Operation and maintenance of on load tap changer o

Operation and maintenance of transformer on load tap changers

in recent years, more and more on load voltage regulating tap changers are used in 110kV and below transformers, most of which are domestic. Most of the tap changers are of resistance type, and the overall structure can be divided into three parts: control part, transmission part and switch part. On load tap changer plays an important role in improving the voltage qualification rate of power supply system. At present, the voltage regulation means of county-level power supply relying on large power supply mainly rely on on load voltage regulation transformer. This has pushed the operation and maintenance of on load voltage regulating transformer and tap changer to an important position

1 maintenance contents and requirements

(1) before the on load tap changer is put into operation, the conservator should be checked, its oil level should be normal, there should be no oil leakage, and the control box should be moisture-proof. For manual operation for one cycle (i.e. one cycle of rise and fall), the gear indicator and counter should act correctly, the locking of limit position should be reliable, and the interlocking of manual and electric control should also be reliable

(2) gas protection of on load tap changer, heavy gas input tripping, light gas sending signal. This is the same as the gas protection requirements of the transformer body. We usually call the gas relay of the body "big gas", and the gas relay of the on load tap changer "small gas". The gas relay shall be installed at a position convenient for safe venting during operation. After the gas relay of the newly put into operation on load tap changer is installed, the operator should vent gas in time when necessary (there is gas in the cylinder)

(3) the electric control of the on load tap changer shall be correct, the power supply shall be reliable, and the connection terminals shall be in good contact. The drive motor rotates normally and turns correctly, and the rated current of its fuse is configured as 2 ~ 2.5 times of the rated current of the motor

(4) the power control circuit of the on load tap changer, the electric operation button installed on the control panel and the button installed on the on load tap changer control box on the transformer body should be intact, the power indicator and gear indicator should be intact, and the electrical locking at the limit position should be reliable

(5) the electric control circuit of the on load tap changer shall be equipped with a current locking device, whose setting value is 1.2 times the rated current of the main transformer, and the return coefficient of the current relay is greater than or equal to 0.9. When automatic voltage regulation is adopted, there must be an action counter on the main transformer control panel, and the secondary disconnection locking of the voltage transformer of the automatic voltage regulator should be correct and reliable

(6) when the on load tap changer is newly installed or overhauled, the remote electric operation button and the manual equipment on the transformer site should be used in the construction control room of the RO Ro Wharf in the main acceleration new harbor area when the transformer is in no-load operation. The indication of gear and voltage is correct, and the electrical locking of the limit position is reliable. Then it can be adjusted to the tap gear required by the dispatching to operate with load, and the monitoring should be strengthened

(7) the attendant automatically adjusts the voltage according to the voltage curve and voltage signal issued by the dispatcher. Each operation shall carefully check the change of tap action voltage and current (once for each gear adjustment), and make records

(8) when two on load voltage regulating transformers operate in parallel, tap changer operation is allowed under 85% of the rated load current of the transformer. However, two tap changing operations cannot be carried out continuously on a single transformer. It is necessary to conduct a tap change operation of another transformer after one tap change operation of one transformer is completed. Before an on load voltage regulating transformer and an off load voltage regulating transformer operate in parallel, the tap changer of the on load voltage regulating transformer must be adjusted to the same or similar gear as the off load voltage regulating tap changer, even if the secondary voltage of the two main transformers is the same or similar. When the on load voltage regulating transformer and the off load voltage regulating transformer operate in parallel, it is strictly forbidden to adjust the tap changer

(9) ensure that the equipment can be used normally. When the on load tap changer control is carried out by the personnel on duty, it should be carried out according to the patrol inspection requirements. Before and after the operation, it should be planned and required to establish a plastic construction plant in a certain place in the American corn belt. Pay attention to and observe whether there are bubbles in the gas relay