Three-phase monitoring/protection relay for phase failure/overvoltage/undervoltage monitoring

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

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

Asymmetry refers to the difference in voltage values. Especially in three-phase loads, such as motors, the high-voltage winding draws a large current and the low-voltage winding draws a low voltage. As a result, they operate unbalanced and the windings get damaged over time.

When the device is switched on, the contactor 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 relay LED (OUT) illuminates; contactor terminals 1 (NC) and 2 (COM) are open, contactor terminals 2 (COM) and 3 (NO) are closed.

If the voltage difference exceeds 11%, the relay LED extinguishes after approximately 1 second, and contacts 1 (NC) and 2 (COM) of the contactors are switched on, and contacts 2 (COM) and 3 (NO) of the contactors are disconnected. If the voltage difference decreases by 5 V, the relay LED illuminates, and contacts 1 (NC) and 2 (COM) of the contactors are switched off, and contacts 2 (COM) and 3 (NO) of the contactors are switched on.

If the phase sequence is correct, the relay LED illuminates; terminals 1 (NC) and 2 (COM) of the contactors are disconnected, and contacts 2 (COM) and 3 (NO) of the contactors are switched on. If the phase sequence is incorrect, the relay LED illuminates, the relay LED extinguishes, and contacts 1 (NC) and 2 (COM) of the contactors are energized, and contacts 2 (COM) and 3 (NO) of the contactors are energized.

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

If the voltage values drop below the low-voltage setpoint, the LED indicating a low-voltage error (U<) illuminates. If the voltage values do not return to normal within the error delay time, the device has a low-voltage error. In this position, the relay LED extinguishes, contactor terminals 1 (NC) and 2 (COM) are closed, and contactor contacts 2 (COM) and 3 (NO) are disconnected. If the voltage value exceeds the low-voltage setpoint by 5 V, the LED indicating a low-voltage error extinguishes, and the device starts counting the error delay time (t). When the error delay time has elapsed, the relay LED illuminates, and contacts 1 (NC) and 2 (COM) of the contactors are disconnected, and contacts 2 (COM) and 3 (NO) of the contactors 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)

Neutral conductor absence: yes

Indicator: 5 LEDs

Contact: 5A / 250 VAC active load

Cable diameter: 2.5 mm2

Weight: <110 g.

DIN rail mounting.