Improvement of mechanical interlock of the hottest

2022-08-18
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Improvement of mechanical interlock of high-voltage incoming cabinet with dual power supply

Abstract: from the two aspects of safety management and technology, we have discussed and reformed the principle, function and technology of operating mechanical interlock circuit, and put forward some opinions on the error prevention problem of 10kv High-voltage dual power supply in the distribution room of our hospital, which can provide innovative adhesive solutions to meet the short-term and long-term business development of customers, It can be used as a reference for professional technicians engaged in error prevention work in power distribution room

key words: anti misoperation mechanical interlock

I. problem raising:

in order to ensure the safe operation of the distribution room, improve the reliability of hospital power supply, and prevent the occurrence of double power supply incoming and accidents, setting mechanical interlock on the operating disconnector is an effective and feasible means to prevent misoperation and other accidents

the hospital is a first-class power user. In order to ensure the reliability of power supply in our hospital, the new distribution room (with a capacity of 630+630kva) of our hospital adopts dual power supply, one from 110kV north suburb to 10kV West City line, and the other from 110kV west suburb to west ring line. The power incoming cabinet adopts two sides of GG-1A (F2) -07zt high-voltage switchgear. In order to prevent accidents caused by misoperation of two power supplies, the css-1t mechanism of the operating mechanism of the disconnector (ggc/400a) of the two sides of the high-voltage switchgear adopts mechanical program locking and interlocking. According to the original design, this kind of mechanical program locking and interlocking is reasonable, but in the nearly half a year since the new distribution room was put into operation, However, there have been many accidents caused by the failure of switching operation of high-voltage disconnectors, such as the failure of normal and timely power supply and the damage of operating mechanism components. The power failure time was up to about 1 hour (on the evening of October 17, 2002). Fortunately, it did not cause casualties of operators and patients, but it had a very bad impact on the hospital. For this reason, the operators of the distribution room were punished, and the teams and departments were also affected to varying degrees

the reason for the accident is that the mechanical program lock is very inconvenient to unlock and close, and the switching operation procedure is complex due to the use of this mechanical program lock, which makes the switching operation unable to operate normally. Due to various reasons, the new distribution room in our hospital did not adopt microcomputer automatic control and electrical error prevention interlock, but adopted this kind of mechanical error prevention locking and interlock. Now this problem has occurred. It is impossible for the special power user such as the hospital to change this kind of mechanical error prevention into electrical error prevention or microcomputer control, because the hospital cannot change the operating structure of the high-voltage distribution cabinet by cutting off power for a long time (several days and ten days). In view of this situation, I can only start with the original design to see if I can design a set of improvement schemes, which can not only change the operation structure in a short time (1~2 hours), but also solve practical problems

II. Analyze the cause of the problem:

let's take a look at the "high voltage reverse electric operation procedure" of this mechanical program lock before improving the operating mechanism, so as to understand the unlocking and locking procedures of this mechanical program lock, so as to find out the cause of the accident

high voltage power down operation procedure

opening part

step 1: insert the "opening instruction board (green 21#)" into the "opening and closing transfer switch", turn the "opening and closing transfer switch" to the "opening" position, and remove the 21# key

step 2: put the 21 # key into the lock hole of the female knife brake and turn it to the off position Turn slightly and pull the "latch" to pull down the female knife brake

step 3: remove the 21 # key on the mother knife switch, insert it into the 21 # lock hole on the wire knife switch, turn it to the "open" position, check whether the 26 # key on the wire knife switch is in the "open" position, slightly turn the 21 # and 26 # keys, then pull the "plug", pull the wire knife switch, and remove the 21 # and 26 # keys. (the opening part of one side of the high-voltage switchgear is completed, and then the disconnector of the other side of the high-voltage switchgear is closed)

closing part

Step 4: insert the keys 21 # and 26 # into the lock holes 21 # and 26 # on the line knife switch of the other side of the high-voltage switchgear, turn it to the "closed" position, pull the pin, and push the line knife switch

step 5: remove the 26 # key on the lower knife switch, put it into the 26 # lock hole on the female knife switch, turn it to the "closed" position, pull out the "latch" and close the female knife switch

step 6: take down the 26# key on the female knife switch, put it on the opening and closing transfer switch, transfer it to the "on" position, release it immediately, and the transfer switch will automatically rebound to the vertical position

as shown in the figure is the schematic diagram of this kind of disconnector. In the figure, it can be seen that the wire knife switch and the mother knife switch of the disconnector are each equipped with a lock. There are two lock holes 22# 26# on the wire knife switch, and there are 21# lock holes on the mother knife switch. Use the 21# 26# key to open these four locks respectively. In the opening part, the master knife switch must be disconnected first. The 21 # key must still be in the "opening" position at the 12th European gasification conference held in the Netherlands a few days ago (otherwise it will not be able to insert into the 21 # lock hole of the wire knife switch). Remove the 21 # key and insert it into the 21 # lock hole of the wire knife switch. The lock of the wire knife switch must use the 21 # and 26 # keys to cooperate with each other to open the latch and disconnect the wire knife switch. The closing part closes the wire knife switch first, and then closes the master knife switch, It also requires the close cooperation of 21 # 26 # key to open the latch and close the knife brake. From this, it can be seen that this mechanical program lock must be closely cooperated. As long as one step is stuck, other steps cannot be carried out, resulting in the failure of normal switching operation accidents

our operators are required to memorize this complex high-voltage switching operation procedure. For this reason, we have conducted several training and examinations. We also printed and pasted the operation procedure on the panel of the high-voltage switchgear, which can be seen at a glance, so as to prevent mistakes at any time. Reasonably speaking, such a careful arrangement should not cause problems, but it still did not prevent the occurrence of accidents. As an electrician squad leader, I was anxious in my eyes. The newly-built distribution room could not be changed to electrical error prevention. I can only start with the mechanical structure of the disconnector to see whether we can not only give up using this mechanical program lock, but also follow several principles of high-voltage power switching:

