JPH04347529A - Electric shock preventing circuit - Google Patents

Abstract

PURPOSE:To protect a worker against electric shock in live area (access area). CONSTITUTION:When a worker stretches his hand into an access area 101 for the purpose of maintenance, optical path between a projector 3 and a light receiver 4 is blocked. The light receiver 4 notifies blockage of optical path to a microprocessor 6 and a current interrupting switch 5 is opened by means of a switching command circuit 7 and a switching operating unit 8. Consequently, current flow through a current path 102 is interrupted automatically, and an indicator lamp 9 is lighted. When the arm of the worker gets out of the access area 101, current flow through the current path 102 is reset automatically in reverse manner and the indicating lamp 9 unlights.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to electric shock prevention circuits, and in particular, there is a risk of electric shock due to contact with workers near the primary input terminals of electrical equipment power supplies or in high current paths such as remote control distribution boards. This invention relates to an electric shock prevention circuit used in certain cases.

0002

[Prior Art] Conventionally, for electrical equipment, etc., which has a conductive part connected to a large current path within the access area of the worker, a protective shield enclosure is attached to the conductive part using screws, etc., and the worker directly attaches the protective shield to the conductive part. The structure prevents contact with conductive parts to prevent electric shock.

0003

However, with conventional electric shock prevention means, the protective shield may come off or move due to damage or loosening of the screws during equipment maintenance or the like. Furthermore, since this protective shield significantly limits the work area, it may be necessary to work in an awkward position. As a result, workers often accidentally come into contact with the conductive parts and receive an electric shock, which is very dangerous.

The present invention has been made in view of the above problem, and its purpose is to avoid limiting the working area of the conductive portion that is connected to the large current path, and to
An object of the present invention is to provide an electric shock prevention circuit that can reliably prevent electric shock during work.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a floodlight that emits sensor light around a conductive portion of an access area, and a floodlight that is disposed facing the floodlight with a common optical axis at a constant interval. a light receiver that outputs different signals when the sensor light from the light receiver is shielded and when the shielding is released; and a current interrupting means that cuts off the current flowing through the current path when the sensor light to the light receiver is shielded. , and a current return means for returning current to the current path when the shielding of the sensor light is released, constitutes an electric shock prevention circuit.

Further, in the electric shock prevention circuit described above, a lighting indicator and a lighting display execution circuit that drives the lighting indicator are provided, and when the current in the current path is blocked, the lighting indicator is lit; When the condition is restored, the lighting indicator is turned off to alert workers.

[0007]

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

FIG. 1 is a block diagram of an electric shock prevention circuit according to an embodiment of the present invention. In the figure, 101 is an access area, 1
Reference numeral 02 indicates a current path, and reference numeral 103 indicates a conductive part that a worker may come into contact with. 2 constitutes an electric shock prevention circuit.

[0009] The current cutoff circuit section 1 has an access area 10
A projector 3 that emits sensor light such as invisible light, such as infrared light, is placed around the conductive portion 103 of the projector 1, and the projector 3 is arranged to face the projector 3 with a common optical axis at a constant interval, and is used to block the sensor light from the projector 3 and to a light receiver 4 that detects the release of shielding; a current interrupting means that cuts off the current flowing through the current path 102 when the sensor light to the light receiver 4 is shielded; 102, and current restoration means for restoring the current. Note that the sensor light may be visible light if it does not cause an obstacle to the worker.

Here, the current interrupting means and the current restoring means include, for example, a current interrupting switch 5 inserted into the current path 102 and a microprocessor 6 connected to the light receiver 4.
It is composed of a switch opening/closing control circuit that exchanges signals with the microprocessor 6 and controls opening and closing of the current cutoff switch 5, that is, a switch opening/closing instruction circuit 7 and a switch opening/closing actuator 8.

The microprocessor 5 takes the output signal of the photoreceiver 4 as an input signal, and outputs a cutoff control signal when the sensor light to the photoreceiver 4 is blocked, and also outputs a cutoff control signal when the photoreceiver 4 receives the sensor light again. In this case, a return control signal is output. Further, when receiving an opening confirmation signal and a closing confirmation signal, which will be described later, a lighting control signal and a lighting control signal are output.

The switch opening/closing instruction circuit 7 outputs a switch opening command and a switch closing command when receiving a cutoff control signal and a return control signal from the microprocessor 6, respectively, and a switch opening/closing actuator 8 outputs a switch opening/closing command. The current cutoff switch 5 is driven to open or close according to each command from the open/close instruction circuit 7. When the current cutoff switch 5 is actually opened or closed, the switch opening/closing actuator 8 confirms this state and sends it to the microprocessor 6 via the switch opening/closing instruction circuit 7.

The current interrupt circuit section 1 also includes a lighting indicator 9.
and a lighting display execution circuit 10. The lighting indicator 9 is
It is provided near the access area 101 in a part that can be seen by workers, and selectively turns on and off the light.The lighting display execution circuit 10 receives a lighting control signal from the microprocessor 6 to turn on the light. The display device 9 is turned on, the lighting state is confirmed, and a lighting confirmation signal is sent to the microprocessor 6. On the other hand, a lighting control signal is received from the microprocessor 6 to turn off the lighting display device 9 and the lighting state is turned off. After confirmation, a light-off confirmation signal is sent to the microprocessor 6.

The electric shock prevention circuit power supply 2 supplies an operating voltage to each component of the current cutoff circuit section 1.

Next, the operation of the electric shock prevention circuit having the above structure will be explained.

First, a case will be described in which a worker inserts his or her hand into the access area 101 for maintenance or the like while a current is flowing through the current path 102 (current cutoff switch 5 is closed).

