Thermochromic overtemperature indicators can be employed in several critical areas, such as the insulation of electrical cables and connectors. Image courtesy of IRISS, Inc.
Using thermochromic overtemperature indicators for detecting fire risks in electrical equipment.
By Josh Robinson, Global Service Director, IRISS, inc.
The detection of overheating in electrical systems is crucial for preventing failures, ensuring safety, and maintaining the longevity of equipment. Overheating can lead to catastrophic consequences, including equipment damage, fires, and costly downtime. Traditional methods of monitoring the temperature of electrical systems often rely on complex instrumentation, such as thermography cameras.
Thermography inspections are very effective, and in many circumstances are mandated by the National Fire Prevention Association’s standard NFPA 70B. But even the most comprehensive inspection program might not pick up an intermittent overtemperature event. There can also be a long wait between inspection cycles, which means overtemperature events can be left undetected for quite some time.
An alternative and innovative real-time approach to temperature monitoring involves the use of thermochromic overtemperature indicators that change color in response to temperature variations. This color change provides a simple visual indicator of an overtemperature event that anyone, whether trained in thermography or not, can immediately recognize.
This article explores the use of thermochromics in detecting overheating in electrical systems, discussing their application, advantages, and implementation considerations.
THERMOCHROMIC OVERTEMPERATURE INDICATORS
Thermochromic overtemperature indicators offer a visually intuitive method for detecting temperature changes, making them particularly useful in environments where simplicity and immediate feedback are essential. These indicators can be applied in various forms, such as cable clips, paints, or self-adhesive labels and wraps. The primary principle behind thermochromic overtemperature indicators is that their chemical composition changes with a rise in temperature, leading to a shift in the wavelengths of light they absorb and reflect. This change manifests as a visible color shift, providing a clear and instant indication that the temperature has exceeded a certain threshold.
Thermochromic overtemperature indicators are easy to install on equipment. Cable clips, which come in a variety of sizes to fit different sizes of cable and can be applied easily by hand. Likewise, self-adhesive cable wraps are applied with a strong self-adhesive directly onto the equipment to be monitored. Possibly the most versatile option is thermochromic paint, which can be applied directly to any clean surface and changes color vividly due to an overtemperature event.
CRITICAL AREAS TO MONITOR
In electrical systems, thermochromic overtemperature indicators can be employed in several critical areas. For instance, they can be applied to the insulation of electrical cables and connectors. Cables that carry high currents are particularly prone to overheating due to resistive heating or a bad terminal connection. When the temperature of a cable exceeds a safe limit (such as 70°C or 90°C, for example) the thermochromic indicator will permanently change color, signaling an overheating event.
This color change is an immediate visual for technicians to inspect the system, reducing the risk of insulation breakdown, possible short circuits, or fires. Similarly, thermochromic overtemperature indicators can be used in junction boxes to monitor the temperature of electrical connections. Over time, connections may loosen or degrade, leading to increased resistance and localized heating. A thermochromic indicator can provide an early warning, allowing for timely maintenance and preventing potential failure.
Transformers and electric motors are also prone to overheating, especially in industrial settings where they operate continuously under heavy loads. Overheating in transformers can cause insulation degradation, leading to short circuits and failures, while in motors, it can damage windings and bearings, reducing efficiency and lifespan.
Thermochromic overtemperature indicators offer a visually intuitive method for detecting temperature changes. Image courtesy of IRISS, Inc.
Thermochromic paints or labels can be applied to the surfaces of transformers and motors, providing a simple and effective means of monitoring temperature. If the temperature exceeds a safe level, the indicator changes color, allowing for quick visual inspection and intervention. In addition, thermochromic labels can be placed on critical parts of these devices, such as bearing enclosures, to provide a localized temperature indication. This can help in identifying specific areas of concern, facilitating targeted maintenance and preventing more extensive damage.
Control panels and enclosures that house electrical components also benefit from the application of thermochromic overtemperature indicators. In many industrial and commercial settings, control panels are used to manage and monitor various electrical systems. These panels contain numerous components that generate heat, and overheating can lead to malfunctions or fire hazards.
Integrating thermochromic overtemperature indicators into control panels allows operators to visually monitor the temperature of internal components without the need for complex sensors or instrumentation. If the temperature rises beyond a predetermined limit, the thermochromic material changes color, alerting the operator to act. Similarly, applying these indicators to the exterior of enclosures can provide a quick visual check to ensure that internal temperatures remain within safe limits. This is particularly useful in environments where frequent physical inspections are challenging, such as in remote or hazardous locations.
THE ADVANTAGES OF THERMOCHROMICS
The use of thermochromic overtemperature indicators in electrical systems offers several significant advantages. One of the primary benefits is early detection. Thermochromic overtemperature indicators provide an immediate and easy-to-understand visual warning of overheating, allowing for rapid response and preventive maintenance. This can be particularly valuable in environments where quick action is necessary to prevent damage or ensure safety. Additionally, thermochromics are a cost-effective solution.
Compared to electronic temperature monitoring systems, thermochromic materials are generally more affordable. They do not require power, wiring, or complex electronics to function, making them easy to install and maintain. This simplicity also contributes to their reliability; thermochromic indicators are passive, meaning they do not rely on external power sources or electronic components that could fail. This makes them highly reliable and suitable for a wide range of applications.
IMPORTANT CONSIDERATIONS
There are also important considerations to keep in mind when implementing thermochromic overtemperature indicators in electrical systems. One of the key factors is the temperature range. It is crucial to select thermochromic overtemperature indicators that react within the appropriate temperature range for the specific application. Different materials have different activation temperatures, and using the wrong type could result in inaccurate or ineffective monitoring. When sourcing thermochromic overtemperature indicators, it’s best to use those that have been manufactured specifically for industrial and commercial use with an appropriate temperature range, such as 70°C or 90°C.
Durability is another important consideration. Thermochromic materials must be able to withstand the environmental conditions they will be exposed to, such as humidity, UV exposure, and mechanical wear. Finally, while thermochromics overtemperature indicators are excellent for visual indications, they only show when a temperature range has been exceeded, and they do not provide precise real-time temperature readings.
For critical applications where exact temperature monitoring is required, thermochromic overtemperature indicators should be used alongside other temperature monitoring tools to provide a comprehensive solution. A thermochromic option for this is the use of “actual temperature” labels, which operate much like a traditional thermometer, providing a real-time readout of the actual temperature of your equipment, usually within a range of 5°C.
The use of thermochromics to detect overheating in electrical systems represents an innovative approach to temperature monitoring. By providing a simple, cost-effective, and reliable method for early detection of overheating, thermochromic overtemperature indicators can enhance safety, improve maintenance practices, and prevent costly downtime. ESW
Josh Robinson is an experienced leader in Condition-Based Maintenance (CBM) and a dedicated advocate for electrical maintenance safety and reliability. With a career focused on keeping maintenance workers safe from electrical hazards, he has championed the adoption of advanced technologies such as infrared thermography, ultrasound testing, and vibration analysis to enhance safety and efficiency in industrial settings. His expertise extends to motion amplification and root cause analysis, making him a sought-after expert in predictive maintenance and strategic asset management.
He holds an MBA from Louisiana State University Shreveport and a Bachelor of Science in Business Administration from the University of South Florida Sarasota-Manatee. He is also deeply involved in innovation at IRISS, driving initiatives that push the boundaries of maintenance safety and technology.
For more information on thermochromic overtemperature indicators, and to see them in action, please visit https://iriss.com/safe-connect-thermochromic-solutions/.