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Hardware Features of Universal Relay Test Kit K68i:

  • All-in-one design relay tester with 6.4 inches LCD display.

  • Four  independent AC voltage sources of 0- 300V @ 110VA each.

  • Three  independent current sources  of 0- 35A @ 450 VA each .

  • One independent Auxiliary DC Source of 0 ~ 300V/0.6A .

  • High accuracy analog outputs of <0.15%rd + 0.05%rg,Guar.

  • Projector compatible port for training & study purpose .

  • Rugged Design with super long life rotary encoder + Functional keyboard.

Software Features of Universal Relay Test Kit K68i:

  • Able to test most of Relays by manual or automation: Voltage relays, Current relays, Frequency relays, Power relays, Impedance relays, Harmonic relays, Distance relays etc .

  • With self-housing & grounding-detecting function

Theory of Relay   

Protective relays are used extensively across the power system to remove any element from service that suffers a short circuit, starts to operate abnormally or poses a risk to the operation of the system.


The relaying equipment is aided in this task by instrument transformers that sense power conditions and circuit breakers that are capable of disconnecting the faulty element when called upon by the relaying equipment.

Due to their critical role in the power system, protective relays should be acceptance tested prior to being placed in service and periodically thereafter to ensure reliable performance. In a normal industrial application, periodic testing should be done at least every 2 years in accordance with IEC/IS Standard . 

Relay Testing Kit – Theory

Relay is a switching device, which issues a trip command to the Circuit Breaker during abnormal fault conditions. A Relay receives the input signals from CT’s/ PT’s and its program calculates the fault conditions as per application. It issues a trip command to the Circuit Breaker on sensing a faulty condition.  

Step 1:

Relay Testing Kit injects fault in form of I & V on respective CT & PT points of Relay under test . The Timer of Relay Testing Kit starts by initiating  fault injection.

Step 2:

Relay senses the fault & issues the trip command, its trip timing must depend on the time characteristics of relay settings.

Step 3:

Relay Testing Kit receives the trip command from Relay & Stops the timer.

Step 4:

The measured tripping characteristics are compared with respect to expected tripping as per settings by Engineer.


Electromechanical Relay Testing


The secondary of current transformer is connected to the current coil of relay. The secondary of voltage transformer is connected to the voltage coil of the relay. Whenever any fault occurs in the feeder circuit, proportionate secondary current of the CT will flow through the current coil of the relay due to which mmf of that coil increases. This increased mmf is sufficient to mechanically close the normally open contact of the relay. This relay contact actually closes and completes the DC trip coil circuit and hence the trip coil is energized. The mmf of the trip coil initiates the mechanical movement of the tripping mechanism of the circuit breaker and ultimately the circuit breaker is tripped to isolate the fault.

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