AC test transformer system generates a continuously adjustable AC test voltage. It is used for GIS high-voltage switchgears, cables and accessories, instrument transformers, power transformers, high-voltage circuit breakers, coupling capacitors, capacitive bushings, surge arresters, insulators, electrical porcelains and other electrical components in AC voltage withstand, partial discharge test and other scientific research.

When the high voltage test needs to be provided a resistive current; AC voltage test system composed by AC test transformer is the only available power; especially for the test that requires a stable voltage, even the test load changes (severe corona, wet & pollution tests) or inductive load. Therefore, the AC test transformer is common equipment equipped in all the testing stations and laboratories.

Characteristic

• Meet the low partial discharge measurement test requirements

• Modular structure, small space requirement

• Low impedance, widely use range

• Computer-controlled measuring system, easy to operate

• Perfect protection circuit to ensure the safety of personnel and equipment

• Surge and transient protection for sensitive electronic components

System Configuration

The system consists of:

Primary power supply side main components are switchgear and regulator; the regulator generates continuous adjustable voltage as the input power for AC test transformer.

The main component of the AC transformer test system is the test transformer; contains a single test transformer or several transformers in series.

For capacitive test object, at the low-voltage side (few at high-voltage side) equipped with compensating reactor.

The harmonic filter can be placed at the low voltage side.

Divider can be used for voltage measurement and partial discharge detection; HV filter (including the isolation impedance and coupling capacitors) can be used for lower partial discharge measurement.

A standard capacitor is needed when in capacitance or dielectric loss test.

The overvoltage quick protection device can effectively inhibit the overvoltage generated by the breakdown of the test object. The state-of-art computer-aided control system provides a friendly user interface.

Design of the test transformer

Insulated cylinder type

Insulated cylinder type: can be used in a single unit or cascaded, modular structure, easy to stack up. The insulated cylinder is made of epoxy reinforced glass fibers and filled with oil. Such a structure is suitable for indoor use, usually for short timeoperation (in accordance with IEC standard) at rated current. After running for the specified maximum time at certain current, the reactor needs to be cooled to ambient temperature, which means the usual pattern is intermittent operation.

Metal tank type

Metal tank type transformer capacity is larger than insulated cylinder type transformer, can be used for high voltage pollution tests, test line and continuous test required capacity. This design is most suitable for outdoor use and therefore recommended for use in areas with poor climatic conditions, especially in high humidity areas and tropical countries.

Metal tank type test transformer current is higher, can run continuously, suitable for rain and pollution tests. It can be equipped with oil or gas bushing, and directly connected to GIS.

All structures can be provided with air cushion chassis, easy to move in the high-voltage laboratory.

SF6 gas-insulated type

AC Test Transformer.pdf