JPH097689A - Simple explosion-proof electric drum - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an inexpensive electric drum with a simple structure that can be used in an explosion-proof area. [Structure] A gas detector 5 for supplying gas to outlets 6A and 6B of an electric drum through an earth leakage breaker 2 placed in a non-explosion-proof area and detecting gas in the explosion-proof area.
A and 5B are provided, and the leakage breaker is cut off by the gas detection signals from the gas detectors 5a and 5b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple explosion-proof electric drum.

[0002]

2. Description of the Related Art Conventionally, when electric equipment such as recorders, measuring instruments, lighting fixtures, and electric tools is temporarily used indoors or outdoors at work sites, laboratories, etc., the power cord is too short or an outlet at the site is used. An electric drum is used when the position of is inconvenient.

In the electric drum, a cable of several tens of meters is wound around the drum. A dedicated plug, which is separately provided, is inserted into an outlet on the spot, and the cable is unwound from the drum by a required length, and the drum is electrically operated. It is a so-called extension cord that is carried near the place of use, and when the plug of the electric device is inserted into an outlet built into a part of the drum, electric power is supplied to the electric device through the cable.

By the way, the conventional electric drum can be used in a so-called non-explosion-proof area where there is no risk of abnormal ignition due to flammable gas, but in the explosion-proof area, sparks are generated when the plug of the electric device is inserted into or removed from the electric drum outlet. Can not be used for.

[0005]

Therefore, an electric drum having a structure that can be used in an explosion-proof area has been developed.
Such an explosion-proof electric drum is inconvenient to handle because it has a large and heavy mold and is very expensive, so it cannot be used easily. In addition, since the explosion-proof electric drum uses a plug with a special structure and shape, it cannot be inserted into a general outlet for use.

The present invention has been made in view of the above points, and provides an inexpensive electric drum having a simple structure which can be used in an ordinary outlet and can be used in an area such as a construction site or a laboratory where an abnormal ignition may occur. With the goal.

[0007]

In order to solve the above problems, the present invention has at least one electrical equipment connection outlet, one end of a cable wound on a drum is connected to the outlet, and the other end of the cable is connected. In the electric drum supplied with power from, in addition to connecting the earth leakage breaker that operates in the non-explosion-proof area to the other end of the cable, provide a gas detector that detects a flammable gas above the specified concentration in the explosion-proof area, the gas The leakage breaker is cut off by the gas detection signal of the detector. The gas detector may be built in the drum or may be connected to the electric drum by a cable.

Further, according to the present invention, a portion of the output signal line of the gas detector between the electric work drum and the earth leakage breaker is put together with the cable into one collective cable.

[0009]

[Function] When the gas detector detects a flammable gas with a concentration higher than the specified concentration in the explosion-proof area, the gas detection signal activates the gas detection control earth leakage breaker placed in the non-hazardous area, and the power is supplied to the cable by opening it. Be cut off. Thus, there is no possibility of abnormal ignition due to an arc because electric power is not supplied to the electric equipment inserted in the outlet of the electric drum.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a view for explaining the schematic structure of a simple explosion-proof electric drum according to the present invention.

The simple explosion-proof electric drum 10 according to the present invention is used in an explosion-proof area partitioned by a partition 8 as shown in FIG. There are explosion-proof areas where flammable gases such as natural gas and hydrogen are present in test fields and laboratories, and the explosion-proof areas are prone to abnormal ignition due to arcs and the like generated by the opening and closing operations of switches.

The simple explosion-proof electric work drum 10 of the present invention has one or a plurality (two in the illustrated embodiment) of outlets 6A and 6B incorporated therein and one gas detector 5A incorporated therein. However, a power cable having a length of several tens of meters is wound around the outer circumference of the drum, one end of the power cable is electrically connected to the outlets 6A and 6B, and the other end on the power source side is a non-contact outside the partition 8. It is connected to one terminal b of the ELB 2 with a gas detection control leakage breaker, ie, an external trip control, which is placed in the explosion-proof area. The other terminal a of the earth leakage breaker 2 is connected to a power source (AC 1
00V) 1. On the other hand, a control line 3 is output from the gas detector 5A built in the drum of the electric work drum 10 toward the earth leakage breaker 2, and the control line 3 is connected to the internal circuit of the earth leakage breaker 2. When the gas detection signal from the gas detector 5A is sent to the earth leakage breaker 2 via the, the contact piece inside the earth leakage breaker 2 moves due to the operation of the internal circuit, so that the terminals a and b are separated from each other. The power supply circuit to the electric drum 10 is cut off.

A power cable 4 between the earth leakage breaker 2 and the electric work drum 10, the earth leakage breaker 2 and the gas detector 5A.
The control line 3 between and is integrated into one cable as a 5-core cable including the ground wire, for example. Instead of incorporating the gas detector in the electric drum 10 like the gas detector 5A, the gas detector is connected by a wire 3 as shown by a dotted line 5B and placed at a position near the electric equipment 7 used away from the electric drum 10. May be. When the electric drum 10 itself can be brought close to the electric equipment 7 to be used, it is convenient for the gas detector to be built in the drum, but of course both built-in type and separated type may be used. As the gas detector, a high-sensitivity semiconductor gas sensor capable of operating at a gas concentration of about ¼ of the lower ignition limit is used.

