substantially from variable-speed control. Here, continuous modulation directly supports the process objective.
Complexity needs a reason
Every added control variable brings parameters, troubleshooting considerations, and possible failure modes. Complexity should be justified by a measurable operational benefit, not by the number of features available.
6. Reliability and maintainability belong in the decision
VFD troubleshooting can involve parameters, fault history, communications, control logic, power quality, motor characteristics, and the mechanical load. Replacement may also require matching capabilities, restoring parameters, configuring communications, and verifying operation.
For critical infrastructure, consider local parts availability, technician familiarity, replacement lead times, documentation, spare strategy, and the consequences of downtime. Sophisticated equipment is only an improvement if the organization can support it through the full service life.
7. Evaluate complete lifecycle cost
Installed cost
Include the drive, enclosure, electrical and mechanical modifications, engineering, programming, commissioning, and any required filters or cooling.
Operating value
Evaluate energy under actual conditions, process stability, productivity, reduced wear, avoided downtime, and other benefits that can be measured.
Support cost
Include maintenance, training, replacement, spares, expected service life, and the risk associated with component lead times.
Variable-demand applications can justify the investment quickly. Fixed-duty applications may have limited or no payback. In some cases, a soft starter supplies the desired reduction in starting stress without adding continuous variable-speed control.
8. When a VFD is the right answer
Variable-demand pumping
Maintain pressure or control flow as system demand changes, within the pump and system operating limits.
Fans and blowers
Adjust output to process demand instead of wasting energy through unnecessary throttling, where the equipment and system characteristics support it.
Process control
Maintain conditions that genuinely require continuous speed adjustment.
Controlled acceleration
Reduce mechanical stress when adjustable starting and stopping ramps provide a meaningful benefit.
Coordinated motion
Match speed between conveyors or other mechanically related equipment.
9. A practical selection checklist
- Define the process objective and how success will be measured.
- Review the load profile, system curve, static head, and required operating range.
- Confirm the motor and driven equipment are suitable across that range.
- Evaluate electrical compatibility, cable length, power quality, heat, and protection.
- Compare a VFD with a starter, soft starter, valve or damper change, mechanical repair, and control-strategy alternatives.
- Calculate lifecycle value using real duty cycles, not a single reduced-speed data point.
- Plan commissioning, documentation, spares, training, and long-term support.
Good engineering starts by understanding the process, identifying the actual problem, comparing available solutions, and choosing the approach that delivers the best overall result. The goal is not to install more automation. The goal is to make the system work better.
How can BEA help?
Britton Electronics & Automation evaluates motor control as part of the complete operating system: process requirements, mechanical equipment, electrical infrastructure, operating conditions, maintenance capability, and long-term cost.
Whether the best fit is a VFD, soft starter, conventional motor starter, or a revised control strategy, BEA can help assess the application, engineer the system, commission the equipment, and document it for future support.
Explore BEA variable frequency drive startup and support services
Sensor Selection: Picking the Right Tool for the Harsh Environment
Sensor selection often looks simple on paper. Define the range, output, supply voltage, and accuracy, then find a device that checks those boxes. That may identify a sensor capable of measuring the process, but it does not prove that the sensor is right for the application.
A device that works during commissioning can become unreliable after months of condensation, foam, buildup, vibration, sunlight, freezing weather, chemical vapors, or high-pressure washdown. The measurement requirement is only part of the specification. The environment is part of the specification too.
Start with the process, not the sensor
Before comparing devices, BEA defines what the measurement must accomplish. Is the signal used for indication, alarming, control, batching, inventory, or shutdown? How quickly does the process change? What happens if the reading is briefly wrong? What happens if it disappears completely?
Those questions establish the level of accuracy, response, diagnostics, and redundancy that the application actually needs. They can also reveal that continuous measurement is unnecessary. In some duties, a carefully applied discrete switch is simpler and more dependable than a continuous transmitter.
Measurement purpose
Define the process variable, usable range, required response, and how the PLC or operator will use the signal.
