The Method and Necessity of Testing and Testing the Mechanical Characteristics of High Voltage Switches

Only by ensuring proper opening and closing speeds can the high-voltage switch give full play to its ability to break current, reduce the electrical wear of the contacts caused by the pre-breakdown during the closing process, and avoid contact burnout, fuel injection, and even explosion occurs. The decrease of the just-closing speed, if the closing is in a short-circuit fault, due to the effect of blocking the electrical power of the contact closing and closing, it will cause the contact to vibrate or put it in a stagnant state, which is also prone to explosion, especially when the automatic reclosing is not This is especially true in the case of success. On the contrary, if the speed is too high, the motion mechanism will be subjected to excessive mechanical stress, causing damage to individual components or shortening the service life. At the same time, due to strong mechanical shock and vibration, the contact bounce time will be lengthened. The situation is similar for vacuum and SF6 circuit breakers.

　　 The opening and closing of the high-voltage switch are severely different in different periods, which will cause the non-full-phase connection or cut-off of the line or transformer, which may cause overvoltage that may harm the insulation. Some aspects of the mechanical characteristics of high-voltage switches are represented by contact action time and movement speed as characteristic parameters. In the mechanical characteristic test, the main ones are just opening speed, just closing speed, opening speed, opening time, closing Opening time, closing-opening time, opening-closing time, opening and closing synchronicity, etc.

　　 1. Definition of time parameter

　　1, opening time

　　 refers to the time interval from the moment when the circuit breaker is opened (the moment when the opening command is received) to the moment when the contacts of all poles are separated. The opening time must be within the specified time range. If the opening time is too short, the DC component will be too large when the system is short-circuited, which may cause difficulty in opening; if the opening time is too long, the stability of the system will be affected.

　　2, closing time

　　 refers to the time interval from the moment when the closing circuit is energized to the moment when all pole contacts are in contact with the circuit breaker in the off position. It should have a short closing time, reduce the energy of the arc when closing, and prevent the arc from welding the contacts.

　　3, opening-closing time

　　 is the time interval from the moment when all the pole contacts are separated to the moment when the pole contacts first when the circuit breaker is auto-reclosing.

　　4, close-minute time

　　 is the time interval from the moment when the contacts of the first contact pole are contacted to the moment when all pole contacts are separated during the subsequent opening operation during the closing and opening process of unsuccessful reclosing or during the separate closing and opening operation of the circuit breaker.

　　5. Synchronization of opening and closing operations

It refers to the time difference between the three-phase breaking and contact instants of the circuit breaker during the opening and closing operations, and the time difference between the contact breaking and contact instants of the arc extinguishing units in the same phase. The former is called phase-to-phase synchronism, and the latter is called the same-phase fractures. Inter-synchronism.

　　 2. Definition of speed parameter

　　1, the contact speed

　　 refers to the movement speed at the moment when the moving contact is separated from the static contact during the opening of the switch. When the technical conditions are not specified, the national standard recommends to take the average speed within 0.01s just after the minute as the instantaneous speed of the just split point, and use the nominal overtravel calculation point as the just split point.

　　2, contact just closing speed

　　 refers to the instantaneous movement speed of the moving contact and the static contact during the closing process of the switch. When the technical conditions are not specified, the national standard generally recommends taking the average speed within 0.01s before just closing as the instantaneous speed of the just closing point, and the nominal overtravel calculation point as the just closing calculation point.

　　3, opening speed

　　 refers to the MAX of the average speed of the section during the opening of the switch, but the section length should be specified in accordance with the technical conditions, if not specified, it is calculated as 0.01s.

　　 The speed parameter of the circuit breaker is expressed by its opening and closing speed. Since the speed of the circuit breaker is different at each moment in the process of movement, the general concern is just opening, just closing speed and speed.

　　 Three, the method of measuring the time parameter of the circuit breaker

　　In the field test of the circuit breaker, the opening time, closing time, opening and closing synchronicity measurement should generally be carried out. For circuit breakers with reclosing operation, the opening-closing time and closing-opening time should also be measured.

　　 is measured by a high-voltage switch mechanical characteristic tester. It has the advantages of intelligence, multiple functions, accurate data, strong anti-interference, simple operation, small size, light weight, and beautiful appearance. It is suitable for various indoor, multi-oil switches, vacuum switches, and sulfur hexafluoride switches. Characteristic test. Main test items and functions: inherent opening and closing time of 12 fractures; reclosing time; different periods of opening and closing; just opening and closing speed; bounce time and amplitude; switch opening distance and switch overtravel ( Vacuum switch, preset switch stroke); average speed of opening and closing.