10kv vacuum switch maintenance points - Database & Sql Blog Articles

Test - lowercase jpg

Kaixin micro test

Test probe P100-M3

Photocoupler

1. Vacuum bubble vacuum detection (1) Pull the two contacts of the switch tube to the rated opening distance, and gradually increase the power frequency voltage between the contacts. If it can withstand the rated power frequency withstand voltage for 1 min, it is qualified. The rated power frequency withstand voltage of the 10kv vacuum switch tube is 42kv. During the test, if there is a slight discharge sound in the vacuum bubble, it means that the vacuum has decreased. Even if the power frequency withstand voltage test passes, it cannot be put into operation as a qualified product, and should be replaced immediately.
(2) The test with the vacuum tester compares the test results with the values ​​measured during the factory test and the transfer test, and should not change significantly. The power frequency withstand voltage method can only find a vacuum interrupter with a severely reduced vacuum. When the vacuum chamber of the vacuum interrupter drops to 10-2 to 10-1 Pa, the power frequency withstand voltage can still pass. Therefore, in the newly revised DL/T596-1996 "Procedures for Preventive Tests for Electrical Equipment", the provisions on the vacuum switch have been added to the provisions of "Measurement of the vacuum degree of the vacuum interrupter after overhaul and minor repairs when conditions permit". . However, most of the vacuum detectors currently on the market need to be removed after the vacuum bubble is removed, which brings inconvenience to the maintenance and increases the workload of the mechanism adjustment. Some detectors do not need to remove the vacuum bubble, but the measurement accuracy is often not enough. This is to be solved by the relevant manufacturers, but the vacuum measured by the same instrument at different times is still comparable.
Since the vacuum bubble is subjected to the power frequency withstand voltage test, X-rays may occur. Therefore, some foreign vacuum bubble manufacturers have clearly indicated that they do not want to perform a withstand voltage test.
2. The opening distance of the vacuum circuit breaker and the adjustment of the over-travel distance refer to the distance between the two contacts of the vacuum switch tube when the circuit breaker is in the open state. The open distance has a great influence on the insulation performance. The size of the open distance is determined by the technical conditions of the vacuum switch tube. The test method is to select a point A on the moving conductive rod, and then select another point B on the vacuum switch tube fixing member, and determine the displacement difference of A relative to B when the switch is opened and closed. Commonly used adjustment methods are: (1) the same method of overtravel adjustment; (2) rotating the vacuum bubble at a certain angle to adjust the length of the moving conductive rod, and the vacuum bubbles of different installation methods can rotate at different angles. This method is more suitable for fine adjustment.
The overtravel refers to the displacement of the contact spring of the circuit breaker when the movable contact of the vacuum switch tube is moved from the open position to the contact of the dynamic and static contacts. The sum of the open distance and the over travel is the travel.
The effect of the overtravel: (1) to ensure that the contact maintains a certain contact pressure after a certain degree of wear; (2) provide buffering when the contact is closed, reduce bounce; (3) provide a certain initial speed when opening. The overtravel is adjusted by adjusting the length of the threaded guide rod (or joint bearing) of the threaded guide rod (or joint bearing) connected to the vacuum arcing chamber movable conductive rod to adjust the screwing or unscrewing thread length.
The measurement method of the overtravel is to measure the length of the contact spring in the branching and closing positions, and subtract the length of the closing when the opening is the overtravel of the contact.
The change in overtravel can reflect the amount of wear of the vacuum bubble contacts. The overtravel will affect the speed of the closing and closing, so the overtravel should be adjusted and recorded every time during the inspection. When the contact wear amount reaches a certain level, the vacuum bubble should be replaced in time. Different types of vacuum bubble contacts allow different levels of wear. When assembling the vacuum bubble, the nuts in several directions should be evenly tightened to avoid the force on one side of the switch tube.
