Phase protection relays - FKV-24F | TENSE

The FKV series phase protection relays are designed to protect three-phase equipment, especially motors, against damage due to incorrect voltage values, asymmetry, phase failures, or incorrect phase sequence. The FKV-24F operates in a wide 180-500 VAC range and has a fixed asymmetry of 11%.

It ensures reliable operation of equipment with high demands on power precision and protects them from thermal and mechanical damage.

Features and operating principle

Voltage asymmetry (11%)

• Monitors the difference in phase voltages.

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

• If the difference drops by 5 V, the relay evaluates the state as normal and resumes output operation after a delay period.

Phase sequence check

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

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

High voltage protection (U>)

• If the voltage exceeds 500 V, a high voltage indication is activated.

• If the condition persists for more than 2 s, the relay disconnects the output.

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

Low voltage protection (U<)

• If the voltage drops below 180 V, a low voltage indication is activated.

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

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

Status indications

• 5 LEDs provide information about:

  • relay status (OUT)

  • high voltage (U>)

  • low voltage (U<)

  • phase sequence

  • asymmetry / error

Key functions

• Wide operating voltage range: 180-500 VAC

• Fixed asymmetry: 11%

• Protection against:

  • Undervoltage

  • Overvoltage

  • asymmetry

  • phase sequence errors

  • phase failures

• No neutral wire required

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

• LED indication of all functions

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

Technical parameters