Consequence of error
Distinguish a minor indication problem from a condition that can overflow a tank, damage equipment, interrupt production, or create a safety concern.
Useful performance
Match accuracy and resolution to the process. Repeatability, survivability, and maintainability often matter more than laboratory-level precision.
The environment changes everything
Environmental conditions are not secondary details. They determine construction materials, enclosure and connection methods, mounting, protective measures, and the maintenance plan.
Moisture and condensation
Moisture can travel through connectors, junction boxes, conduit, vents, and damaged cable jackets. Temperature cycling may create condensation inside equipment that appears sealed. Enclosure rating, cable entry, orientation, drainage, and connector selection all matter.
Chemical exposure and corrosion
Wastewater gases, chlorine environments, cleaning compounds, process vapors, and treatment chemicals can attack housings, seals, diaphragms, cables, connectors, and mounting hardware. Compatibility must cover every exposed component, not only the sensing element.
Temperature
Ambient and process temperature are separate limits. Steam, nearby equipment, direct sunlight, rapid cycling, and winter conditions can affect electronics and measurement behavior even when the nominal process temperature looks acceptable.
Vibration and mechanical stress
Pumps, piping, conveyors, machinery, tanks, and flexible structures can transmit vibration that never appears in the process specification. Rigid mounting, cable support, strain relief, and connector retention may be as important as the sensing technology.
Washdown and contamination
Hot water, pressure, detergent, sanitizer, product buildup, and repeated thermal cycling can expose weaknesses beyond a basic IP or NEMA rating. Housing shape, crevices, cable routing, mounting surfaces, and cleaning practice require review.
Accessibility and maintenance
A device that needs periodic cleaning or adjustment should not require scaffolding, confined-space entry, a shutdown, or major disassembly for every service visit. Maintainability is part of selection.
Ultrasonic or radar for level measurement?
Ultrasonic and radar are both strong non-contact level technologies. Neither is universally better. The right choice follows the material, vessel, atmosphere, mounting options, reliability target, and expected maintenance.
Ultrasonic
Ultrasonic measurement can be economical, straightforward to install, and effective in many clean or moderately difficult applications.
- Check for foam, heavy condensation, steam, turbulence, and acoustic interference.
- Review narrow vessels, obstructions, and poor mounting geometry.
- Consider changes in the air space and temperature along the sound path.
Radar
Radar is less dependent on air conditions and can perform well around vapor, temperature changes, and difficult atmospheres found in wastewater and chemical service.
- Select the antenna and frequency characteristics for the application.
- Review internal structures, false reflections, and mounting geometry.
- Account for buildup and, where relevant, materials with very low dielectric properties.
Wastewater is hard on instrumentation
Wet wells, lift stations, chemical tanks, sludge tanks, open channels, water towers, and treatment basins combine conditions that challenge sensors and wiring. Humidity, corrosive gases, foam, grease, solids, turbulence, ragging, insects, debris, flooding, and difficult access may all occur at the same site.
Outdoor stations add heat, cold, lightning, and electrical disturbances. A clean wet well during commissioning is not representative of that wet well several years later. Equipment should be selected with the expectation that the environment will eventually be less clean, less accessible, and less predictable than it was on startup day.
Washdown applications test the complete installation
Food processing and similar production areas can destroy equipment that otherwise appears suitable. The installation may see hot water, pressure, caustic cleaners, detergents, sanitizer, and rapid thermal cycling several times each week or even each shift.
A stainless steel sensor is not a complete washdown solution by itself. The connector, cable gland, junction box, cable jacket, mounting surface, and cable route must also tolerate the cleaning method and chemicals. Hygienic design and material compatibility should be evaluated across the whole installation.
Mounting can matter more than the datasheet
Many apparent sensor failures begin as installation problems. A good sensor in a bad location is still a bad measurement.
Level
An ultrasonic sensor can see tank walls or an agitator. Radar can be mounted above an internal obstruction. Both cases can produce false or unstable returns.
