Testing facilities are fully equipped to carryout all pre-scribed routine tests on the Transformers Manufactured. We encourage our clients in the private sector to witness final testing of their equipment and keep them intimated on the testing dates. Arrangement s for any special test s at the discretion of the client are also made after agree-ment on the costs involved, if not mentioned in the pur-chaser/ work order. Public sector clients however follow their departmental procedures formulated for this purpose to which we fully comply.

SHORT CIRCUIT TEST

The test is conducted on the high-voltage (HV) side of the transformer where the low-voltage (LV) side or the secondary is short circuited. The supply voltage required to cir-culate rated current through the transformer is usually very small and is of the order of a few percent of the nominal voltage and this 5% voltage is applied across primary. The core losses are very small be-cause applied voltage is only a few percentage of the nominal voltage and hence can be ne-glected. Thus the wattmeter reading meas-ures only the full load copper loss. The test performs at H.V S.C , Rawat, Laboratory , Islamabad.

IMPULSE VOLTAGE TEST

Lighting is a common phenomenon in trans-mission lines because of their tall height. This lightning stroke on the line conductor causes impulse voltage. The terminal equipment of transmission line such as power transformer then experiences this lightning impulse volt-ages. Again during all kind of online switching operation in the system, there will be switch-ing impulses occur in the network. The magni-tude of the switching impulses may be about 3.5 times the system voltage. Insulation is one of the most important con-stituents of a transformer. Any weakness in the insulation may cause failure of trans-former. To ensure the effectiveness of the insulation system of a transformer, it must confirms the dielectric test. But the power frequency withstand test alone can not be adequate to demonstrate the dielectric strength of a transformer. That is why impulse test of transformer performed on it. Both lightning impulse test and switching impulse test are included in this category of testing. The Test performs at H.V & S.C Lab, Rawat, Islamabad.

Testing Department