Experiment - 4

OBJECTIVE


To measure the dielectric strength of transformer oil.


EQUIPMENTS REQUIRED


  1. Portable oil testing set-220/250 V
  2. HV transformer-50 kV/250 V
  3. Gap setting gauges -0.15711 width

CONNECTION DIAGRAM

Fig 4.1: Portable oil testing set (50 kV)


PROCEDURAL STEPS

  1. Place the High Voltage transformer unit about 7 away from the central unit.
  2. The central 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 to occurs, in which case button should be released at once without delay. Break down is indicated by a continuous discharge across the gap, bubbling of oil in the cell and meter indicating a sudden voltage drop.