JPS5828804B2 - Rapid scavenging device for electrical equipment containers with internal pressure explosion-proof structure - Google Patents

Description

[Detailed Description of the Invention] Conventionally, a solenoid valve has been used in a rapid scavenging device for a container of electrical equipment with an internal pressure explosion-proof structure. Alternatively, the solenoid valve may not operate due to a break in the solenoid coil.

In this case, for example, if the solenoid valve on the exhaust side does not open, there is a risk that the container of the electrical equipment, which has an internal pressure explosion-proof structure, will be damaged.

If the solenoid valve on the exhaust side opens normally but the solenoid valve on the supply side does not open, there is a risk that dangerous gas may enter from the solenoid valve on the exhaust side.

Either case is dangerous.

Furthermore, if an excessive current flows through the coil of a solenoid valve (for example, the force exerted by the valve), and as a result, the outside of the solenoid valve becomes overheated, there is a risk that the surrounding gas may explode.

Especially for gases of explosion class 3, these factors are quite dangerous, and although there are demands from industry, they have not yet been solved.

The present invention provides a system in which a pressure reducing valve is provided in the supply pipeline of a protective gas supply equipment that supplies air to a container of an electrical equipment having an internal pressure explosion-proof structure, and an exhaust gas valve is provided in the exhaust pipeline. This problem was solved by arranging an air supply gas valve, which is opened in conjunction with the opening of the exhaust gas valve, in parallel with the pressure reducing valve.

For electrical equipment with internal pressure explosion-proof construction, protective gas is pressurized into the container and the internal pressure is maintained at least 5 mm in water column above the pressure around the container to prevent surrounding explosive gas from entering the container. The factory electrical equipment explosion-proof guidelines published by the Ministry of Labor's Industrial Safety Research Institute require that the structure be such that energization begins after scavenging with a protective gas of at least 5 times the internal volume.
It is also required by the explosion-proof construction standards for electrical machinery and equipment and the electrical equipment technical standards.

The internal pressure explosion-proof structure is classified according to the internal pressure maintenance method, but the internal pressure explosion-proof structure applied to the device of the present invention continuously or intermittently pressurizes the leakage of the protective gas inside the container to maintain the pressure at a predetermined value. It has a sealed internal explosion-proof structure.

This type of protective gas supply equipment generally uses a compressor to inject pressurized air or nitrogen gas into the container to maintain the pressure. Since this can cause damage, the pressure must be reduced using a pressure reducing valve and then press-fitted into the container.

With this method, even if an exhaust gas valve that opens during air scavenging before startup is installed in the exhaust pipe and air is scavenged, the ventilation resistance of the pressure reducing valve is large, which limits the air supply flow rate, resulting in the time required for air scavenging before startup. This process takes a very long time, which has the disadvantage of increasing downtime.

Therefore, in the present invention, an air supply gas valve is arranged in parallel with the pressure reducing valve so as to form a short-circuit side path of the pressure reducing valve, and during air scavenging, the air supply gas valve is opened and pressurized air is directly injected into the container. In this way, the scavenging time is accelerated.

In this case, if the exhaust gas valve does not open at the same time as the air supply gas valve, an abnormal top will be applied to the container and the container will be damaged. The air supply gas valve provided in the container is linked with the air supply gas valve provided in the container, so that when the exhaust gas valve is opened, the air supply gas valve is opened, thereby preventing abnormally high pressure inside the container.

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates an electrical device housed in a container 2 of an electrical device having an internal pressure explosion-proof structure, and 3 and 4 indicate a supply pipe line and an exhaust pipe line of a protective gas supply equipment 5.

Reference numeral 6 indicates a pressure reducing valve provided in the feed pipe line 3, 8 indicates an exhaust gas valve provided in the exhaust pipe line 4, and I indicates a pressure reducing valve 6 which is arranged in parallel with the pressure reducing valve 6 to form a short-circuit side path for the pressure reducing valve 6. Gas valve for air supply, 10
is the main gas valve, 11 is the filter, 12゜13 is the moka meter,
9 is a valve drive device for the exhaust gas valve 8 and the air supply gas valve 7;
The air supply gas valve 7 is configured to operate when the exhaust gas valve 8 operates.

FIG. 2 shows a concrete structure of an embodiment of this configuration.

In FIG. 2, 8' (the same reference numerals indicate the same parts) is a gland cock, which is used for the exhaust gas valve 8 in FIG. 1.

7' is a mechanical valve; Fig. 1 shows a case where a mechanical valve is used as the air supply gas valve 7;
' comprises an actuator 14 consisting of a roller 19 and a lever 20.

9' is a valve drive device for the grand cock 8' and mechanical valve 7'; 15 is a handle for operating the valve drive device 9'; 16
is a rotary wheel for driving the gland cock 8', which has one end fixed to the gland cock 8' and the other end fixed to the operating handle 15.

Reference numeral 17 denotes a cam for driving the mechanical valve 7', which is fixed to the gland cock 8' and the driving rotation shaft 16 so as to open the mechanical valve 7' in conjunction with the opening of the gland cock 8'.

18 is a plunger for operating the mechanical valve 7'.

When the main gas valve 10 is in the open state, when the operation handle 15 is operated by hand (pneumatic pressure may also be used) to scavenge the container 2, the rotation of the rotation shaft 16 for driving the gland cock 8' causes The gland cock 8' is opened, the roller 19 is pressed by the rotation of the cam 17 for driving the mechanical valve 7', and the lever 20 presses the operating plunger 18, changing from the state shown in Fig. 3 to the state shown in Fig. 4, and the gland is closed. Cook 8
The mechanical valve 7' is also opened in conjunction with the opening of the mechanical valve 7'.

(In this case, the mechanical valve 7' is the gland cock 8'.
In that case, the cam 17 for driving the mechanical valve 7' may be shaped as shown by the dotted line in FIG. 3.

) When the grand cock 8' and the mechanical valve 7' are opened, the pressurized air (or nitrogen gas) passes through the filter 11 and the main gas valve 10, and then enters the pressure reducing valve 6 and mechanical valve T' which are arranged in parallel. The air is fed into the container 2 through the ground cock 8' and exhausted to the outside of the container 2 through the gland cock 8'.
Since the air resistance of ' is small, the flow rate of pressurized air is large, and therefore the air inside the container 2 is rapidly scavenged.

In this case, mechanical valve 7' gland control 5tsuk 8
′ has no ignition source, so there is no risk that the surrounding dangerous gas will explode.

Therefore, according to the present invention, it is possible to obtain a rapid scavenging device for electrical equipment containers having an internal pressure explosion-proof structure that is safe even in explosion class 3 environments, and its industrial value is significant.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention, Fig. 2 is a perspective view showing the main part in a concrete structure, and Figs. 3 and 4 show the state at the time of operation as shown in Fig. 3. FIG. 2... Container for electrical equipment with internal pressure explosion-proof structure, 5...
...Protective gas supply equipment, 3...Feeding pipe line,
6... pressure reducing valve, 4... exhaust pipe line, 8...
... Gas valve for exhaust, 7... Gas valve for air supply.

Claims (1)

[Claims] 1. In the pipeline of the protective gas supply equipment that supplies air to the container of electrical equipment with internal pressure explosion-proof construction, a pressure reducing valve is installed in the supply pipeline, an exhaust gas valve is installed in the exhaust pipeline, and an exhaust gas valve is installed in the exhaust pipeline. A rapid air scavenging device for electrical equipment containers with an internal pressure explosion-proof structure, in which a gas supply valve that opens in conjunction with the opening of the air supply gas valve is installed in parallel with a pressure reducing valve.