On Load Tap Changer Services / Maintenance

1 MECHANISM To cover the variety of operating environments and circumstances, it is recommended that the exposed rubbing surface, displayed on the door, should be regularly lubricated after every 20,000 operations with the following lubricant.
Molysulf SG-3 The lubricant should be applied sparingly and an excess of it must be avoided as hardening of lubricant base can cause mal-operation.

2 SELECTOR SWITCH The Selector switch contacts should be examined after every 10,000 operations and replaced when the burning of the copper tungsten tips and blocks has progressed to the copper base.

3 OIL SAMPLING Oil samples should be taken and checked after every 5,000 operations or 6 months whichever is earlier for electrical breakdown. If the samples fail consistently below 30 KV for one minute in a standard test cell to IS. 335 the oil should be changed.
During an oil change, the selector switch should be cleaned down to remove adhering carbon. The tank should be cleaned out and filled with fresh oil having a test value of 40KV minimum to the level indicated on the sight gauge.

4 GENERAL CHECK Since every tapchange is carried out by a snap-action of moving parts, a general check of all nuts, bolts and other securing arrangements should be carried out after every 5,000 operations and all loose connections should be properly tightened up.

5 AFTER SALE SERVICE AND SPARES In the event of any difficulty experienced in operation or for spares, a reference should be made to OTC Type, Serial No, MKA 0.A. No as appearing on the rating plate.