Pressure and flow
A pressure transmitter may trap air or sediment. A flowmeter may lack the pipe conditions its measurement principle requires. Process taps and orientation affect the result.
Temperature and presence
A temperature sensor can measure ambient conditions instead of the process. A photoelectric sensor can face changing sunlight. A proximity sensor can become buried under product buildup.
Mechanical details
Unsupported cable, poor strain relief, and vibration at a connector can cause intermittent faults that look like electronic failures.
BEA considers geometry, access, wiring, obstructions, and maintenance during selection, not after the sensor has already been purchased.
Electrical and controls compatibility
The sensing principle is only one part of the system. The output and power requirements must fit the available control platform, distance, environment, and support plan. Common choices include 4-20 mA, 0-10 V, discrete or pulse outputs, IO-Link, HART, and industrial network interfaces.
The review should cover available PLC input types, resolution, isolation, shielding, grounding, cable length, power supply capacity, and surge protection. A mismatched interface can add converters, special modules, programming, and spare-parts burden. Where the application allows it, a simpler interface can improve long-term supportability.
Accuracy is not the only number that matters
Accuracy deserves attention, but it does not describe how a device will behave in the complete installation. Compare the specifications that can affect real performance and service life.
Measurement behavior
Repeatability, resolution, response time, long-term drift, minimum sensing distance, dead band, and beam angle.
Process survival
Operating temperature, pressure rating, wetted-material compatibility, enclosure rating, and shock and vibration limits.
Electrical fit
Supply range, electrical loading, output behavior, cable requirements, connector system, grounding, and diagnostics.
The most accurate sensor on paper can perform worse than a slightly less accurate device that is better suited to the environment and mounting conditions.
Failure mode matters
Selection should include a plan for bad data and complete failure. Does the signal fail high or low? Can the PLC distinguish an instrument fault from a valid process condition? Is a diagnostic output available? Can an alarm detect a frozen or stale reading? Will an operator recognize an unrealistic value?
Where the consequence justifies it, continuous tank level may be backed up by an independent high-high or low-low switch. The backup should be selected and tested as its own protection layer. Reliability comes from the complete measurement strategy, not only the primary sensor.
Standardization versus application fit
Standardization has real value: common spares, familiar programming, fewer configuration tools, easier troubleshooting, reduced inventory, and more consistent training. A preferred family is a sensible starting point.
It should not become an absolute rule. If chemistry, temperature, geometry, response, diagnostics, or maintainability make the preferred device a poor fit, the application provides a sound reason to deviate. Standardize where it makes sense. Deviate when the application gives you a good reason.
Supportability is part of the design
A device may stay in service for five or ten years. Manufacturer stability, availability, replacement lead time, distribution, documentation, spare strategy, configuration software, and replacement compatibility all affect lifecycle cost.
BEA also considers whether replacement or recommissioning can reasonably be handled by plant personnel. Instrumentation that depends on unusual proprietary hardware, undocumented settings, or scarce expertise can create avoidable risk long after installation.
Five questions before we specify a sensor
What exactly are we trying to measure?
Define the process requirement and how the signal will be used before selecting a technology.
What will the sensor actually be exposed to?
Include moisture, temperature, chemicals, vibration, washdown, foam, buildup, contamination, and abnormal events.
Where can it be mounted correctly?
Confirm geometry, access, obstructions, wiring, mechanical support, and serviceability.
How will it fail?
Decide how the PLC and operator will recognize bad, missing, frozen, or implausible data.
Can we support it ten years from now?
Consider spares, software, documentation, replacement availability, training, and maintainability.
A practical BEA selection process
Understand
Define the process, measurement purpose, range, accuracy need, response, failure consequence, and operating conditions.
Inspect
Study the real mounting location, contamination, wiring, temperature, access, geometry, and maintenance practices.
Select
Choose the technology, materials, interface, enclosure, mounting method, and protective measures for the application.
Validate
Commission under actual conditions, verify scaling and alarms, document configuration, and confirm that maintenance personnel can support it.
