Data Centres
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving data centres.
Discover MoreContactor and Relay Defects Identified by Thermal Imaging
- ✔ PCN/ITC L2+
- ✔ ISO 18434-1
- ✔ Fully insured
- ✔ UK-wide
Understanding Contactors, Relays and Control Equipment Defects
Contactors, relays, motor overload devices and electronic control equipment perform essential switching, protection and automation functions across industrial and commercial electrical systems. Thermal imaging can identify abnormal heating at connections, internal contacts, coils, resistors and printed circuit boards while equipment remains in operation.
These components may deteriorate through contact wear, frequent switching, coil ageing, winding degradation, loose or high-resistance connections, contamination, excessive load, poor ventilation or failure of electronic components. The resulting thermal pattern varies with device design and duty.
Our electrical thermal imaging surveys assess accessible control equipment under representative operating conditions. This page explains how contactor, relay and control-panel defects may appear thermally, why comparison with similar devices matters and how thermography supports planned maintenance.
The operational consequence may be disproportionate to the physical size of the component. Failure of a small contactor, relay or control-board component can stop a motor, process line, pump, HVAC system or other critical service.
Effective assessment considers the circuit load, switching duty, coil voltage, enclosure cooling, comparable phases or devices, equipment function and the consequences of failure. Thermal images direct investigation but do not replace electrical testing or functional checks.
For a wider overview, visit our Common Electrical Faults Identified by Thermal Imaging guide. Connection-related anomalies are also covered in our High-Resistance Connections guide.
Page Contents
- What Are Control Equipment Defects?
- Why Control Equipment Defects Generate Heat
- Thermal Imaging Examples
- Causes, Indicators, Equipment and Risks
- Where Control Equipment Defects Occur
- Corrective Action and Follow-Up
- Why Specialist Thermal Interpretation Matters
- Why Choose Red Current
- Industry Applications
- Frequently Asked Questions
What Are Contactor, Relay and Control Equipment Defects?
Control equipment defects include deteriorated switching contacts, abnormal coil behaviour, poor terminal connections, failed overload devices and overheating electronic components. The equipment may continue operating while thermal behaviour changes.
The source of heat can be external or internal. A contactor-to-overload interface may show localised connection heating, whereas deterioration within the contactor can spread heat through the device body.
The significance of the anomaly depends on load, switching duty, component design and the controlled process. Safe inspection and appropriate testing may be required to determine the exact cause.
Why Control Equipment Defects Generate Heat
Internal Contact Resistance
Repeated switching and contact wear can increase resistance across a contactor or relay interface, creating abnormal heating while current flows.
Coil and Winding Losses
Control coils normally generate heat, but winding deterioration, incorrect voltage, mechanical problems or prolonged energisation can produce excessive temperatures.
Electronic Component Heating
Resistors, relays and PCB-mounted components dissipate heat during operation. Excessive temperature can damage circuit boards and adjacent components if the design or condition deteriorates.
Thermal Imaging Examples of Contactors, Relays and Control Equipment
Control-equipment defects can occur across different contactor designs and within electronic relay assemblies. The four examples below add three control-coil anomalies and PCB-mounted relay resistor damage to the contactor connection and internal-contact examples shown above.
Important: Control coils normally operate above ambient temperature. A reliable assessment requires comparison with similar devices, consideration of coil voltage, duty, enclosure temperature, component design and evidence of progressive change or damage.
Control Equipment Defect Characteristics
Common Causes
- Internal contact wear
- Frequent switching operations
- Coil winding degradation
- Loose or high-resistance connections
- Incorrect or unstable coil voltage
- Poor ventilation or contamination
- Electronic component ageing
Typical Thermal Indicators
- Localised terminal or interface hotspot
- Contactor body hotter than equivalents
- Excessive coil temperature
- Uneven pole temperatures
- PCB resistor or relay overheating
- Visible thermal damage around components
Affected Equipment
- Contactors and motor starters
- Motor overload devices
- Control relays and timers
- Control coils and solenoids
- Motor control centres
- PLC and control-panel assemblies
- PCB-mounted relay circuits
Potential Risks
- Loss of motor or process control
- Nuisance operation or failure to operate
- Contact welding or arcing
- PCB and component damage
- Unplanned production stoppage
- Damage to connected equipment
- Fire risk
Concerned About Abnormal Control Equipment Temperatures?
Red Current can assess contactors, relays and control equipment under representative operating conditions, provide clear thermal and visual evidence, and deliver an independently reviewed report with prioritised recommendations.
Where Control Equipment Defects Commonly Occur
Thermal anomalies may occur within contactors, motor starters, overload units, control relays, timers, coils, solenoids, PLC panels, motor control centres and PCB-mounted relay circuits.
A localised hotspot at a terminal or contactor-to-overload interface may indicate connection resistance. Heating through the device body may instead originate from internal contacts or a control coil, while electronic assemblies can show concentrated resistor or PCB heating.
The six examples on this page span contactor connections, internal contacts, three alternative coil designs and relay-board components. Together they demonstrate why control-equipment thermography requires knowledge of component function and expected operating temperature.
Corrective Action and Follow-Up
Thermal imaging identifies contactors, relays and control equipment that warrant investigation; it does not replace safe isolation, electrical testing or functional checks. Corrective action may include checking terminals, testing coil voltage, replacing worn contactors or relays, addressing ventilation, repairing damaged PCB assemblies or reviewing switching duty.
Where practicable, a follow-up thermal inspection under comparable operating conditions can help verify that corrective work has resolved the abnormal pattern. Repairs should be completed by appropriately competent personnel and in accordance with manufacturer requirements.
Need a Survey or Independent Verification?
