Figure 3-2. Connection for testing transformers.

TM 11-6625-298-14

Figure 3-2. Connection for testing transformers.

b. Measure the high- and low-voltage windings

considerably lower. Extremely low readings in-

dicate the presence of moisture in the oil and

separately. Connect a test lead from the LINE

indicate that the oil should be changed.

terminal of the ohmmeter, first to the low-voltage

windings and then to the high-voltage windings.

3-9. Insulation Test of Capacitors

c. Measure between windings by connecting the

WARNING

GROUND lead from the ohmmeter to one winding

Discharge the capacitor after an insulation

of the transformer, and another test lead from the

resistance test has been made, or

LINE terminal of the ohmmeter to the other

disconnect the leads one at a time. Short

winding.

out the capacitor. Contact with a fully

d. Turn the hand generator crank at operating

charged capacitor can cause a dangerous

speed. Indications for all measurements should be

shock.

100 megohms or more on air core transformer.

Indications on oil-filled transformer will be