Reliability starts before installation
A sensor that fails repeatedly is not always a bad product. It may be the wrong technology, material, location, interface, or installation method for that environment.
BEA evaluates the process, environment, control system, mounting, maintenance requirements, failure consequences, and equipment lifecycle together. The goal is not merely to make the measurement work during startup. The goal is to install a measurement system that operators can trust after years of real-world service.
How Can BEA Help?
Britton Electronics & Automation works with industrial and municipal customers to select, install, integrate, troubleshoot, and replace instrumentation used in demanding environments.
We review the process, installation conditions, control system, wiring, mounting, maintainability, and lifecycle requirements before selecting equipment. If a measurement has become unreliable, or if you are designing a new system, we can help determine whether the problem is the sensor, the application, the installation, or a combination of all three.
Application-specific engineering, manufacturer instructions, and applicable codes should be reviewed before final equipment selection and installation.
WORKFORCE AND SUCCESSION PLANNING
The Workforce Crisis in Water and Wastewater: What Happens When Experience Retires?
A treatment plant can replace a failed component. Replacing decades of operating judgment is harder. When experienced operators, technicians and supervisors retire without a deliberate handoff, utilities lose more than headcount. They can lose the practical knowledge that connects alarms, equipment, process conditions and safe responses.
This is an operating risk, not only a hiring problem
The EPA reports that roughly one-third of the water sector workforce is eligible to retire within ten years. Utilities are also being asked to recruit, train and retain people while technology and skill requirements continue to change.
The immediate vacancy matters, but the deeper risk is knowledge concentration. If one person knows how a station behaves during a storm, where the current controller backup is stored, or why an old interlock was added, that knowledge is already a single point of failure.
What can happen when experience walks out the door?
The examples below are illustrative scenarios, not reports of specific incidents. They show how ordinary staffing gaps can become operational problems.
The alarm that does not tell the whole story
A wet-well level alarm appears during a storm. The recently retired lead operator would have checked a known sensing issue before changing pump logic. The new team sees only the alarm text and begins troubleshooting the controller. Response slows while the actual process condition continues to develop.
Knowledge to capture: alarm context, first checks, known failure patterns and escalation steps.
The restart sequence no one wrote down
After a power interruption, equipment returns in an unexpected order. A former technician knew which permissive had to be confirmed locally, but the detail never reached the procedure. Operators must reconstruct the sequence under pressure, increasing delay and the chance of an avoidable process upset.
Knowledge to capture: shutdown, transfer, restart and return-to-normal procedures.
The backup that cannot be used
A controller fails and a program backup exists, but no one on shift knows which file is current, what software version is required, or whether the replacement hardware is compatible. A file on a server is not a recovery plan unless another qualified person can find, verify and restore it.
Knowledge to capture: version records, restore steps, software access and tested spare strategy.
The workaround that became invisible
An experienced operator has compensated for a difficult valve, drifting instrument or unreliable communication link for years. The workaround leaves with that person. The next operator encounters behavior that does not match the drawings and may make a reasonable decision based on incomplete information.
Knowledge to capture: temporary practices, deferred repairs, field changes and drawing corrections.
Recruit before the vacancy becomes urgent
Recruitment works better when a utility can explain the work plainly, show candidates a credible path into the field and begin training before the only expert leaves. Water careers offer community purpose, technical variety and routes for people with mechanical, electrical, laboratory, operations, information technology and customer-service skills.
Make the work visible
Use plant tours, school presentations, job-shadow days and short employee stories to show what water professionals actually do. Connect the role to public health, environmental protection and reliable community service.
Write for candidates outside the industry
Separate skills required on day one from skills that can be learned. Replace unexplained utility terminology with clear descriptions of the work, schedule, certification path and training support. Screen for transferable ability, not only previous water-sector job titles.
Build paid entry routes
Consider apprenticeships, internships and trainee classifications that combine supervised work with structured learning. Partnerships with high schools, technical colleges, veteran organizations and workforce boards can broaden the candidate pool.
