Electrical injection testing is used to validate the condition and electrical characteristics of various power system equipment, and is most widely used on the key protective devices (protection relays, circuit breakers, power transformers, instrument transformers, cabling, switchgear, etc.).

A circuit breaker, as well as its protective relays and devices, are subjected to primary and secondary injection tests. The injection testing’s ultimate objectives are to ensure that the safety system is safe and that it meets the parameters, criteria, configurations, and desired reliability. The electrical equipment is tested for tripping times, operational conduct, resistance, opening, closing, and insulation ability, among other things.

This involves a variety of testing methods that we can split into two categories for ease of selection: primary injection testing and secondary injection testing, which can include current and/or voltage injection testing. Electrical injection testing needs special high-quality testing equipment to ensure accuracy and performance.

Because of the grid’s diverse functional requirements, testing capabilities necessitate a new level of sophisticated test hardware and software to analyses the entire protection system’s (or individual protection component’s) operation in “real life” scenarios.

Rest assured that the comprehensive line of relay test equipment can handle any aspect of relay testing, no matter how complex.

Secondary injection tests

Prior to primary injection tests, secondary injection tests are often performed. The aim of secondary injection testing is to ensure that the protection scheme downstream of the protection relay is working properly (s). Why are these experiments performed before the main injection tests? This is because the risks to the LV side of the The primary (HV) side of the equipment has been disconnected to prevent any damage. These tests, as well as the equipment required to conduct them, are generally defined in the relay manufacturer’s manuals. Equipment under evaluation are reduced during initial testing. The scope of testing will be largely dictated by the client specification and relay technology used, and can range from a simple check of the relay characteristic at a single point to a complete verification of the scheme’s tripping characteristics, including the response to transient waveforms and harmonics, as well as relay bias checking.

Primary injection test 

This type of test examines the entire circuit, including the main and secondary windings of the current transformer, relay coils, trip and warning circuits, and all intervening wiring. There’s no need to mess with wiring, which eliminates the risk of new transformers shorting out, and there’s usually no need for switching in the current transformer or relay circuits. In high current/high voltage situations encountered at major electrical facilities such as substations, primary current injection testing is used. A large current (between 100 and 20,000 amps, depending on system configurations and test requirements) is pumped directly into the primary side of an electrical system, such as a circuit breaker. The test’s aim is to figure out how the system works. Primary injection checks are often performed after secondary injection tests to ensure that any issues are confined to the VTs and CTs involved, as well as any related wiring, and that any other equipment in the safety scheme has passed secondary injection tests.