9. RADIATORS

a) Check the tightness of all the drain plugs and air release devices. It is advisable to loosen the air release to let out any air trapped inside and then to close properly.

b) The keys of the butterfly valves should be checked to ensure that the valves are in open position both at the top and at the bottom.

10. TRANSFORMER TANK

The following procedures should be done in the way they are mentioned below :

a) Open the air release device on the inspection cover and also on the tank cover to ensure that there is no air trapped inside the tank.

b) Gently open the nuts at the bottom of each HV bushings one by one and shake the stud gently until oil starts coming down. Then tighten the nuts properly. All bushings should be kept clean.

c) Again check the level of the oil in the conservator to ensure that the oil level has not gone down because of the trapped air being released from inside the tank. If necessary, fill oil again.

d) Check the IR value with a 2500 volt meggar in between -
              ( i) HV and earth;
              (ii) LV and earth and
              (iii) HV to LV.

Also note down the ambient temperature at which these readings have been taken. The meggar value should not be far below the specified values.

11. If facilities are available at site, oil sample can be taken out from the bottom drain valve to test the breakdown voltage of the transformer oil.

12. Before energising, it should be ensured that the transformer tank is properly earthed.

13. Do not handle the off-circuit tap switch when the transformer is energised. Also do not energise the transformer unless the switch handle is in locked position.

14. Do not leave secondary terminals of an unloaded CT open.