1. Overview

The explosion-proof feed switch for mining is widely used underground in coal mines. Breaking and connecting the connections between superiors and subordinates in the distribution system provides protection for the power supply of the next level and facilitates maintenance of the next level line. The explosion-proof feature of this product is that its shell has explosion-proof and explosion resistance, which plays an important role in preventing electric sparks from igniting and igniting mine gas, and ensuring personal safety. However, these measures still cannot prevent the occurrence of gas and coal dust explosions caused by faulty electric sparks. From past accidents, it can be seen that electric sparks are the main cause of gas explosions and personal electric shock accidents. That is to say, there are still defects in the explosion-proof performance of ordinary explosion-proof electrical equipment used underground in coal mines.

The explosion-proof structure of ordinary mining explosion-proof feed switches is divided into two parts: the wiring chamber and the main chamber, which are two chamber explosion-proof. The main chamber has electrical and mechanical interlocking functions, while the wiring chamber does not have any locking function. It is precisely because of this defect that when operators accidentally violate regulations, they may open the wiring chamber and operate with power. Not only will it cause personal injury, but it is more likely that gas explosion accidents will be caused by electric sparks generated during live working. Since the place of use is an explosive gas environment, the Coal Mine * * Regulations clearly stipulates that live maintenance is not allowed underground and electrical equipment shall be relocated. However, in the actual production process, underground electricians often engage in illegal live working. Nowadays, many coal mines use explosion-proof feed switches, only the explosion-proof chamber has a mechanical locking device, which cannot be opened without cutting off the power supply. However, any locking device in the wiring chamber can also open the wiring chamber under live conditions.

The explosion-proof and essential * * type graded locking technology can greatly improve the explosion-proof level of coal mines, and can prevent incorrect power transmission by superiors during live maintenance and repair. A new type of mine explosion-proof and essential graded locking feeder switch has been successfully developed to address the technical defects of mechanical and electrical locking not being achieved in the wiring cavity of ordinary mine explosion-proof switches. Realized the power outage and hierarchical locking when opening the wiring chamber cover. Essentially, it avoids opening the wiring chamber cover for live working and mistakenly transmitting power to the previous level.

2. Characteristics of mine explosion-proof and essential * * type graded locking feed switch:

The mining explosion-proof and essential * * type graded locking feed switch divides the wiring chamber into two independent explosion-proof wiring chambers: the power inlet chamber and the load outlet chamber. If any wiring chamber is opened under live conditions, a new type of switch can be operated by a locking mechanism to cut off the power of the switch poles and lock them (the load outlet chamber is disconnected and locked at the current level switch, and the power inlet chamber is disconnected and locked at the higher-level switch) before the wiring chamber is detonated.

a. The incoming cavity is opened and locked by a set of switch values (normally open contacts) to open and lock the upper level feed switch (the upper level feed has a dedicated fault point for hierarchical locking), making the operation simple and reliable.

b. The outlet chamber locks the local protection through a set of switch values (normally open contacts), achieving switch tripping and locking.

c. During normal power outage maintenance, lock the higher-level switch when opening the incoming cavity to prevent power transmission

3. The principle of mining explosion-proof and essential * * type graded locking feed switch:

a) Open the locking cover plate on the incoming side of the wiring chamber, and the upper feed switch will be powered off and locked; Before opening the wiring chamber inlet cover plate (2; see attached figure), the graded locking cover plate (1) on the inlet side of the wiring chamber must be opened first; When opening the grading locking cover plate (1) of the wiring chamber, the grading locking rod (4) of the incoming chamber cover plate moves up, and at the same time, the grading locking rod (6) of the incoming chamber moves up. A set of switch values on the locking button switch (10) (passive 250V/2A normally open contacts act and close) send a tripping signal to the superior switch through the locking wire (user connection required), The higher-level switch (switches without hierarchical locking function can be achieved through other fault functions) fails to trip and lock;

b) Open the locking cover plate of the wiring chamber outlet chamber, and open and lock the local feeder switch; Before opening the wiring chamber outlet chamber cover plate (2), the outlet chamber grading locking cover plate (1) must be opened first. When opening the outlet chamber grading locking cover plate (1), the outlet chamber cover plate grading locking rod (4) moves up, and at the same time, the outlet chamber grading locking rod (6) moves up, and the locking button switch (10) acts; A set of normally open points on the locking button switch (10) closes, the feed switch protector acts, and the feed switch trips and locks (the display screen shows a graded locking fault).

4. Application

The mine explosion-proof and essential * * type graded locking feed switch is widely and flexibly used; It can be used in conjunction with feed switches and other switches of different models, manufacturers, and models;

1. The graded locking feed switch serves as the main switch, while the branch switch (sub switch) uses feed switches without graded locking function; The main feeder switch has a graded locking function in both the inlet and outlet cavities, but there is no graded locking function for lower level switches.

2. The hierarchical locking feed switch serves as a branch switch (sub switch), while the higher-level switch uses feed switches without hierarchical locking function;

a. The branch hierarchical locking feeder switch only uses the hierarchical locking function of the outgoing cavity; That is, open the outlet cavity of any branch hierarchical locking feed switch. This switch trips and locks (the display screen shows hierarchical locking fault). When opening the inlet cavity of any branch hierarchical locking feed switch, it must comply with the "Coal Mine * * Regulations", manually stop the higher-level switch power and manually lock it.

b. If the grading locking function of the incoming cavity is used, the grading locking function of the superior switch can be achieved by utilizing the idle fault points of the superior switch. The grading locking switch values of all branch switches (sub switches) can be connected in parallel to the idle fault points of the superior switch (the user needs to record the fault information), and the outgoing cavity of any branch grading locking feeder switch can be opened. This switch trips and locks (the display screen shows the grading locking fault), Open the inlet cavity of any branch hierarchical locking feed switch, and the superior switch trips and locks (the display screen displays the recorded fault information).

3. Both the main switch and branch switch (sub switch) use feed switches with graded locking function; Connect the hierarchical locking switch values of all branch switches (sub switches) in parallel to the fault point of the hierarchical locking of the main switch. Open the inlet cavity of any branch hierarchical locking feed switch, and the main switch trips and locks (the display screen shows a hierarchical locking fault); Open any branch hierarchical locking feed

According to the above characteristics of the graded locking feed switch, the correct use of its function can fundamentally prevent gas explosions and electric shock accidents caused by incorrect or illegal operation, opening the wiring chamber of the graded locking feed switch and generating electric sparks.

If the graded locking function unexpectedly fails:

a. The locking switch has always been in the locking state, just remove the locking wire;

b. The locking switch value has been in the unlocked state, and only the hierarchical locking function has failed;

It will not have any impact on this switch and distribution system.

In summary, promoting the use of this technology can elevate the performance of coal mine electrical equipment to a new level. Therefore, this technology plays a very important role in ensuring the production of coal mines.