Theory

The two unit portable testing set is designed for the periodical testing of samples of insulating oils drawn from plant on site and for checking the dielectric strength of new samples of oil.

The equipment is designed to operate from 200/250V, 50Hz, Single phase AC supply. Test gap voltage up to 50kV, it consists of two units, one is containing the testing transformer and other is control and metering equipment. These equipments are kept in a metal box to provide full protection to the apparatus during transport and storage.

The gap is adjusted between electrodes in accordance with British Standard Specification (BSS) no. 148.

Procedural Steps

1. Place the High Voltage transformer unit about 7 feet away from the control unit.

2. The control unit is connected to supply voltage taking care that the earth connections are effective.

3. The multiple point control switch is set at its lowest tapping.

4. The push button on control unit is pressed firmly for at least 5 seconds. Note that no breakdown occurs, in which case button should be released at once without delay. Breakdown is indicated by a continuous discharge across the gap, bubbling of oil in the cell and meter indicating a sudden voltage drop.

5. Experiment 4 - Equipments Required

Fig.1: Portable oil testing set

Fig.2: HV transformer

Fig.3: Gap setting gauge