(1) At or near connections to the impulse generator, including earth or earthed
conductors in the vicinity.
(2) At any other terminal of the cable or connected equipment.
(3) At or near the fault where earth voltage gradients may exist. The fault location
is unknown, so caution must be exercised all along the buried cable run.
c) Any persons not directly associated with the work must be kept away from the
danger area by suitable barriers, barricades, or warnings.
d) After the faulty section of cable has been isolated, the maintenance electrician
should use a cable fault locator to pinpoint the actual location of the fault.
Portable Oil Tester
a) The portable oil tester, Figure 12, is used to test the oil in large transformers.
b) The oil is the key to the length of life of a liquid-filled transformer. The oil
provides the electrical insulation and conducts heat away from the windings.
c) The oil should be sampled and tested as indicated in the section on regulators.
Typical Portable Oil Tester
a) To test the oil in a large transformer, separate samples are taken from both the top
and bottom of the transformer and poured into the oil tester separately so that the oil covers two
electrodes separated by a small gap. Oil from circuit breakers is tested in a similar manner.