Turn mentoring into scheduled work
Do not depend on informal handoffs during spare moments. Assign mentors, name specific systems to cover, schedule field walkdowns and require the learner to demonstrate the task. Capture questions that reveal gaps in procedures and drawings.
Show a career path
Explain how an employee can progress through certification, operations, maintenance, instrumentation, controls, supervision or project roles. Visible development helps recruiting and gives current employees a reason to keep building skills.
Fix avoidable friction
Review slow hiring steps, unclear schedules, outdated job descriptions, inconsistent onboarding and tools that make routine work harder. Recruiting cannot be separated from retention. A vacancy filled today does not solve the problem if the new employee cannot succeed.
A practical 90-day starting point
- Map retirement and coverage risk. Identify roles, systems and shifts with only one qualified resource.
- List critical knowledge. Include abnormal operation, controls, instruments, vendors, backups, drawings and regulatory routines.
- Choose the first three handoffs. Pair an experienced employee with a named learner and a completion date.
- Document and demonstrate. Update the procedure, walk through it in the field, then have the learner perform or explain the task under appropriate supervision.
- Open one recruiting channel. Start a relationship with a school, workforce organization, veteran group or apprenticeship partner, and give them a clear description of the opportunity.
- Review the work environment. Ask recent hires what helped, what confused them and what nearly caused them to leave.
How can BEA help?
BEA is not a recruiting agency, but we can help utilities make technical knowledge easier to transfer and new staff easier to support. Our team can review PLC and SCADA systems, organize current program backups, improve control narratives and alarm documentation, identify obsolete or single-point-of-knowledge equipment, and support practical controls training around the systems employees use.
For utilities planning succession, a focused controls walkdown can be a useful first step. Choose one plant or station, identify what only the retiring expert knows, and turn that knowledge into documentation, training and a prioritized modernization plan.
For workforce-development ideas and federal resources, visit the U.S. EPA Water Infrastructure Sector Workforce page.
INFRASTRUCTURE RESILIENCE
Building Resilient Water Infrastructure for an Uncertain Future
Water systems are expected to run every hour of every day. Storms, power loss, aging equipment, staff turnover and cyber threats challenge that expectation. Resilience is how a system responds on its hardest day.
Resilience is not a single upgrade
No one product makes a plant or lift station resilient. Resilience comes from coordinated layers of power, local control, communications, recovery resources and trained people. Each layer should reduce the consequences when another becomes unavailable.
Start with a practical question: if this part of the system fails, what happens next? The answer should guide the design, documentation and testing.
Start with power
Every control system depends on power. Ask what happens when the utility feed drops: does the station ride through, restart cleanly, or require operator intervention? Generator transfer, UPS-backed controls and restart logic all need to match the process. A station that returns in the wrong state can create a second problem after the outage.
Check: Document the expected sequence for power loss, transfer and restoration, then verify it under an approved test plan.
Keep local control working
Design essential station control to operate without a remote server or SCADA connection. Pump alternation, backup level inputs and local alarm logic should be evaluated at the controller level. Loss of supervisory communications should not remove the local functions needed to operate safely.
Check: Define which functions continue locally and how operators recognize a communications failure.
Plan for a device failure
A resilient control design assumes a sensor or controller component may fail. Redundant level sensing, hard-wired backups and manual modes can provide additional layers when their independence and failure behavior are considered. A second sensor alone does not guarantee that a bad reading will be detected.
Check: Review sensor disagreement, backup operation and manual control while preserving required protective functions.
Give communications a backup plan
Radio, cellular and fiber links can all become unavailable. Consider more than one alarm path where the application warrants it, and examine whether those paths share power or infrastructure. Keep local control working while the link is out, and make loss of communication clear to operators.
Check: Identify who receives a lost-site alarm and what action follows.
Treat cybersecurity as another layer
Segmented networks, firewalls, controlled vendor access and tested backups each contribute to protection. Give vendors access only when needed, through a segregated path and for the authorized session. Design each layer with the assumption that another may fail.
Check: Review remote access arrangements and confirm that recovery copies are available when normal systems are unavailable.
