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Several Problems Should Be Paid Attention to in Electrical Operation

Nov. 04, 2020

Emergency Stop LockoutElectrical Panel Lockouts supplier introduces several issues that should be paid attention to in electrical operation.

1. The electric test needs to be carried out with special tools such as a multimeter and an electroscope

The power system has strictly prohibited the use of self-made and crude card lights for electrical testing; the correct low-voltage electrical testing method is to use special tools such as multimeters and electroscopes. Because of the large internal resistance of the multimeter (voltage range) and the electroscope, the current flowing through the tester is small and the response is sensitive, and they are professionally made, safe and reliable, and easy to use.

2. The exposed metal part of the electroscope should not be too long

The exposed metal parts of the electroscope, the test pen of the multimeter, etc. should not be too long. If the exposed metal part of the electroscope is too long and the user is not careful, it will cause the charged metal part to touch other charged objects or the equipment shell, causing a short circuit; if the tool is tilted during use, it may cause a short circuit between phases. Come with serious consequences. It is recommended that the bare metal part of the high-voltage electroscope should not exceed 10mm.

3. Wear insulating gloves when closing the fuse (fuse)

The "Safety Regulations" clearly stipulates that insulating gloves should be worn when closing the fuse, but some workers ignore this important link for convenience. When disconnecting and closing the fuse with bare hands, it is easy to touch the live parts and cause electric shock. When using the card holder to break and close the fuse, because the spring of the fuse seat is tight, uneven force during operation may also cause the hand to shift to both sides and touch the live part. If you wear insulating gloves, you can avoid electric shock accidents.

4. Prevent the load and power transmission of the trolley switch. The consequences of pulling and power transmission with load are disastrous, ranging from damage to equipment and endangering personal safety.

Full preparations should be made before power transmission. In addition to measuring the motor insulation and checking, and checking the name (number) of the switchgear, the detection of the switch cannot be ignored. When the trolley switch is in the inspection position, use the resistance file of a multimeter to measure the resistance of the upper and lower contacts of the trolley switch and the resistance of the interphase contacts. If the resistance is zero, it proves that the switch has a short circuit in the closing position or between the switch phases, and the trip switch must be activated or troubleshooting before the switch can be pushed into the inspection position.

The inspection work before power-on is essential, and the power-on operation can only be performed when the equipment stops running and the switch is opened. In addition to checking the name (number) of the switch device before powering on, check the signal indicator of the switch, the position indicator of the switch, the ammeter indication of the load is zero, and whether the watt-hour meter has stopped, and the switch must be pulled out. First jump on the switch in place.

5. The stop and power transmission of the trolley switch should be carried out in the correct operation sequence

1) Wrong operation sequence

Many electrical operators believe that the operation sequence when the trolley switch is powered on is:

(1) Check the equipment and check that the switch is in the off position;

(2) Pull off the switch's closing fuse and operation fuse, and unplug the secondary circuit plug of the trolley switch;

(3) Pull out the switch to the inspection position.

The sequence of operations when powering up is:

(1) Check equipment;

(2) Push the switch to the working position;

(3) Plug in the secondary circuit plug of the trolley switch, and send the switch's closing insurance and operation insurance.

This is mainly because:

(1) The wiring of the secondary circuit plug of the trolley switch is generally not long. To pull the switch to the inspection position, the secondary circuit plug of the switch must be pulled first; the secondary circuit plug of the trolley switch is under inspection and repair The location is not plugged in either.

(2) This method of operation is taught by the master. But this kind of operation sequence is wrong and violates the technical principle of switch operation that "switches control and protect the power supply must be opened after all the circuit breakers are operated to prevent loss of protection during misoperation."