3. The three-phase synchronous measurement of the vacuum switch The difference in the synchronism of the three-phase switching is generally not more than 2ms. The vacuum switching operation with poor synchronization is easy to generate high operating overvoltage. When the three-phase switching and closing synchronicity does not meet the requirements, the adjustment method is the same as the overtravel. Three-phase synchronism measurement can be used: (1) SC16 ray oscilloscope photographing method check; (2) vacuum switch comprehensive tester measurement; (3) millisecond meter measurement.
4. Measurement of contact contact resistance If the contact resistance increases and is not detected in time during operation, a vacuum bubble explosion may occur. The measurement method is the voltage drop method, that is, the conductive loop is passed through a direct current of 100 A, and then the voltage drop is measured.
5. Adjustment of the closing speed The opening and closing speed of the super-moving mechanism is mainly guaranteed by design and manufacture, and the user generally does not make adjustments. The opening and closing speed is adjusted by the closing and closing spring. The greater the spring force of the opening brake, the faster the opening speed and the slower the closing speed; the smaller the spring force of the opening, the slower the opening speed and the faster the closing speed. For the spring operating mechanism, the closing speed of the closing spring can be adjusted to change the closing speed; for the CD10 electromagnetic operating mechanism, the closing speed can be adjusted by adjusting the gap between the closing iron core rod and the top wheel. The opening and closing speed is generally in the range of 0.3 to 1.5 m/s. Different institutional requirements are different. After the actuator update or vacuum bubble update, the opening and closing speed is generally adjusted. According to our experience, there is usually no adjustment during normal overhaul. The opening and closing speed can be measured by a vacuum switch comprehensive tester.
6. The parts of the maintenance activities of the operating mechanism should be cleaned with lubricating oil to make the mechanism flexible, reduce wear and replace the damaged or worn parts in time; check all the fasteners to prevent loosening and close the switch. Do not bounce, open the door does not rebound, the action is light, not stuck, and compact. For the operating mechanism such as CT19, pay attention to the adjustment of the closing amount of the closing half shaft and the gusset plate, the opening half shaft and the gusset plate. The buckle amount is generally required to be between 1.8 and 2.5 mm. The amount of buckle is too large, the mechanism is rejected or rejected; the amount of buckle is too small, and the opening and closing operation of the mechanism is not reliable. For the operating mechanism using the flat five-link and half-axis trip, such as the CD17 electromagnetic mechanism, pay attention to the adjustment of the half shaft and the buckle buckle. The amount of the buckle will affect the minimum opening voltage, and even affect the correctness. Open. The buckle amount is generally 1.5~2.5mm
7. Withstand voltage of other auxiliary and control circuits: 2kV, 1min; insulation resistance value of the closing and closing coil > 10MΩ; minimum closing voltage: 85% of rated voltage; minimum opening voltage: 65% of rated voltage; DC resistance of the brake coil: no significant change compared to the past.
Adjust the angle of the auxiliary switch and the length of the connecting rod so that the auxiliary switch is accurately positioned in the opening and closing position.
The above data is for reference only, and the vacuum switch requirements produced by different manufacturers may be different.
8. Precautions (1) When applying the 1 minute power frequency voltage test between the fractures, the overvoltage absorption device such as the zinc oxide surge arrester should be removed from the system.
(2) Because the technical parameters of different types of vacuum foam are different, when the individual vacuum bubble test fails, try to use the same type of pipe to update, the general model is not easy to change. It is usually necessary to keep the vacuum switch clean and clean the dust on the insulators such as insulators and insulating rods in time.
(3) About maintenance standards. Because the characteristic parameters of different types of vacuum switches of different manufacturers are different, and even there are differences between the same batch of switches, the parameters provided by the factory should be used as maintenance standards during maintenance. In order to facilitate the comparison during maintenance and avoid the trouble of turning over the file, it is recommended that the manufacturer ask the manufacturer to print the relevant characteristic parameters of the vacuum switch such as stroke, overtravel, vacuum, etc. on the back of the vacuum switch or the back of the vacuum switch cabinet.