Introduction:

YDSW series encapsulated SF6 gas insulation AC test transformers are especially designed for factory and field test of metal-clad switchgear (GIS), and substation equipments on-site testing. These transformers can be flanged directly to GIS, they make testing of such installations possible without feeding them through an air-SF6 bushing. If equipped with output bushing, they can also be used for AC voltage test of other HV apparatus.

In the factory, these transformers allow to test sub-assemblies and components directly in the manufacturing line, thus avoiding transportation to a central test facility, and extra handling. Particularly they are suited for on-site tests of GIS after assembly.

Compared to conventional oil insulation AC test systems, they are lighter and smaller, only about 1/6 height and 1/7 weight, also the merits of encapsulation remain effective during tests which is essential for PD testing.

Application:

AC test transformer systems are conventional AC high voltage test equipments, mainly designed for medium capacitance testing objects, particularly for tests requiring stable voltage even if the load changes under voltage (corona, wet & pollution tests).

Especially when the load is inductive (like inductive voltage transformers), tests need resistive current, AC test transformer systems are the only choice.

Configuration:

Principle:

Test transformer steps up the voltage coming from the regulating transformer. The controls act on the regulating transformer to adjust precisely the input voltage of the transformer and thus the test voltage.

If needed, a compensating reactor can be connected between the regulating and the test transformers and compensates the capacitive power required for the test object. This way, the regulating transformer and power line filter ratings can be kept small, and the requirements for the power supply are reduced.