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Relay for thermistor protection (PTC)
Relay for thermistor protection (PTC)
These devices, commonly referred to as PTC thermistor protection relays or motor thermal protection relays, are specialized monitoring units designed to protect electric motors from overheating by continuously measuring the resistance of PTC (Positive Temperature Coefficient) thermistors embedded in the motor...
Relay for thermistor protection (PTC)
These devices, commonly referred to as PTC thermistor protection relays or motor thermal protection relays, are specialized monitoring units designed to protect electric motors from overheating by continuously measuring the resistance of PTC (Positive Temperature Coefficient) thermistors embedded in the motor windings. When the winding temperature exceeds a preset threshold, the thermistor resistance spikes, triggering the relay to open its output contacts and disconnect the motor from the supply. Typical technical parameters include rated control supply voltages (e.g., 24 VDC, 110-240 VAC), number of poles (usually 1 or 2 changeover contacts), and trip resistance values (commonly around 3.3 kΩ to 4.5 kΩ). These relays are available in modular DIN-rail mount housings for integration into control panels.
Primary applications include protection of AC induction motors, especially in pumps, fans, compressors, and conveyor systems where thermal overload is a risk. They are also used in transformers, generators, and other rotating machinery. Installation environments range from industrial automation cabinets to HVAC control panels and process control systems. The relay ensures compliance with standards like IEC 60947-8 for motor protection.
Key subcategories include single-channel and multi-channel PTC relay modules. Common article codes follow patterns such as "CM-PTC" series from ABB or "3RN1" series from Siemens, where the code often indicates the number of channels and supply voltage (e.g., 3RN1010-1CW00). Other relevant items include the "EMT6" series from Eaton and "K8AB-PM" from Omron. These codes typically encode the relay type, input voltage, and output configuration.
Our service offers express worldwide shipping and dedicated support from electrical engineers who can assist with relay selection, wiring diagrams, and integration into existing protection schemes. We provide real-time pricing and technical documentation for each article.
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