Keep system knowledge available
Maintain current drawings, controller and HMI program backups, and network diagrams. Keep protected copies off-site and update them as systems change. Clear panel, wire and device labels help the next person troubleshoot. When experienced staff leave, the knowledge should stay with the utility.
Check: Confirm that another qualified team member can locate and understand the latest documentation.
Keep spares and test recovery
A spare is useful only if it works and fits the application. Identify critical controllers, power supplies, communication modules and HMI components, then choose spares based on operational risk and replacement lead time. Track obsolete parts and their replacement paths. Test backups and restores before an emergency.
Check: Verify that spare hardware, firmware, software and saved configurations support the planned recovery.
Modernize in stages
Replacing everything at once is rarely practical. Start with the highest-risk equipment and single points of failure. Standardize on platforms the team can support, and plan each stage to fit the next one. Temporary arrangements during an upgrade deserve the same attention as the final system.
Check: Connect each proposed upgrade to a specific failure scenario and a practical implementation sequence.
Train the people
Operators need clear procedures for abnormal conditions and manual operation. Practice outage response and recovery through planned drills suited to the site. Technology supports the response, but people must understand what the system is doing and when to intervene.
Check: Walk through responsibilities, escalation contacts and the return to normal operation.
How can BEA help?
BEA designs and supports PLC and SCADA controls for water and wastewater systems. We assess existing lift stations and plants for single points of failure, help utilities plan staged upgrades around real budgets, and document systems so the team can maintain them with confidence.
If you want a second set of eyes on your system, give us a call. Start with one station or one failure scenario, then build a practical improvement plan.
PID vs. Pseudo-Loop: Choosing How to Control the Process
A control loop should reflect the physics of the process, not just the name of the instruction. PID is an established choice for continuous regulation, but some applications benefit from an explicit step-and-wait strategy built around deadbands, timers, output increments, and exception rules. At Britton Electronics & Automation, we use the descriptive term pseudo-loop for that rule-driven approach.
What Is a Pseudo-Loop?
A pseudo-loop imitates continuous control through programmed decisions rather than proportional, integral, and derivative equations. It can use variable deadbands, variable timers, exception rules, fast overrides, preset starting points, incremental output adjustments, and conditional logic.
The deadband determines when an adjustment is needed, the increment determines how much the output changes, and the timer determines when another adjustment is permitted. Each can vary with error size, direction, equipment state, or information from another process.
Pseudo-loop is a descriptive term, not a standardized algorithm. Modern PID instructions, including enhanced controllers such as Rockwell Automation's PIDE, can also provide tracking, feedforward, limits, anti-windup, and mode management. The distinction is whether the primary regulation strategy is expressed through a tuned control equation or through explicit process rules.
Asymmetric Control: Bump Up and Bump Down
A pseudo-loop can use different adjustments in each direction. Consider a pump maintaining 60 PSI:
| Process condition | Output adjustment | Wait time |
|---|---|---|
| Below 59 PSI | Increase 2.5 percentage points | 10 seconds |
| 59–61 PSI | Hold output | No adjustment |
| Above 61 PSI | Decrease 3.0 percentage points | 10 seconds |
Illustrative settings, not recommended tuning values. Output changes are percentage points of the command range.
The larger downward step prioritizes reducing excessive pressure; the smaller upward step does not immediately undo the entire previous reduction. Combined with appropriate deadbands and waiting intervals, asymmetric adjustments can reduce hunting. They do not guarantee stability: the process response still determines appropriate increments and delays.
Near setpoint, a strategy might use smaller steps and longer waits. Farther from setpoint, it might use larger steps and shorter waits. The table shows only one band in each direction for simplicity.
Where Explicit Rules Can Help
Dead Time
In chemical dosing, a change at the injection pump may take time to reach a downstream analyzer. Repeated increases before the first change is measured can cause overdosing. A pseudo-loop can make an adjustment, wait for transport and settling time, then reevaluate. The wait can vary with measured flow. Conventional PID can also manage dead time with appropriate tuning, feedforward, or specialized compensation.