In this case, the sensor light from the light projector 3 to the light receiver 4 is blocked by the operator's hand. The light receiver 4 notifies the microprocessor 6 that the sensor light has ceased. In the microprocessor 6, a cut-off control signal, e.g.
0'' level signal is sent to the switch opening/closing instruction circuit 7.The switch opening/closing instruction circuit 7 instructs the switch opening/closing actuator 8 to open the current cutoff switch 5.The switch opening/closing actuator 8 interrupts the current based on this instruction. The switch 5 is driven to open. After a certain period of time required for the drive has elapsed, the switch actuator 8 sends an opening confirmation signal to the switch opening/closing instruction circuit 7.
to the microprocessor 6 via the . Upon receiving this signal, the microprocessor 6 controls the lighting display execution circuit 10.
Sends a lighting control signal to. The lighting display execution circuit 10 lights the lighting indicator 9 in response to this signal to notify the operator that his or her hand is inserted into the access area 101. At this time, even if the hand touches the conductive portion 103, there is no risk of electric shock because the current is cut off. When a certain period of time has elapsed since the lighting indicator 9 was turned on, the lighting display execution circuit 10 sends a lighting confirmation signal to the microprocessor 6. The microprocessor 6 receives this signal and temporarily ends its operation.

Next, a case will be described in which the work in the access area 101 is completed and the worker's hand moves out of the area.

In this case, the shielding is released and the sensor light reaches the light receiver 4. The light receiver 4 informs the microprocessor 6 that the sensor light has returned. The microprocessor 6 sends a return control signal, for example, a signal of "1" level, to the switch opening/closing instruction circuit 7. The switch opening/closing instruction circuit 7 instructs the switch opening/closing actuator 8 to close the current cutoff switch 5. Based on this instruction, the switch opening/closing actuator 8 drives the current cutoff switch 5 to close it. As a result, the interrupted current in the current path 102 is restored. After a certain period of time required for driving has elapsed, the switch actuator 8 transmits a closing confirmation signal to the microprocessor 6 via the switch opening/closing instruction circuit 7. Upon receiving this signal, the microprocessor 6 transmits a lights-off control signal to the lighting display execution circuit 10. In response to this signal, the lighting display execution circuit 10 turns off the lighting indicator 9 to notify the operator that the operator is not in a dangerous area (access area 101). When a certain period of time has elapsed since the lighting indicator 9 was turned off, the lighting display execution circuit 10 transmits a lighting-off confirmation signal to the microprocessor 6. When microprocessor 6 receives this signal, it terminates its operation.

As described above, in this embodiment, the light emitter 3 and the light receiver 4 are placed around the conductive portion 103 of the access area 101.
are arranged opposite to each other to detect whether or not the sensor light is shielded, and when the sensor light is shielded, the current to the current path 102 is cut off by the current interrupting means, and when the sensor light is unshielded, the current returning means is used to interrupt the current to the current path 102. Since the current in the current path 102 is restored, the current is automatically cut off when the worker works in the access area 101, and the current is automatically restored after the work is completed. Therefore, electric shock to the worker can be reliably prevented, and the operation of the equipment, etc. can be promptly restored after the work is completed.

Furthermore, since the presence or absence of a worker is detected using the sensor light, there is no need to provide a protective shield as in the prior art, and work efficiency within the access area 101 is significantly improved.

Furthermore, since the lighting indicator 9 lights up when the current is cut off and turns off when the current is restored, electric shock can be more reliably prevented by the operator checking this display.

[0023]

As explained above, according to the present invention, there is provided an electric shock prevention circuit that does not limit the working area around the conductive part that conducts with the current path, and can reliably prevent electric shock during work. can be provided. Note that the present invention can also be applied to prevent electric shock in high voltage circuits.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an electric shock prevention circuit according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Current cutoff circuit part, 2...Power source for electric shock prevention circuit, 3...Current cutoff switch, 4...Light emitter, 5...Light receiver, 6...Microprocessor, 7...Switch opening/closing instruction circuit, 8...Switch opening/closing actuator, 9 ...Lighting indicator, 10...Lighting display execution circuit.

Claims (3)

[Claims] 1. A circuit for preventing electric shock in an access area in which a conductive part connected to a current path is placed in a part that can be touched by a worker, the floodlight emitting sensor light around the conductive part of the access area. and a light receiver, which is arranged to face the light emitter with a common optical axis at a certain interval and outputs different signals depending on when the sensor light from the light emitter is blocked and when the shielding is released, and the sensor light to the light receiver. The sensor is characterized by comprising a current interrupting means for interrupting the current flowing through the large current path when the sensor light is shielded, and a current returning means for restoring the current to the current path when the sensor light is unshielded. Electric shock prevention circuit. 2. The current interrupting means and the current restoring means receive an output signal from a current interrupting switch inserted in the current path and the light receiver as input signals, and when the input signal represents shielding of sensor light, a microprocessor that outputs a cutoff control signal and also outputs a return control signal when the input signal indicates unshielding of sensor light; and a microprocessor that receives the cutoff control signal and return control signal from the microprocessor and controls the current cutoff switch. 2. The switch control circuit according to claim 1, further comprising a switch opening/closing control circuit that opens and closes the switch, confirms the open and closed states, and sends an open confirmation signal and a closed confirmation signal to the microprocessor, respectively. Electric shock prevention circuit. 3. The electric shock prevention circuit according to claim 1 and claim 2, wherein the electric shock prevention circuit is provided near the access area;
a lighting indicator that selectively turns on and off; and a lighting indicator that receives lighting control signals and extinction control signals that are output when the microprocessor receives the opening confirmation signal and the closing confirmation signal, and controls the lighting indicator. An electric shock prevention circuit comprising a lighting display execution circuit that turns on and off the light, confirms the lighting state and the off state, and sends a lighting confirmation signal and a lights-off confirmation signal to a microprocessor, respectively.