Phase protection relay - FKV-24F | TENSE

The phase protection relays of the FKV series are designed to protect three-phase devices, especially motors, from faults caused by incorrect voltage values, asymmetry, phase failure, or incorrect phase sequence. The FKV-24F operates over a wide range of 180-500 VAC and has a fixed asymmetry of 11%.

It ensures reliable operation of devices with high accuracy requirements and protects them from thermal and mechanical damage.

Functions and operating principle

Voltage asymmetry (11%)

• Monitors the difference between phase voltages.

• If asymmetry exceeds 11%, the relay switches off the output after approx. 1 s and opens the NO/COM contacts.

• If the difference falls below 5 V, the relay considers the condition normal and switches the output back on after a delay.

Phase sequence check

• Correct phase sequence → LED OUT lights, output is active (NO switched on).

• Incorrect phase sequence → LED goes out and the output enters fault state.

Overvoltage protection (U>)

• If the voltage exceeds 500 V, the overvoltage indicator is activated.

• If this condition lasts longer than 2 s, the relay switches off the output.

• If the voltage falls 5 V below the U> threshold, the relay starts a delay countdown and then resumes operation.

Undervoltage protection (U<)

• If the voltage falls below 180 V, the undervoltage indicator is activated.

• If the condition does not end during the fault delay, the output is switched off.

• If the voltage rises 5 V above U<, the relay switches the output back on after a delay.

Status indicators

• 5 LEDs indicate:

  • Relay status (OUT)

  • High voltage (U>)

  • Low voltage (U<)

  • Phase sequence

  • Asymmetry / fault

Main features

• Wide operating voltage range: 180-500 VAC

• Fixed asymmetry: 11%

• Protection against:

  • Low voltage

  • High voltage

  • Asymmetry

  • Phase sequence error

  • Phase failure

• No neutral conductor required

• Fast response to fault conditions (approx. 1 s)

• LED display for all functions

• Suitable for motors, compressors, pumps, and other three-phase loads

Technical parameters