Fault analysis and maintenance of the hottest Cy3

2022-08-15
  • Detail

Cy3 type hydraulic operating mechanism 2.3 batch experiment can realize fault analysis and maintenance of hierarchical display of curves

Cy3 type hydraulic operating mechanism is used for oil less circuit breakers in some 110220 kV substations of our company. Due to the long operation time of circuit breakers, most of which are more than 10 years, some parts of their hydraulic operating mechanism are aging, resulting in a lot of fault phenomena in operation, some of which are relatively prominent, Seriously affect the reliability index of the company

1 the oil pump starts frequently

1.1 fault phenomenon

under the condition of no operation of the hydraulic mechanism of the circuit breaker, the relevant regulations stipulate that the number of starts of the oil pump motor per day is generally not more than 25 times for the environmental protection bag produced by PCC high-energy masterbatch. Some substations of our company have experienced frequent failures of Cy3 hydraulic mechanism oil pump motor startup, up to 90 times/day

1.2 cause analysis

(1) there is oil leakage at the pipe joint

(2) the steel balls of the primary and secondary valves are not tightly sealed, and oil leaks from the oil drain hole

(3) if there is no problem in appearance inspection, the high-pressure check valve at the oil pump outlet may be loose; The data measured with this condition is helpful to identify the problems between the actual experiment and the system

(4) if the mechanism is in the off state, and the oil pump is also started frequently, it indicates that the steel ball of the closed secondary valve is not tightly sealed. From the outside, the oil seeps out from the oil drain hole of the closed secondary valve (that is, the oil seeps from the three holes)

(5) the oil drain valve is not tightly closed

(6) the sealing ring of the piston of the working cylinder is not well sealed

(7) there are impurities in the hydraulic oil, which are stuck in each sealing ring, resulting in poor sealing

1.3 treatment method

(1) replace all sealing rings

(2) check the piston connecting rod of the working cylinder. If there are longitudinal scratches, replace them according to the situation or gently polish them with fine sandpaper until they are smooth

(3) filter and replace the hydraulic oil

(4) replace the damaged parts

1.4 maintenance precautions

(1) when replacing the sealing ring of the working cylinder, it should be noted that the piston connecting rod does not touch any hard and sharp objects

(2) when replacing the sealing ring, flush it with hydraulic oil

(3) the hydraulic oil should be pure and thoroughly filtered when changing and filling oil

(4) workers should ensure that their hands are clean and free of impurities during work

2 the hydraulic system cannot build pressure normally

2.1 fault phenomenon

when the circuit breaker is closed again after the opening operation, the oil pump motor is pressurized for a long time, and the pressure cannot rise to the pump stop pressure

2.2 cause analysis

(1) each high-pressure seal ring in the oil pump is damaged or the ball valve is poorly sealed. If you touch the oil pump with your hand, you may get hot

(2) the oil filter is blocked by dirt, which affects the passage of oil

(3) there is air on the low pressure side of the oil pump

(4) the high-pressure oil drain valve is not reset, and the high-pressure oil is directly put into the oil tank

(5) the plunger clearance is too large, and the steel ball of the oil suction valve does not reset

(6) the primary and secondary valves are not tightly sealed, and there may be valve port wear or ball holder overturning

(7) after the overhaul of the oil pump, the plunger was not injected with an appropriate amount of hydraulic oil during assembly, or the plunger rod and bead plug seat were not wiped clean

2.3 treatment method

(1) replace all sealing rings

(2) clean the oil filter and oil pump

(3) repeatedly pressurize and exhaust the air in the oil pump

(4) check whether the high-pressure oil drain valve is reset, and replace it if it is damaged

(5) if the pressure relief part cannot be checked, the opening and closing valves at all levels should be reassembled

2.4 maintenance precautions

(1) pay attention to flushing each removed pipeline with hydraulic oil

(2) the hydraulic oil shall be stored in a ventilated and dry place to ensure good sealing and prevent the entry of moisture and impurities

(3) after the maintenance, the pressure should be pressed many times to exhaust the air in the pipeline

(4) ensure accuracy and reliability during installation

3 abnormal pressure increase or decrease of hydraulic operating mechanism

3.1 fault phenomenon

abnormal pressure occurs in the circuit breaker during operation, which leads to high-voltage locking opening and closing or pressure reduction to zero in serious cases

3.2 cause analysis

3.2.1 abnormal pressure rise

(1) microswitch 1ylj (1ck) fails, so that when the piston rod of the pressure storage tank exceeds the 1ylj position, the motor power supply cannot be cut off, and continue to pressurize

(2) the sealing ring of the pressure storage tank is damaged or the tank wall is worn, and the hydraulic oil enters the air storage tank

(3) pressure gauge failure or error

(4) the intermediate relay "sticks", and its contact cannot be disconnected

(5) the contactor is stuck and the motor is always running

3.2.2 abnormal pressure reduction

(1) pressure gauge failure or error

(2) there are a lot of oil leaks in the mechanism box, and the valve body is "padded" by dirt in the oil or damaged by rubber rings (at this time, the oil pump will operate continuously)

(3) if the connecting rod of the pressure storage tank is in the normal stop position and the pressure continues to decrease, there may be leakage at the weld of the pressure tank

(4) the one-way check valve on the nitrogen cylinder is not tightly sealed, air leakage or the two sealing rings at the head of the piston rod of the pressure storage tank are damaged, causing nitrogen to enter the oil

3.3 treatment method

(1) check the microswitch, pressure gauge, intermediate relay and contactor. If they are damaged, replace them and polish the microswitch contacts

(2) check the pressure storage tank, and replace it if the tank is damaged

(3) replace all sealing rings

3.4 preventive measures

(1) during planned outage maintenance, attention should be paid to checking the conditions of all parts of the mechanism, replacing damaged parts in time, and minor maintenance should be carried out in strict accordance with the maintenance process standards

(2) after maintenance, pay attention to check whether each contact of the microswitch corresponds to the corresponding pressure value

(3) strengthen the comprehensive maintenance work, and comprehensively inspect the mechanism when dealing with defects to avoid repeated maintenance

(4) prepare various spare parts

4 Conclusion

the most common fault of Cy3 hydraulic operating mechanism is that the oil pump motor starts frequently. According to years of observation and statistics, the problem of frequent starting of oil pump motor has a certain regularity, that is, the problem begins to be exposed in summer, and tends to be normal in autumn and winter. This is caused by the fact that we found that the high temperature of wood flour in the hydraulic oil when heating leads to the decline of the performance of the sealing ring, Therefore, we must pay attention to ensure the good ventilation of the mechanism box and strengthen the inspection of the equipment

in recent years, the company has used the planned power outage to carry out a large number of targeted overhaul work of Cy3 hydraulic operating mechanism, filter hydraulic oil, replace sealing rings, and replace damaged parts, so as to prevent accidents, so as to basically eliminate various faults of Cy3 hydraulic operating mechanism and improve the power supply reliability of the equipment

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