Phase protection relay - FKV-24F | TENSE

The FKV series phase protection relays 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 the reliable operation of devices with high demands on performance accuracy and protects them from thermal and mechanical damage.

Functions and operating principle

Stress asymmetry (11%)

• Monitors the difference between the phase voltages.

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

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

Examination of the phase sequence

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

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

High-voltage protection (U>)

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

• If this condition persists for longer than 2 seconds, the relay switches off the output.

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

Undervoltage protection (U<)

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

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

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

Status indicators

• 5 LEDs provide information about:

  • Relay status (OUT)

  • high voltage (U>)

  • low voltage (U<)

  • sequence of phases

  • Asymmetry / Error

Key features

• Wide operating voltage range: 180-500 VAC

• Fixed asymmetry: 11%

• Protection against:

  • Low voltage

  • High voltage

  • asymmetry

  • Errors in the phase sequence

  • Phase failure

• No neutral conductor required

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

• LED display for all functions

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

Technical parameters