Action behavior a. Open. The opening command is received at the closing position, the opening coil is actuated, the reversing valve is switched to the opening position, and the high pressure oil of the differential piston is connected to the low pressure oil tank through the reversing valve, and the piston is fast under the action of the upper end of the differential piston. The downward movement is opened, and the auxiliary switch is switched to cut off the opening circuit to prepare for the next closing.
b. Closing. When the switch is closed, the front stage valve is energized, and the high pressure oil is guided to the lower part of the piston through the valve body. Although the piston is high-pressure oil on both sides, due to the different areas on both sides of the piston, the pressure difference generated pushes the piston to move, and the piston is connected to the tie rod of the circuit breaker for closing.
Hazard statistics from frequent pressures indicate that 65% of high-voltage circuit breaker failures are caused by abnormal operating mechanisms. For hydraulic operating mechanisms, frequent pressure suppression is one of the common faults. In addition to the low pressure of the mechanism to block the switch, the HMB-4/8 type switch spring operating mechanism is mainly caused by the indirect impact on the mechanism.
a. The energy storage module and the piston in the working cylinder are frequently compressed, so that the sealing parts such as the sealing ring are obviously increased in wear, and even the piston is worn, which may cause the internal leakage or the internal leakage of the mechanism to be intensified, and the fault is enlarged (the mechanism pressure is low closed). b. Frequent pressure is caused by impurities in the oil, which increases the wear between the moving parts, and the chance of scratching the module, the inner wall of the working cylinder and the piston increases.
In general, for the HMB-4/8 hydraulic operating mechanism, it is normal to start 1 to 3 times within the mechanism 24h due to the presence of a weak seal such as a seal ring. In the case of no operation or low operation of the circuit breaker, if the oil pump starts 10 times a day or more than 300 times per month, it can be regarded as frequent pressure failure (the field is judged by alarm or counter). The HMB-4/8 frequent pressure criterion is that the motor starts more than 20 times within 24 hours. At this time, the mechanism needs to be inspected and processed.
Frequent pressure reasons The pump start principle is the hydraulic mechanism stroke, and the pump start monitoring circuit is as shown. F1 is the reed spring control pump stroke switch contact. When the mechanism pressure is reduced, the spring stroke position is reduced to 8115mm, the contact point is closed, the oil pump motor circuit is turned on, and the high pressure oil output from the oil pump enters the upper end of the three energy storage pistons at the same time to promote the storage. Capable piston down to Table 1 Hydraulic mechanism stroke Spring hydraulic mechanism stroke position / mm (allowable error ± 1mm) fulcrum limit comminuted limit merging limit limit priming pump maximum pump HMB-84010511077158115831584152 pump start monitoring circuit indication (only The stack spring travel switch section) moves the stack spring to store energy. After the energy storage is in place, the F1 contact opens, the spring travel switch cuts off the oil pump motor, the oil pump stops, and the pressing process ends. When the operation or the pressure is reduced to the start pump value, the spring travel switch is turned on and the oil pump motor is replenished to the pump stop position. F2 is the closing and closing contact point. Only when the stroke position is reduced to below 5110mm, the contact is closed; the K1 contact is the auxiliary contact of the switch and the joint is closed when the switch is at the joint.
a. Inspect the site for leaking oil. Check whether the oil level of the mechanism is normal, whether there is leakage oil on the outer surface of the mechanism, and whether the spring is broken or broken. If there is oil leakage on the surface of the mechanism, check the location of the leaking oil and replace the corresponding module.
b. Frequent suppression of faults only in the quintile. When the switch is in position, the piston on both sides of the working cylinder is high-pressure oil. When the position is in position, the working cylinder is high-pressure oil on one side and low-pressure oil on the other side. For the frequent pressure failure in the switch position, the switch can be closed. If the energy storage is completely normal, it can be preliminarily judged that there is leakage in the high and low pressure oil passages on both sides of the piston in the working cylinder. Since the site does not have the working cylinder maintenance conditions, the organization needs to be returned to the factory for processing.
c. Eliminate the cause of impurities in the oil and the cause of the secondary circuit. On-site closing and energy storage operation several times, for the frequent pressure failure of the switch in the joint position, the spring can not completely store energy after several operations (to protect the motor, the motor running continuous upper limit time is 2min), disconnect If the motor is discharged to 0 pressure after the power supply, the cause of impurities in the oil and the cause of the secondary circuit can be excluded. At the same time, the opening and closing operation can check whether the position of the solenoid valve of the opening and closing coil is normal and the action is flexible.
Compared with traditional hydraulic operating mechanisms such as CY type, HMB-4/8 hydraulic operating mechanism has less experience in domestic operation and maintenance. However, due to its compact structure and no external piping, it has been widely used. Frequent suppression is a typical failure. If the analysis of structural characteristics is adopted and a more standardized analysis process is adopted, the power outage time can be shortened.
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