Short Circuit Testing

To ensure reliability and safety of switchgear and circuit breakers, testing against applicable standards must be done in both R&D facilities for development purposes as well as at independent test houses for certification.

Because of its importance in the economy of a country, a set of strict regulations of how these apparatus should behave, and how they need to be tested, has been defined.

The “Short-Circuit Testing Liaison (STL)” has created an internationally accepted report called “Harmonization of Data Processing Methods for High Power Laboratories”.

This standard describes a set of rules on where and how to measure values in the digitized information.

The Challenge
In an electric power system, switchgear is the combination of electrical disconnect switches, fuses or circuit breakers used to control, protect, and isolate electrical equipment. Switchgears are used both to de-energize equipment to allow work to be done and to clear faults downstream.

During measurements in switchgear testing, the contacts will be opened (O), closed (C) and depending on the test type opened(O) again, this is called OC or OCO measurement.

The contacts movement is typically controlled by using electrical signals.

These signals initiate the movement of contacts in the mechanical switch for the circuit to be opened or to be closed.

For medium and low voltage switchgear measurements there is often no signal available for registering the exact position of the contacts, therefore the time between the open or close action and the measured moment of contact touch or separation will be determined in a no-load test first.

These variables then later can be used for the full load (short-circuit) tests.

To enable harmonized testing in both R&D as certification processes, required analysis routines are fixed in STL routines.

The HBM Solution

Transient Recorders 

Isolated Digitizers 

Test Sequencer 

Perception Software

The Perception Switchgear application allows easy setup of the testing routine by providing the user with an interface to identify his type of switchgear and type of test.

For the type of switchgear one has the choice for single or three phases, using travel and/or open-close signals and the applicable mains frequency required for some STL calculations.