1. The disconnectors of two high-voltage switchgear are interlocked with each other. (for example, suppose there are two high-voltage disconnectors A and B, a is in the closing state and B is in the opening state. Now it is necessary to close the B disconnector, then the a disconnector must be disconnected first, and then the B disconnector can be closed. When the B disconnector is closed, the a disconnector must also be locked so that it cannot be closed)

2, breaking the disconnector ----- the denominator disconnector must be opened first, and then the line disconnector

3. Close the disconnector ----- the line knife switch must be closed first, and then the bus knife switch

III. my solution to the problem:

according to these principles, I have carefully studied the mechanical structure of the disconnector and designed a set of changes after repeated thinking. The figure is as follows:

as can be seen from the figure, first of all, I changed the original mechanical program lock into an ordinary spring-loaded lock, and then designed an interlocking plug rod according to the four perforations on the rotating shaft of the four handles of the two disconnectors, There is a handle in the center of the interlock plug rod. Two collars are installed at two places of the distribution cabinet a and B as the support points of the interlock plug rod. Two lock holes are drilled at the two ends of the small fault of the interlock plug rod PS. many material testing machines (the central position between the wire knife switch and the mother knife switch). Pulling the interlock plug rod by hand can slide between the four holes of the disconnector

the design principle of this improved scheme is based on several principles of high-voltage power down:

1. Prevent misoperation, and replace the mechanical program lock that causes the accident with an ordinary elastic lock

2. The disconnectors of the two switch cabinets are interlocked with each other, as shown in the figure. The interlock plug rod I designed is to ensure that the two disconnectors are interlocked with each other. (when the isolating switch of the west line of the city is in the closed state, because the interlocking plug rod is at the hole of the rotating shaft of the isolating switch of the west ring line, the isolating switch of the west ring line cannot be closed at this time. Only disconnect the isolating switch of the West line of the city first, pull the interlocking plug rod to completely exit the two holes of the rotating shaft of the isolating switch of the west ring line, and insert the hole of the rotating shaft of the isolating switch of the west line of the city at the same time. At this time, the interlocking plug rod locks the isolating switch of the west line of the city so that it cannot be closed The interlock plug rod also fails to act after closing the West Ring Line disconnector)

the operation procedure of this scheme is as follows: (assuming that the west ring line is stopped now and the west ring line is powered)

1. Pull out the latch of the elastic lock on the mother knife switch of the West Ring Line disconnector, pull down the mother knife switch, and then pull out the latch of the elastic lock on the outlet knife switch, and pull down the lower knife switch

2. Open the padlock at the right end of the interlock plug rod, pull the handle of the interlock plug rod, and pull the interlock plug rod out of the two holes of the rotary shaft of the disconnector of the west ring line. At the same time, the interlock plug rod is inserted into the hole of the rotary shaft of the disconnector of the west city line, and then lock the padlock at the left end of the interlock plug rod. The west city line is separated from the lock hole between the line switch and the mother switch

3. Open the latch of the elastic lock on the line knife switch of the West Ring Line disconnector, close the upper knife switch, then open the elastic lock latch on the female knife switch, and close the female knife switch

the improvement of this scheme not only simplifies the switching operation procedure, but also is convenient and reliable. It has been highly praised by the manufacturer of high-voltage switchgear, and has been installed and manufactured by the manufacturer according to my design scheme. So far, no operation accident has occurred in the actual work of switching operation in the future, ensuring the safe operation of the distribution room, preventing the occurrence of double power incoming line accidents, and improving the reliability of hospital power supply, Practice has proved that setting mechanical interlock on the operating disconnector is an effective and feasible means to prevent accidents such as misoperation. My improved scheme can be used for reference by colleagues with the same or similar situations

IV. discussion on error prevention work:

in the face of countless bloody lessons, combined with the practice of electrical operation at home and abroad, in order to effectively prevent personal and major equipment accidents caused by the misoperation of operating electrical equipment, the requirements of "five prevention" of electrical equipment were put forward as early as 1990, and the principles of management, operation, design and use of universal testing machine for electrical error prevention were stipulated in the form of laws and regulations

five prevention functions refer to:

(1) prevent the circuit breaker from being opened and closed by mistake

(2) prevent on-load opening and closing of disconnectors

(3) prevent the live hanging (closing) of grounding wire (grounding knife switch)

(4) prevent the breaker (disconnector) with grounding wire (grounding knife switch) from closing

(5) prevent entering the charged Bay by mistake

electrical error prevention is an error prevention function based on the secondary operation circuit, which is generally realized through the interlocking of the auxiliary contacts of the switch and the knife switch. Mechanical error prevention is an error prevention function based on the primary operation circuit, which is generally realized through the interlocking of the main contact of the switch and the knife switch

according to the "Regulations", the design of error prevention device should follow the principle that all high-voltage electrical equipment that may cause misoperation should be equipped with mechanical error prevention device and corresponding error prevention electrical locking circuit

based on this principle, the "five prevention" Regulations are put forward, because from the process of misoperation, misoperation is composed of three parts, which are caused by the misoperation of operation duty personnel, maintenance personnel and other personnel

the misoperation of operators mainly occurs in the wrong pulling, wrong closing of knife switches and switches, and wrong entry into intervals, which are easy to cause malignant accidents. Mechanical error prevention is a positive measure to prevent such accidents. It can only meet the operation requirements of the operation personnel on duty, and can not completely solve the problem of misoperation of maintenance personnel and other personnel. For maintenance personnel, misoperation mainly occurs in maintenance and test

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