The earth leakage breaker 2 is an alternating current 1 in the non-explosion proof area.
A power line 4 is connected to the 00V power source 1, and a cord 4b having a length of 1 to 2 m attached to the electric device 7 is connected to the outlets 6A and 6B of the electric drum 10 placed in the explosion-proof area (the embodiment shown in the drawings). But only the outlet 6A is used.) The earth leakage breaker 2 is connected to the outlets 6A and 6B by the power cable 4 and is connected to the gas detector 5A or the gas detector 5B by the control line 3. The electric device 7 includes, for example, a recorder, measuring instruments, lighting equipment,
For example, an electric tool. The cable wound around the electric drum may be a single 5-core cabtyre cable in which the control line 3, the power cable 4 and the ground line are combined.

Next, the method of use and operation of the electric drum of the present invention having the above construction will be described.

Connect the earth leakage breaker 2 to the AC 1 in the non-explosion proof area.
It is connected to the 00V power source 1 by the power line 4a, and the electric drum 1
While unwinding the power cable 4 wound around the drum outer periphery of No. 0, carry the electric drum 10 near the place where the electric equipment 7 is used in the explosion-proof area and place it in an appropriate place, and connect to the outlet 6A in the explosion-proof area. Insert the plug of the device (power tool) 7.

However, if a flammable gas having a sensitivity higher than the specified sensitivity of the gas detector 5A is present in the explosion-proof area where the electric drum 10 is placed at this time, the gas detector 5A detects the flammable gas and the control line 3 is connected. A gas detection signal is sent to the control earth leakage breaker 2 via the. As a result, the earth leakage breaker 2 operates and the power is opened by the earth leakage breaker as shown by the solid line in FIG.
It is opened and the power supply circuit from the power supply 1 is cut off. As a result, the power source 1 is connected to the outlets 6A and 6B of the electric drum 10.
Voltage is not applied. Therefore, in this state, the plug of the electric device (for example, electric power tool) 7 is connected to the electric drum 1.
No sparks are generated when plugged into or unplugged from the 0A outlet 6A, and even if flammable gas is present in the explosion-proof area, there is no danger of abnormal ignition and it is safe.

On the other hand, when there is no combustible gas in the explosion-proof area, no gas detection signal is output from the gas detector 5A, so the terminals a and b of the earth leakage breaker 2 are closed as shown by the broken line in the figure. Since it is still formed, the power source 1 through the power line 4a and the power cable 4 to the outlet 6A,
A voltage is applied to 6B. Therefore, if the plug of the electric device 7 is inserted into the outlets 6A and 6B of the electric drum 10, power is supplied and the electric device 7 can be used.

[0020]

As described above, according to the present invention, the gas detection control in which the power cable is wound around the drum and the conventional electric drum having the outlet for connecting the electric equipment is connected to the power source in the non-explosion-proof area. An earth leakage breaker and a gas detector placed in the explosion-proof area to detect the presence of flammable gas above the specified concentration are newly provided, and the gas detection control earth leakage breaker is opened by the gas detection signal from the gas detector. With this configuration, when flammable gas exists in the explosion-proof area, power supply to the electric drum is cut off, so that the electric device can be safely used in the explosion-proof area. The electric drum according to the present invention has a simple structure, is light in weight and inexpensive, and can be used with a general outlet, so that it is useful as a simple explosion-proof electric drum.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a schematic configuration of the present invention.

[Explanation of symbols]

 1 Power Supply 2 Gas Detection Control Leakage Breaker 3 Control Line 4 Power Cable 4a Power Line 4b Code 5A Gas Detector 5B Gas Detector 6A Outlet 6B Outlet 7 General Use Equipment 8 Partition 10 Simple Explosion-Proof Electric Drum

Claims (4)

[Claims] 1. An electric drum having at least one electrical device connecting outlet, wherein one end of a power cable wound on a drum is connected to the outlet, and power is supplied from the other end of the power cable. A short circuit breaker that operates in a non-explosion proof area is connected to the other end of the cable, and a gas detector that detects combustible gas with a concentration above the specified level in the explosion proof area is provided.The leak breaker is detected by the gas detection signal of the gas detector. Simple explosion-proof electric drum characterized by being configured to shut off. 2. The simple explosion-proof electric work drum according to claim 1, wherein the gas detector is built in the drum. 3. The simple explosion-proof electric work drum according to claim 1, wherein the gas detector is connected to the drum by a wire. 4. The part of the output signal line of the gas detector between the drum and the earth leakage breaker is combined with the power supply cable into one collective cable. Simple explosion-proof electric drum.