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Repair and maintenance of generator
Date：
2022-12-28 11:06
1. Maintenance Method for Abnormal Increase of Generator Inlet Air Temperature
If the air outlet temperature and stator coil temperature of the generator do not exceed the specified value, the output of the generator may not be reduced, but the cause shall be found out and timely adjusted; When the specified value is exceeded, the generator output shall be reduced before inspection.
2. Maintenance method for abnormal temperature rise of generator coil and iron core
(1) If the specified value is exceeded, the load shall be reduced rapidly;
(2) Quickly check the temperature of cooling air and check whether the dust filter is blocked;
(3) Check whether the inlet and outlet valves of air cooler are closed.
3. Generator overload maintenance method
Short time overload operation is allowed for the generator. Overload parameters and time are determined as follows:
In case of overload, the load current shall be reduced to the allowable value within the specified time, and the temperature of each part of the generator shall be monitored not to exceed the standard.
4. Maintenance Method of Generator Three Phase Unbalanced Current Exceeding the Standard
When the three-phase unbalanced current of the generator exceeds the specified value, first check whether it is caused by the fault of the transformer circuit; otherwise, reduce the stator current so that it does not exceed the specified value; at the same time, closely monitor the temperature of each part of the generator; when the temperature rises abnormally and the unbalanced current increases, emergency disconnection and shutdown shall be performed.
If the unbalanced current does not exceed 10% of the rated value during grid connected operation, reduce the external active power and check whether the unbalanced current becomes smaller. If it is caused by the external network, the operation can be maintained or the external network can be disconnected.
5. Maintenance method for one of the indicator meters suddenly indicating malfunction or disappearance during generator operation
Refer to the indication of other meters to check whether it is caused by the damage of the instrument itself or its primary and secondary circuits. If the secondary circuit wire is damaged, the operation mode of the generator shall not be changed as much as possible; If the normal operation of the generator is affected, the load shall be reduced or the generator shall be shut down according to the actual situation.
6. Maintenance method for PT secondary voltage disappearance at generator terminal
(1) Change the automatic regulating excitation system to manual operation;
(2) Exit the generator compound voltage lockout overcurrent protection;
(3) Monitor and adjust the generator through other meters;
(4) Notify the turbine to monitor the generator;
(5) Check the PT circuit at the machine end. If the primary and secondary fuses are blown, replace them;
(6) After it is normal, the generator compound voltage lockout overcurrent protection is put into operation, and the excitation regulation mode is changed to automatic mode for operation.
This fault phenomenon:
(1) When the alarm bell rings, the "PT disconnection at generator end" alarm is given;
(2) The indication of generator active power, reactive power and voltmeter decreases or is zero.
7. Maintenance method for disappearance of secondary voltage of generator excitation PT
(1) Change the excitation regulation mode to manual operation;
(2) Check the excitation PT circuit and replace it if the primary and secondary fuses are blown;
(3) After returning to normal, change the excitation regulation mode to automatic mode for operation.
This fault phenomenon:
(1) The alarm bell rings and the "generator excitation PT disconnection" alarm is given;
(2) The generator terminal voltmeter of excitation regulating panel indicates zero.
8. Maintenance Method for Generator Unable to Raise Voltage
(1) Check whether the excitation regulation system is normal;
(2) Check whether the meter and PT primary and secondary circuits are normal;
(3) Measure whether the insulation resistance at high and low voltage sides of excitation transformer is qualified;
This fault phenomenon: the voltmeter has no indication or is very low when the generator is boosting.
9. Maintenance method of differential CT disconnection
Check whether the differential CT circuit is indeed disconnected through the current monitoring function of the protection device;
If the differential CT circuit is indeed disconnected, the differential protection shall be temporarily removed;
Check whether the terminal blocks of differential CT circuit are in good contact;
Check whether the differential CT body is abnormal;
After returning to normal, put differential protection into operation.
This fault phenomenon: the alarm bell rings and the "differential CT disconnection" alarm is given.
Regular maintenance:
Timely remove worn parts or upgrade components;
Check the lubricating oil level;
Battery inspection and cleaning connection;
Unit load test;
Verify the readings and indicators of the control panel;
Change the fuel and air filter.
