Three-phase monitoring/security relay for phase failure/asymmetry/overvoltage control

Phase protection relays are designed to protect equipment with precise operating voltage values and phase reversal functions from faults that may occur due to line voltage and motor temperature.

The FKV-24F has a constant asymmetry of 11%. It can operate at voltages from 180 to 500 VAC.

Asymmetry means the difference between the voltage values. Especially with three-phase loads such as motors, the high voltage coil consumes a high current and the low voltage coil a low voltage. Therefore, they operate unbalanced and the coils get damaged over time.

When the device is turned on, contacts 1 (NC) and 2 (COM) are closed and contacts 2 (COM) and 3 (NO) are open. If the voltage values are within the normal range, the LED (OUT) on the relay will light up; contact terminals 1 (NC) and 2 (COM) are open, contact terminals 2 (COM) and 3 (NO) are closed.

If the difference between the voltage values is greater than 11%, the relay LED goes off after about 1 second and the contacts of contactor 1 (NC) and 2 (COM) are switched on and the contacts of contactor 2 (COM) and 3 (NO) are switched off. If the difference between the voltage values decreases by 5 V, the relay LED lights up and the contacts of contactor 1 (NC) and 2 (COM) are switched off and the contacts of contactor 2 (COM) and 3 (NO) are switched on.

If the phase sequence is correct, the relay LED lights up; the contacts of contactor 1 (NC) and 2 (COM) are disconnected and the contacts of contactor 2 (COM) and 3 (NO) are switched on. If the phase sequence is incorrect, the relay LED lights up, then goes off, and the contacts of contactor 1 (NC) and 2 (COM) are energized and the contacts of contactor 2 (COM) and 3 (NO) are de-energized.

When the voltage value exceeds the high voltage setpoint, the LED for a high voltage fault (U>) lights up. If the voltage value does not drop below the normal value within 2 seconds, the device has a high voltage fault. In this position, the relay LED turns off, the contacts of contactor 1 (NC) and 2 (COM) are closed, and the contacts of contactor 2 (COM) and 3 (NO) are open. If the voltage value drops 5 V below the set high voltage point, the LED indicating the high voltage fault turns off and the device starts counting down the fault delay time (t). After the fault delay time has elapsed, the relay LED lights up, the contactor contacts 1 (NC) and 2 (COM) are open, and the contactor contacts 2 (COM) and 3 (NO) are closed.

When the voltage values fall below the low voltage setpoint, the LED for a low voltage fault (U<) lights up. If the voltage values do not rise to normal during the fault delay time, the device has a low voltage fault. In this state, the relay LED turns off, its contactor terminals 1 (NC) and 2 (COM) are closed, and its contactor terminals 2 (COM) and 3 (NO) are disconnected. If the voltage value exceeds the low voltage setpoint by 5 V, the LED indicating the low voltage fault turns off and the device starts counting down the fault delay time (t). Once the fault delay time has elapsed, the relay LED lights up and the contacts of contactor 1 (NC) and 2 (COM) are disconnected and the contacts of contactor 2 (COM) and 3 (NO) are closed.

Key features:

Operating voltage (Un): 3x380 VAC

Operating frequency: 50/60 Hz.

Operating power: <4 VA

Operating temperature: -20 °C to 55 °C.

Low voltage: 180 VAC (fixed)

High voltage: 500 VAC (fixed)

Asymmetry: ~%11 (fixed)

No neutral conductor: yes

Indication: 5 LEDs

Contact: 5A / 250 VAC active load

Cable diameter: 2.5 mm2

Weight: <110 g.

Mounting on DIN rail.