Red Current can provide a specialist electrical thermal imaging survey or follow-up verification inspection under representative operating conditions. Our electrically qualified, ITC/PCN certified thermographers provide clear thermal and visual evidence, independently reviewed reporting and prioritised recommendations, while your electrical contractor or controls specialist remains responsible for testing and remedial work.
Why Specialist Thermal Interpretation Matters
Control Coils Normally Generate Heat
An energised coil can operate warmer than surrounding components. The assessment depends on comparison, duty, voltage, device design and evidence of deterioration rather than temperature alone.
External and Internal Sources Look Different
Connection heating is often concentrated at an interface, while internal contacts or coils can heat a broader area of the device body. Understanding construction helps locate the likely source.
Electronic Boards Require Component-Level Context
PCB-mounted resistors and relays can run hot by design, but excessive or uneven temperatures combined with visible damage may indicate an unacceptable condition.
Interpretation and Reporting Create the Value
The value of control-equipment thermography lies in converting thermal evidence and operational context into a defensible maintenance decision. Red Current’s assessments draw on electrical expertise, ITC/PCN certification, structured review and an in-house knowledge base developed from years of reporting data and millions of thermal images.
Specialist Support for Electrical and Controls Companies
Red Current can provide specialist thermal inspection, analysis and reporting while the electrical contractor or controls specialist retains responsibility for functional testing and remedial work.
Why Choose Red Current for Electrical Thermography?
Realising the full value of an electrical thermal imaging survey depends on the competence of the thermographer, the quality of the inspection process and the clarity of the final report. Red Current combines electrical knowledge, certified thermography expertise and structured quality assurance to provide findings that can be understood, prioritised and acted upon.
Qualified Thermographers
Our electrical thermal imaging surveys are undertaken by electrically qualified, ITC/PCN certified thermographers. These recognised certification schemes provide structured training and assessment in infrared thermography, while our electrical qualifications and field experience support safe, technically informed inspection of live electrical systems. Thermographer competence matters because image capture, measurement, interpretation and reporting must be considered together.
Read more about why ITC/PCN thermography certification and surveyor competence matter.
ISO-Aligned Survey and Reporting
Our survey and reporting processes are aligned with ISO 18434-1, supporting a consistent approach to inspection, analysis and communication of findings. Reports are prepared to give maintenance teams clear evidence, appropriate context and practical priorities.
See our guidance on electrical thermal imaging standards, reporting and survey requirements.
Reviewed, Actionable Reporting
Thermal images alone do not provide a maintenance strategy. Our reporting process turns observations into documented findings with supporting thermal evidence, priority classifications and recommendations that can be used by facilities teams, insurers and electrical contractors.
Find out whether an electrical thermal imaging report can support insurance requirements.
Experience Across LV and HV Systems
Control equipment ranges from compact relays and PCB assemblies to contactors, overload units and motor control centres. Red Current delivers electrical thermography across commercial and industrial environments, helping ensure each anomaly is assessed in the correct load, duty and process context.
Explore our common electrical faults guide and high-voltage thermal imaging surveys.
Specialist support without competing for remedial work: Red Current can provide the thermographic survey, analysis and report while the client’s appointed electrical contractor or in-house electrical team completes any required investigation and remedial work.
Industries Affected by Control Equipment Defects
Contactor, relay and control-equipment defects can affect every sector that relies on motors, pumps, conveyors, HVAC, automation or process-control systems.
Manufacturing Facilities
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving manufacturing facilities.
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High Voltage Substations
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving high voltage substations.
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Hospitals & Healthcare Facilities
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving hospitals & healthcare facilities.
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Distribution Centres
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving distribution centres.
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Food Manufacturing Facilities
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving food manufacturing facilities.
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Commercial Offices
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving commercial offices.
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Schools, Colleges & Universities
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving schools, colleges & universities.
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Shopping Centres & Retail Parks
Thermal imaging can identify developing contactor, relay and control-panel issues within electrical systems serving shopping centres & retail parks.
Discover MoreFrequently Asked Questions
Possible causes include worn internal contacts, high-resistance connections, excessive switching, coil winding degradation, incorrect coil voltage, contamination, poor ventilation and component ageing.
Abnormal heating through a contactor body or across one pole can indicate deteriorating internal contacts, but load, device design and follow-up electrical testing must also be considered.
No. Energised coils normally generate heat. Concern arises when the temperature is excessive relative to comparable devices, inconsistent with duty or voltage, increasing over time or associated with visible deterioration.
Yes. The interface can develop increased resistance and localised heating. Safe isolation and physical inspection may be required to confirm the cause.
Thermography can identify excessive heating at resistors, relays and other electronic components. Visible board damage and functional testing provide additional evidence.
Yes. Failure of a contactor, relay, overload unit or control-board component can interrupt motors, pumps, conveyors, HVAC and automated processes.
Priority considers thermal behaviour, component function, load, duty, process criticality, visible damage, likely failure mode and consequences of loss of control.
Specialist thermographers interpret connection, contact, coil and PCB patterns alongside equipment design and operating context, then provide consistent reporting and actionable recommendations.
For broader survey questions, visit our Electrical Thermal Imaging Survey FAQs.
Small Control Components Can Have Major Consequences.
Contactors, relays and electronic control components may be physically small, but their failure can interrupt important plant and building systems. Representative operating conditions, device knowledge, comparative analysis and appropriate follow-up testing are essential if thermal findings are to support sound maintenance decisions.
Red Current provides specialist electrical thermography for end users, facilities teams, insurers and electrical testing companies throughout the UK. Contact us to request pricing, obtain a sample report or discuss a subcontract survey requirement.
