Secondary Injection Test Solutions

Secondary injection tests are performed to verify the correct operation of the protection system with regard to everything that is connected to the secondary of the transformers. The secondary protection system may include protective relays, auxiliary relays, protection circuits, communications and control systems, metering devices, low-voltage devices, alarms, etc. Accordingly, the secondary injection test covers not only the testing of protective relays and their tripping settings, but also the checking of all associated circuits and devices involved in the proper performance of the secondary protection system.

The secondary injection test involves disconnection of the device and/or circuits from its normal CT/VT connection and it might include, among others, the following tests:


  • Test all kind of relays: the relay testing through secondary injection test may range from a simple check of some points of the relay characteristic to a complete verification of the protection scheme logic, even including the response to transient waveforms, harmonics, etc.
  • Test switches and connections
  • Check on-load wiring, trips, alarms and communications circuits, currents and voltage wiring, phase by phase.
  • Check phasing and polarity up to the relay terminals.
  • Test current, voltage and energy meters, transducers, sensors, motor overload units, etc.
  • Check low voltage circuit breakers (if solid-state trip units have accessible terminal blocks for secondary injection test, otherwise the primary current injection is preferred because verifies all the breaker, and not only the trip unit)


Related Products

Additional Information about secondary injection test solutions

Secondary injection test and primary injection test, the two sides of the coin

The secondary injection test may involve the testing of individual components, such as the important relay testing, but it is also essential to test the entire protection circuit, from beginning to end, which is preferably performed with primary injection testing, which also tests the CT/VT ratios, polarity and phasing. The primary injection test is always carried out after the secondary injection test, to ensure that problems are limited to the VT’s and CT’s involved, plus associated wiring, all other equipment in the protection scheme having been proven satisfactory from the secondary injection test. They are the two sides of the same coin, and one does not exclude the other.

If primary injection is not possible, it can be used the secondary injection test to find wiring and connection problems, or others that could be not detected if only relays are tested. At any case, the transformers must also be tested separately, since the secondary injection test does not inform about the correct ratios or proper outputs of the transformers or if they may become saturated. In this regard, the correct connections of the transformer secondaries are critical for proper relay operation, and phase angle of voltages and currents reaching the relays are affected by the transformer connections and all the intermediate wiring.

The secondary injection test simulates the current and voltage transformer secondaries, by injecting single-phase or three-phase currents and voltages into relays, devices o into the secondary circuits, performing all the corresponding checking and testing with normal and fault conditions.

The widest range of equipment for secondary injection test

The equipment for secondary injection test has been a main activity of SMC; our experience obtained during the past 30 years has enabled us to have a complete range of equipment with different philosophies for the various applications and customers, from the simplest and autonomous sets to fully automated, for quickly performing any type of secondary injection test.

  • QUASAR: The Quasar is the most advanced three-phase relay test set designed for the testing of secondary and IEC-61850 protections of any type with special focus on industrial and routine maintenance applications. Adds an unique capability in secondary injection test sets, as Mentor 12 does, MODULARITY, allowing users to acquire hardware extensions to expand testing capabilities as per your needs.
  • PTE-100-C Series: a world leader reference single-phase secondary injection test set. Since portability is important factor for secondary injection test, the PTE-100-C is the smallest and lightest by far. With outstanding 1000 VA power for up to 250 A, measurement and testing functions, large set of upgrading options and accessories, accurate and unbeatable fast testing, at competitive price. A must-have instrument for the wide diversity of secondary injection test works in any plant or substation.
  • PTE range: a wide series of digital, non-variac based, secondary injection test sets, single and 3-phase, with the required high accuracy and stability for all kind of secondary injection test, reversibility in all output channels (current/voltage), fault dynamic testing, and interconnection capability; portable units, with high power capability, and straightforward use.
  • MENTOR 12: Universal secondary injection test set, PC independent, with easy and intuitive touch-screen, modular concept up to 12 channels, advanced built-in test tools, independent amplifiers and lower maintenance. The MENTOR is perfectly suited for secondary injection test and relay testing, with a big sized screen that allows continuous graphic and visual monitoring of the test process, and the quickest and most complete manual control. The MENTOR integrates many useful test functions for secondary injection test, without the need of external PC, such as State Sequencer, Fault, Ramping, Pulse Ramps, Binary Search, COMTRADE playback, and on screen direct regulation of complex magnitudes (impedance, power, symmetrical components, homopolar voltage, etc).
  • PME-20-PH: the digital phase angle meter PME-20-PH is also suitable for checking phase deviation in any secondary installation, together with any of the secondary injection test sets. Quick phase angle measurement between two voltages, two currents or between current and voltage. Enhanced with frequency and power factor measurement.
  • PTE-30-CH: the portable digital timer PTE-30-CH is other SMC accessory which can be used for measuring trip time in relays and any pulse or time between two electrical events.
  • GOOSEMeter one: for IEC 61850 based networks, the GOOSEMeter One performs as a classic multimeter, for monitoring the correct GOOSE traffic and continuity of all the messages broadcast by the relays. With small size, no configuration and read-only design, it is the bridge between the code and power world for secondary testing.
  • LET-400-RD/RDC: any of the primary injection units of the LET range can also be used as source for secondary injection test, especially when higher current range is required. This unit, which provides up to 400 A in permanent range, and higher currents in short-term, includes also low current taps of 10 A and 50 A which made it also suitable for secondary injection test.
  • RAPTOR: similarly, and with higher power and stability, this multifunctional primary injection test system can also be used as source for secondary injection test purposes. In combination with the Raptor Polarity Tester accessory, can also be used for polarity testing of all the secondary wiring as a more straightforward and efficient method.

All equipment comes along with a full range of accessories for every need.  As usual with SMC test equipment, simplicity and ease-of-use are common to all secondary injection test solutions.

For more information, please check the related SMC products or contact us.

For additional Information about secondary injection test solutions, see the following contents

  • Injection Testing : EuroSMC offers the widest range of solutions for primary and secondary injection testing, adapted to every need and application.
  • Injection TesterDifferent primary and secondary injection tester options; initial selection keys to choose a suitable injection tester for every need.