Equipment Staging
When a lag pump starts, the controller can suspend upward adjustments, select a new preset output, and change its waiting interval while header pressure stabilizes. Similar rules can respond to valve movement, backwash cycles, or demand changes.
Unreliable Inputs and Communications
A transmitter reading zero, full scale, or changing implausibly needs a defined response. Depending on the process, the controller might hold, use a validated redundant measurement, enter a restricted mode, or shut down. Loss of communications to a drive or remote I/O also needs a defined response. Holding the last output is not automatically safe.
Output Limits and Fast Overrides
If a pump reaches maximum speed while pressure remains low, further upward adjustments should not accumulate. The controller may alarm, request additional equipment, or change strategy. A high-pressure override may bypass the normal increment timer and command a larger immediate reduction, coordinated with any independent protective functions.
Transitions and Priorities
Suppose a 2.5-point upward bump is pending when a high-pressure override activates. The override takes priority; the pending bump must be canceled or explicitly suspended. When the override clears, the controller should track the actual output and deliberately resume, wait, or reinitialize. Setpoint changes, manual-to-auto transfers, and communications recovery also need defined transitions.
Windup and Output Tracking
A PID without effective anti-windup or tracking can accumulate integral error while its final output is constrained. When the constraint clears, that accumulated demand can cause an unexpected response. A pseudo-loop has no conventional integral term, but queued increments can create a similar problem. Both strategies need to cancel inappropriate adjustments, track the actual equipment command, and return to normal control under defined conditions.
Retuning and Portability
A well-structured pseudo-loop is easier to reason about. Deadbands, step sizes, and waiting intervals correspond directly to observable process behavior, so a technician can often adjust them without developing a mathematical process model. Those basic parameters can also be relatively portable between PLC platforms when scaling and execution timing are equivalent. PID parameters may differ between implementations because of equation form, time units, and scaling. Neither approach is plug-and-play: commissioning, documentation, and testing remain essential, particularly when changes affect exception priorities or equipment transitions.
Troubleshooting the Ghost Variable
A PID may calculate 65% pump speed while another routine limits the final command to 50%. Another routine may change the setpoint, and another may adjust the gains. All may be legitimate, but the technician examining only the PID cannot explain the actual pump command.
The same problem can occur in a pseudo-loop with scattered, undocumented exceptions. The important question is which routine currently owns the output, and why?
A technician should be able to see:
- Current mode and active control strategy.
- Process variable, setpoint, and error.
- Requested output and actual commanded output.
- Active deadbands, increments, and timers, when applicable.
- Output limits, overrides, and exception priorities.
- The condition responsible for the most recent output change.
Good diagnostics make the entire chain of authority visible, not just the instruction on the screen.
Choosing the Right Strategy
Conventional PID
Continuous regulation with understood dynamics, including many pressure, flow, temperature, and level applications.
Pseudo-loop
Deliberate step-and-wait behavior, independently configured upward and downward responses, significant or variable dead time, and process-specific exception handling.
Hybrid
PID performs normal regulation while supervisory logic manages staging, startup, shutdown, operating modes, and exceptions.
A hybrid design needs deliberate handoffs. When supervisory logic takes control, the PID should receive appropriate tracking or mode information so two routines do not compete for the same output.
Control the Process, Not Just the Error
PID, pseudo-loop, and hybrid control are not mutually exclusive. A facility can use each where it fits. The choice should account for dead time, interacting processes, equipment limits, abnormal conditions, and maintainability from the beginning.
The process doesn't care what the routine is named. It responds to equipment physics and the control decisions programmed around it.
How Can BEA Help?
Britton Electronics & Automation helps evaluate process behavior, define control authority, organize exception handling, improve operator visibility, and commission PID, rule-driven, or hybrid strategies. The goal is a control system that performs predictably and remains understandable to the people who support it.
Britton Electronics & Automation Inc. | Industrial Automation, System Integration & Troubleshooting
