UNIT-AP Arc Protection Device

The UNIT-AP device is designed for instantaneous arc fault protection. Can be used in low or medium voltage switchgears with the alternating or direct current. In a short circuit accompanied by an opened arc, the fiber optic sensor (FOS) can quickly localize the fault. Minimizes damage of electrical equipment, improves the reliability of power supply and increases the safety of staff.


  • High-speed arc detection via fiber optic sensors.
  • Extremely short operating time (≤1 ms).
  • Up to 4 loop sensors (max length 10 m of each) or 2 radial sensors (max length 25 m) resistant to the EMC.
  • influences and sensitive to the radiation pulses in the visible wavelength range.
  • 6 output relays (2xHigh-speed solid state relays, 3xSignalization relays, IRF).
  • Up to 2 binary inputs (OCP start signal monitoring from an external relay).
  • 7xLEDs, «Reset» button on the front panel.
  • CBFP.
  • Configurable software logic.
  • Communication port 1xRS-485 (Modbus RTU).
  • Free software for configuring and monitoring.
  • Time synchronization.

Basic configuration

Number of Ports (Interface, Protocol) 1 (RS-485-2W, Modbus RTU)
Mounting DIN rail
Dimensions (mm) 124х135х68

Technical specifications

Input Voltage 110, 220 VAC / VDC
Consumption (Watt) max 4
Weight 0,6
Overall operating time (from arc detection to trip output relay), ms < 1
Number of fiber optic sensors, max    
2xHigh-speed solid state relays 

4xSignalization relays  
Binary inputs    
up to 2 (option)    
Self-supervision time interval (sensors)    
15 sec    
Overall start time, s      
< 0,3    
Time of backup power (after power down), s

Price request