"locking" is a measure to prevent electrical misoperation. Our electrical operators are most afraid of misoperation, including:
1. Pull and close the disconnector with load;
2. Switch on with grounding wire (grounding knife);
3. Personnel mistakenly enter the electrified interval;
4. Misdividing and closing circuit breakers by mistake;
5, live ground wire (grounding knife).
and non-simultaneous juxtaposition.
Among them, locking includes: mechanical locking is a locking mode in which the mechanical structure of the operating mechanism of switchgear restricts each other, so as to achieve mutual interlocking.
electromagnetic locking is to use the auxiliary contacts of circuit breakers, disconnectors, circuit breaker doors, etc. to turn on or off the power supply of electromagnetic locks such as disconnectors and switch cabinet doors that need to be locked, so that their operating mechanisms cannot act, thus realizing the mutual locking between switching devices. The locking device is simple in principle and convenient to realize, and locking can be realized between different switchgear; It works well in a dry environment. However, due to our "national conditions", most of them are installed on indoor equipment of 35 kV and below. In use, due to various reasons, the auxiliary transfer switch can not be switched normally, and the electromagnetic lock can not meet the sealing requirements and is corroded by moisture, so that the locking often fails. For outdoor high-voltage switchgear, electrical logic locking is mostly used to prevent false locking.
the logic locking of electrical circuit is to use the auxiliary contacts of circuit breakers, disconnectors and other devices to connect to the electrically operated circuits such as disconnectors or grounding knife switches to be locked, so as to realize the mutual locking between switching devices. It is characterized by complex secondary circuit, heavy workload of installation and maintenance, and often requires the assistance or cooperation of maintenance comrades in order to eliminate locking failure in time. The basic condition for its realization is the electrically operated equipment and mechanism. At present, most outdoor switchgear of 33 kV and below use this kind of locking device, but the actual operation situation is far from the ideal target. The main factors are poor sealing, corrosion and improper switching of the auxiliary switch.
Frequent failures of electrical locking, electromagnetic locking and mechanical locking often force the brake switching operation to stop, and sometimes the technical director has to be asked to forcibly use the "master key" to unlock the operation or remove the locking device. In order to improve the difficult situation of anti-misoperation locking and the need of safe production, a microcomputer anti-misoperation locking system composed of main computer, computer key, electrical coding lock and mechanical coding lock has been applied and popularized. Microcomputer anti-misoperation locking system is to lock the circuit breaker, disconnector, grounding knife switch (grounding wire) and auxiliary contact of switch cabinet door (or combined with primary wiring simulation board) by microcomputer coding lock. Input the operating program (rules) or locking logic of the switchgear into the program lock through the software system for switching operation, that is, add the microcomputer five-prevention contact in the operating power circuit of the electrically operated breaker or the ground knife mechanism box, and the error prevention function is independently completed by the microcomputer five-prevention system. However, it is required that the microcomputer five-prevention system should have measures to prevent "idling (missing items during operation)" At present, microcomputer locking developed by a company in Zhuhai with relatively perfect functions is widely used in China. The application and popularization of microcomputer anti-misoperation locking system are restricted by its complicated operation, slow speed, difficult installation of coded locks and individual crashes.
first of all, it is necessary to ensure that the circuit wiring is correct and the locking device works well in the same period; If the primary wiring of the equipment is changed, or the circuit wiring of the same period is changed, it is necessary to phase or check the phase in time; The operator should be familiar with the synchronization point and synchronization circuit of the unit, and put an end to putting two synchronization power switches into operation in parallel at the same time; Manual synchronization operation should be identified in the same period to realize synchronization locking; It is forbidden to forcibly close the power supply tie line without simultaneous identification or permission from the superior dispatcher.