Phase Protection Relay - FKV-24F | TENSE

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

It ensures reliable operation of equipment with high power accuracy requirements and protects it from thermal and mechanical damage.

Functions and Operating Principle

Voltage Asymmetry (11%)

• Monitors the difference in phase voltages.

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

• When the difference drops to 5 V, the relay evaluates the condition as normal and resumes output after a delay period.

Phase Sequence Check

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

• Incorrect phase sequence → LED turns off and the output goes into a fault state.

Overvoltage Protection (U>)

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

• If the condition persists for more than 2 seconds, the relay deactivates the output.

• When the voltage drops 5 V below the U> limit, the relay starts counting the delayed time and resumes operation.

Undervoltage Protection (U<)

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

• If the condition does not end within the fault delay time, the output is deactivated.

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

Status Indications

• This is indicated by 5 LEDs:

  • relay status (OUT)

  • overvoltage (U>)

  • undervoltage (U<)

  • phase sequence

  • asymmetry / fault

Key Features

• Wide operating voltage range: 180-500 VAC

• Fixed asymmetry: 11%

• Protection against:

  • Undervoltage

  • Overvoltage

  • Asymmetry

  • Phase sequence error

  • Phase failure

• No neutral conductor required

• Fast response to faults (approx. 1 s)

• LED indication for all functions

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

Technical Parameters