Primary Injection Testing

Primary Injection Testing is carried out to verify the protection schemes operates within the manufacturers specifications throughout the complete circuit.

Unlike Secondary Injection Testing this proves the whole circuit rather than individual protection components. This is normally a high current test to prove that the system can withstand the stress associated with the fault currents of the equipment.

The injected currents are in the range of 2-10 times the breaker current rating.

Primary Injection Testing is most commonly used to prove:

  • Circuit Breaker trip unit
  • Correct CT operation
  • Correct CT ratio and polarity
  • Primary and secondary circuit wiring
  • Auxiliary trip circuits (under voltage, shunt trips) and remote operation

In house equipment includes OMICRON CPC100 systems with capabilities of up to 2kA. The full test kit also contains various auxiliary equipment like AC/DC power supplies for checking various coil types, an assortment of adapters to couple the test set with the breaker and various cable sizes to accommodate the testing of a wide range of breakers


  • Ground resistance meter
  • Micro ohmmeter 400 ADC
  • Turns ratio meter for transformers, CTs and VTs
  • Tester for Rogowski coils and other unconventional CTs / VTs (IEC 61850)
  • High-current injection transformer
  • Winding resistance meter
  • Power meter (P, Q, S)
  • Protection relay tester (one phase V, I, f)
  • Excitation curve tester • Phase angle meter
  • Multimeter (V, I, R, Z, …)
  • Step up transformer 2 000 V
  • Line impedance and cable measurement
  • Complex impedance meter (burdens, cables, lines and transformers)
  • On load tap changer test equipment
  • Vector group verification system for power transformers
  • Power / dissipation factor measurement set
  • Polarity checker