Phase protective relay - FKV-24F | TENSE

Phase protective relays of the FKV series are designed to protect three-phase equipment, especially motors, from faults related to incorrect voltage values, asymmetry, phase failure, or incorrect phase sequence. FKV-24F operates in a wide range of 180-500 VAC and has a fixed asymmetry of 11 %.

Ensures reliable operation of equipment with high power supply accuracy requirements and protects it 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 about 1 s and opens NO/COM contacts.

• When the difference drops by 5 V, the relay considers the condition normal and reactivates the output after a delay.

Phase sequence check

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

• Incorrect phase sequence → LED turns off and output switches to fault state.

High voltage protection (U>)

• If the voltage exceeds 500 V, the high voltage indicator activates.

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

• When the voltage drops 5 V below the U> limit, the relay starts a delayed countdown and then continues operation.

Low voltage protection (U<)

• If the voltage drops below 180 V, the low voltage indicator activates.

• If the condition does not end within the fault delay time, the output switches off.

• When the voltage rises 5 V above U<, the relay reactivates the output after a delay.

Status indications

• 5 LED diodes 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 protection

  • High voltage

  • asymmetry

  • Phase sequence errors

  • phase failure

• No neutral conductor required

• fast fault response (approximately 1 s)

• LED indication of all functions

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

Technical parameters