Microprocessor phase failure and asymmetry sensor CZF-B-TRMS

Microprocessor-controlled phase loss and asymmetry sensor CZF-B-TRMS is a device designed to protect three-phase powered electric motors. Its function is to detect voltage loss in any phase or voltage asymmetry between phases, which could lead to motor damage. This sensor is mounted on a DIN rail and uses True RMS voltage measurement to ensure accurate operation even in disturbed power networks.

Application and operation

CZF-B-TRMS reacts to irregularities in the power supply, such as the loss of one phase or uneven phase-to-phase voltages. If such a situation is detected, the circuit is disconnected with a 4-second delay. This delay is designed to avoid accidental motor disconnection during momentary voltage drops. Once the voltage stabilizes – increases by 5V above the trigger threshold – the motor will be automatically switched on again. During a failure, the relay contact is open, preventing the motor from starting.

Construction and characteristic features

The device has one normally open contact (1NO) and is equipped with screw connections for electrical wires. The voltage measurement range is from 140 to 270 V, making it compatible with most standard three-phase installations. The sensor does not require an external power source and is characterized by compact dimensions – 90 mm high and 65 mm deep, occupying only 2 modules on a 35 mm rail. The built-in phase asymmetry control effectively protects against overloads resulting from uneven phase loading. Thanks to the use of the True RMS method, the sensor provides accurate measurements even in the case of non-linear voltage waveforms, which is particularly important in installations with electronic loads.

Additional information

• The sensor has green LEDs indicating the power supply status.
• The maximum relay contact load current is 10 A.
• The operating temperature of the device is in the range of -25°C to 40°C.
• The IP20 protection class provides protection against touching with a finger and solid objects larger than 12.5 mm.
• The voltage asymmetry trigger value is 55V, and the voltage hysteresis is 5V.