CIRCUTOR OT2-60D - Manual (Page 13)

DIELECTRIC STRENGTH TESTER FOR ISOLATING OILS OT2-60D --------- Page 13
7.7. Turn on MAIN POWER
7.8. Depress the START pushbutton to start the test. Observe the test cell as the
output ramps up at the preset rate. The voltage will rise until the sample
breaks down. At breakdown, the unit will turn off, light the Fault LED and hold
the breakdown voltage reading.
7.9. After recording the breakdown voltage, depress the Reset/Fault pushbutton.
Allow the output control to return to zero.
7.10. The cycle previously desvribed will be carried out six times with the same
sample of oil. Between the cycles it will be necessary to wait to the
disappearance of the gas bubbles that have possibly been produced, either
waiting for 5 minutes, or selecting the stirring function.
7.11. Stopping the equipment , w hen the equipment is not used, turn off MAIN
POWER and the red Neon will be turned off.
7.12. Evaluating the results
Once we have finished all the cycles (six), we will write down the following
data to do the report:
- Sample identification
- The value of each one of the six disruptive voltages (kV)
- The average value of the six tests (kV)
- The type of electrodes we have used and the distance between them
- The frequency of the test voltage (50 Hz)
- The oil’s temperature
- If we have used the stirrer function or not
In order to determine if the state of the oil is correct or not, we will see if the
average value of the six tests is within the right operation range that indicates
the manufacturer of the oil. If the value is outside this range we will have to
adopt the opportune measures to diminish the degree of contamination of the
oil.
If you are not able to find another value, an habitually used criterion (but not
indicated by the standard) is to consider as good the oils that have an
average value of dielectric strenght higher than 80 kV/cm (remember that we
can obtain the dielectric strenght multiplying the disruptive voltage by 4, in the
case of following the IEC-156 standard).
***CAUTION***
POTENTIALLY LETHAL VOLTAGES MAY BE
PRESENT