The operation of pulling the trolley switch from the working position (or pushing it into the working position) is actually the operation of pulling and closing the knife switch of the trolley switch. Pulling off the operating safety of the switch and unplugging the secondary circuit plug of the trolley switch is actually to withdraw the operating power and protection circuit of the switch. "First pull out the operating safety of the switch, unplug the secondary circuit plug of the switch, and then pull the trolley switch out of the working position; or first push the switch to the working position, then plug in the secondary circuit plug of the switch, and send it for operation The operation of "insurance" actually makes the knife switch of the trolley switch lose its protection during the pulling and closing process. Although the anti-terror functions of the current trolley switches are relatively complete, there is generally no problem with the operation. However, it should not be too dependent on the anti-terror function of the switch itself, let alone violate the technical principles of switch operation because the switch has the anti-terror function. Because once the anti-misoperation function of the switch fails, the switch will not open when the load is pulled or the load is sent. The lighter will damage the equipment, and the severer can cause personal injury and death, with serious consequences.

2) Correct order of operating principles

The correct operation sequence is: when the trolley switch is powered on, first pull off the closing fuse of the switch, pull the switch to the test position, then pull off the operation fuse of the switch, the secondary circuit plug, and then pull the switch to the inspection position; When the switch is powered on, first push the switch to the test position, insert the secondary circuit plug of the switch, and put the operating safety on, then push the switch to the working position. Because when the trolley switch is in the test position, the moving and static contacts of the switch switch are in a separate state. When the switch is pulled from the working position to the test position or pushed from the test position to the working position, the operation of the switch is safe and the second time The loop plug is in the working position, which can ensure that the protection will not be lost during the operation of pulling and powering on the trolley switch. Moreover, when the switch is in the test position, the wiring length of the switch secondary circuit plug is also sufficient.

6. The steps to check the equipment on the spot before power transmission are indispensable

In addition to checking that the power transmission equipment is in the standby state and measuring the insulation of the power transmission equipment before power transmission, the actual condition of the equipment must also be checked on the spot. An electrician in a factory was paralyzed and failed to check the equipment carefully when sending power after a coal mill overhaul. He only checked the motor insulation and checked whether there was a work ticket, and then sent the coal mill. Machine power supply. As a result, a three-phase short-circuit accident occurred when the coal mill was started. The reason is that the maintenance personnel shorted the three-phase connection of the coal mill motor. If the equipment can be carefully inspected on the spot before power transmission, this accident can be completely avoided. It can be seen that on-site inspection of the equipment before power transmission is essential.

7. Fill in the operation ticket when closing the grounding switch or installing the temporary grounding wire

Some electrical operators, especially some masters, believe that the single operation of closing the grounding switch or installing a temporary grounding wire is a simple operation, and there is no need to fill in an operation ticket. What's more, it is believed that such a simple operation can be done by one person without supervision.

As everyone knows, the operation of closing the grounding switch or installing the temporary grounding wire is a dangerous operation in electrical operation. Once an accident occurs, the impact will be great and the consequences will be serious. It is not uncommon for the electric power system to connect the grounding knife (connecting the grounding wire) accident, and it is classified as a vicious misoperation accident. And the operation of closing the grounding switch or installing a temporary grounding wire is not a single operation. It at least includes: (1) checking the name and number of the equipment; (2) checking whether the conditions for closing the grounding switch or installing the temporary grounding wire are available ( The switch has been disconnected, the knife switch has been opened, and it is indeed isolated from the live part); (3) electrical inspection and discharge; (4) several steps such as closing the grounding knife switch or installing a temporary grounding wire.

8. Do not do anything unrelated to the operation during operation. Doing things that are not related to the operation during the operation often interrupts the operation thinking. Many operation accidents are caused by the operations that are not related to the operation.

9. You must terminate the operation when you encounter any questions or have questions about the operation items during the operation, and send a message to the operator to clarify before continuing the operation.

10. Strictly abide by the anti-misoperation locking management regulations, unless the problem of the anti-misoperation locking device itself has not been dealt with properly, the introduction of the anti-misoperation locking device is prohibited under normal circumstances.

The misoperation of electrical operation and the operation of heat engine is also special, that is, it cannot be reversed. According to statistics, most misoperation accidents are often accompanied by equipment problems or because personnel are not fully familiar with the equipment. The anti-misoperation locking device for exiting electrical equipment is, in a certain sense, the protection of exiting equipment, and everyone must pay attention to it.


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