JPS5927271A - Earth connection detector - Google Patents

Abstract

PURPOSE:To enable the detection of disconnection of a earth wire connected to a power source plug by arranging a power source plug having a power source connection terminal and an earth terminal, a power source cable having the earth wire and a detection wire and a earth connection detecting circuit. CONSTITUTION:When a power source plug 5 is plugged into a plug socket, a power source connection terminal 7 is connected to a commercial power source and the power is supplied to a transformer 13 through power source wires 8 and 8 and then, to an earth connection detecting circuit 11. The power supplied drives a relay 12 to close a relay contact 3, which allows the supply of power to an electric circuit 2 to operate an electric equipment 1. On the other hand, in case an earth wire 10 is disconnected, current fails to flow to a detection wire 9 and no power is supplied to the detection circuit 11. Thus, the closure of the relay contact 3 won't be done and no power is supplied to the electric circuit 2 disabling the electric equipment 1. Thus, disconnection of the earth wire 10 connected to the plug 5 can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a grounding connection detection device for a plug having a grounding terminal.

To avoid the risk of electric shock, electrical equipment with internal electrical parts must be grounded to the exterior of the equipment (51C). Particularly when the equipment is used for medical purposes, the grounding wire must be reliably connected to protect patients, who have low resistance to electric shock, from the risk of electric shock.

Therefore, in the past, for example, Utility Model Application No. 50-15337
As disclosed in the No. 1, a detection electrode is provided on a grounding clip for connecting a grounding wire to an indoor grounding terminal, and a detection wire is used to connect the connection detection current supply means provided inside the maintenance equipment and the detection electrode. , open the above clip and insert the grounding terminal.This will connect the sensing electrode, grounding terminal, grounding electrode,
Flow the connection detection current in the order of the grounding wire, and calculate the magnitude of the current K
The connection status of the Yotsumata grounding wire was monitored, and if the current was below a certain value, it was detected as a connection failure and a display or warning was issued.

In addition, plugs with a grounding terminal, such as two-pole grounding plugs, have a grounding terminal on one body, so you can connect the grounding wire to the grounding terminal by inserting it into the connector. . This ground wire is attached to the power cable. Therefore, when the power plug is inserted into the outlet, the connection is automatically made, but if the ground wire in the power cable is broken, the break cannot be detected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a grounding connection detection device capable of detecting disconnection of a grounding wire connected to a plug having a grounding terminal.

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 1 is a configuration diagram of the ground connection detection device 6. As shown in FIG.

An electric circuit 2 is provided inside the electric device l. A power source 4 is connected to the electric circuit 2 via a relay contact 3, and a power plug 5 is connected to the other end of the power cable 4. This power plug 5 is a grounded bipolar plug having a grounding terminal 6 and power supply connection terminals 7, 7, and the power cable 4 has four cores. Power connection terminal 7 of plug 5
．． A power line 8.8 having two out of four cores of the power cable 4 is connected to the power line 7, and the power line 8.8 is connected to the relay contact 3. In addition, the remaining 2 cores of power source group 4 are plug 5
A detection wire 9 and a grounding wire 10 are connected to the grounding terminal 6 of the sensor.

Furthermore, a ground connection detection circuit 11 is provided inside the electrical device 1, and this detection circuit 11 is connected to the relay contact 3 via a relay 12. This detection circuit 11 is connected to the power supply line 8.8 via the transformer 13 and is supplied with "'C power. Also, the detection line 9 and the grounding line 10 connected to the grounding terminal 6 are connected to the detection circuit 11. has been done.

FIG. 2 is a diagram showing the wiring state inside the power plug 5,
A power supply is connected to the power supply connection terminal 7.7. The grounding terminal 6 is slightly longer than the power supply connection terminal 7.7, and two connectors 14.14 are attached inside the plug 5. The detection wire 9 and the grounding wire 10 are connected to this connector 14.14. 14
1C are connected to each other.

The ground connection detection circuit 11 connected to the secondary side of the transformer 130 is shown in Figure WJ3 - A rectifier 20 is connected to the secondary side of the transformer 13, and a current detection resistor is connected to the output terminal of the rectifier 20. 21. Detection line 9. Connector 14, grounding terminal 6. The grounding wires 10 are connected in series, and the grounding wires 10
is connected to external device a of electrical equipment l. A smoothing capacitor 22 is connected between output terminals of the rectifier 20.

In addition, 11I, the resistance at both ends of the current detection resistor 21 increases by 1↑J device 2
3 is connected, and the output of the amplifier 23 is connected to the drive circuit 24.
Activates relay 12 via.

In the above-described configuration, when the power plug 5 is inserted into an outlet (not shown), the power connection terminal 7.7 is connected to the commercial power supply, and the power supply is connected to the transformer 131 via the power line 8.8.
The C is then supplied to the detection circuit 11. The supplied power is rectified by a rectifier 20, and a current detection resistor 21,
Detection #i! 9, connector 14, grounding terminal 6, grounding wire 10
A current flows through the current detection resistor 210, and a voltage is generated across the current detection resistor 210. This voltage is amplified by the amplifier 23 and then drives the "C" relay 12 through the relay drive circuit 24'Ik to close the relay contact 3. As a result, power is supplied to the electric circuit 2 and the electrical equipment Enables the first operation.

On the other hand, if the grounding wire 10 is disconnected, no current flows through the detection line 9, and no voltage is generated across the current detection resistor. Therefore, the relay contact 3 is not closed, the electric circuit 2 cannot receive power, and the electric device 10 cannot be used.

As mentioned above, if the grounding wire 10 is disconnected,
Since no power is supplied to electric circuit 2, 1! The danger of being attacked can be effectively prevented.

Incidentally, in the above-described embodiment, the input relay spot 3 of the electric circuit 2 is used, but it is not limited to the relay spot 3; however, it is also possible to use a semiconductor switch such as a xyristor.

In addition to the switching of the relay 12, a warning/display may be performed using a lamp, a gas sensor, etc. based on the signal of disconnection detection.

[Brief explanation of the drawing]

Fig. 1 shows the configuration of one embodiment of the present invention +11 connection detection device M), Fig. 2 shows the inside of the power plug part 2, Fig. 3
The figure is an electrical circuit diagram. 1...Electrical equipment, 4...! &, #, cable, 6...
- Grounding terminal, 7... Power supply connection terminal, 8... Power supply line, 9... Detection line, 10... Grounding wire, 11... Grounding connection detection circuit.

Claims (1)

[Claims] A power supply having a power supply plug having a power supply connection terminal and a grounding terminal, a power supply line that is connected to the power supply connection terminal +K and supplies power to the electrical equipment, and a detection wire and a grounding wire that are respectively connected to the above-mentioned grounding terminal. Cable, the above detection wire, ground wire and l
1. A grounding connection detection device comprising: a grounding connection detection circuit that detects a current by flowing a connection detection current of a grounding line.