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What do KRIWAN motor protectors do?
What do KRIWAN motor protectors do?
Kriwan motor protectors act as an intelligent safety brain for commercial HVAC and refrigeration compressors, primarily safeguarding them against catastrophic thermal overload and mechanical failure.
Unlike simple external circuit breakers that only measure current draw (amperage), a Kriwan module—such as the industry-standard Kriwan INT69 Motor Protection Relay—is wired directly to specialized positive temperature coefficient (PTC) thermistor sensors embedded deep inside the compressor’s internal motor windings.
Core Functions of a Kriwan Protector
- Winding Overheat Protection: The module continuously tracks the exact temperature of the internal electrical coils. If the motor begins to overheat due to a locked rotor, a heavy mechanical bind, or insufficient refrigerant cooling, the sensor resistance spikes instantly. The Kriwan module immediately opens its control contacts, cutting power to the main contactor to shut down the compressor before the motor windings melt.
- Dynamic Temperature Tracking: Advanced Kriwan relays do not just wait for a maximum limit to be reached. If they detect an unnaturally rapid, sudden temperature spike, they initiate an emergency shutdown immediately to prevent severe thermal stress localized to one section of the motor.
- Phase Monitoring: Many specialized models track the incoming power phases. They will trip the system if they detect a missing phase (single-phasing) or reverse phase rotation, preventing the compressor motor from running backward and destroying its internal mechanisms.
- Sub-System Supervision: Beyond temperature, modern multifunctional Kriwan modules interface with secondary sensors to monitor critical vitals like oil levels, oil differential pressure, and discharge hot gas temperatures, keeping the entire refrigeration loop under safe operating conditions.
Common Applications
You will find these German-engineered protection modules built directly into the electrical terminal boxes of large commercial scroll, screw, and semi-hermetic reciprocating compressors from major global brands like Bitzer, Copeland, and Carlyle. They act as a last line of defense to protect these high-cost assets from premature burnout.
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