JP2866792B2 - Ground detector for load equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground detecting device capable of detecting whether a ground wire of a load device is grounded to prevent an electric shock.

[0002]

2. Description of the Related Art Conventionally, for example, hot water in a bathtub is circulated,
Various load devices such as a circulation pump, a UV lamp for sterilizing and purifying, and the like are used in a sterilizing and purifying process, and further, a hot water circulation processing device for heating and the like. The outer parts of these load devices are grounded via a ground wire. And
When a leakage occurs, the leakage current flows into the ground through this ground wire, and the leakage prevention plug is detected and activated, thereby preventing the leakage.

[0003]

However, it is assumed that the ground wire of the load equipment is always grounded. If the ground wire is not grounded, it is possible to detect a leak from the load equipment. Lead to an electric shock accident . Heel
Power and ground terminals to prevent electrical shock.
Between which an optocoupler is provided as current detection means.
Proposal of a new sensor (for example, see Japanese Utility Model Application Laid-Open No. 3-3139)
Have been. However, conventional earth detectors are always grounded
In order to adopt the detection circuit configuration of the
Small current through the ground terminal of the load equipment to detect
Circuit. Therefore, the load equipment is not operating
Conversely, the detection circuit always connects the ground terminal to the
May cause electric shock accidents.
It is difficult to say that we are making every effort to prevent this.
Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and has as its object to determine whether or not a ground wire of a load device is grounded. An object of the present invention is to provide a grounding detection device that can detect and prevent an electric shock accident due to leakage of load equipment.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 is provided by connecting a power supply via a plug.
To detect the grounding status of the ground wire of the
Power supply circuit of a load device including the plug,
Contact between the ground wire connected to the ground terminal
A ground detection device, wherein the power supply circuit of the load device is connected to the connection circuit.
And a grounding test for the grounding wire.
To close the power supply circuit of the load equipment when necessary.
Opening and closing means forcibly connectable to the
Connected in series with the closing means and closing the opening / closing means
Time, the presence or absence of a ground fault current to the ground terminal is detected.
And a detecting means.

According to a second aspect of the present invention, there is provided the load according to the first aspect.
In the ground detection device of the device, the plug is
An earth leakage prevention plug that automatically shuts off the connection between the power supply and the load device.
A lug, a connector provided to control the opening and closing means.
When the grounding of the ground wire is detected, the
The ground fault current to the extent that the stop plug does not operate is
Flow through the ground terminal via the
The gist of the invention is to close the opening / closing means for a fixed short time .

[0007]

According to the first aspect of the present invention, the opening / closing means is a load machine.
The power supply circuit is closed when it is necessary to
Forcibly connect the path to the earth terminal. Directly with its opening and closing means
The detecting means connected in a row are closed when the opening / closing means is closed.
The presence or absence of a ground fault current to the ground terminal is detected. And ground fault
If current is detected, the grounding status of the ground wire is judged to be good.
It is. On the other hand, despite the closing of the switching
If no is detected, the grounding status of the grounding wire is judged to be defective
Is done. As long as the opening / closing means is open,
From the ground terminal to the ground terminal via the ground detection device.
The electrical connection is broken.

According to the second aspect of the present invention, the opening / closing means is controlled.
Controller that detects the grounding of the ground wire
To close the opening and closing means only for a short period of time.
From the power supply via the switching means and the detection means
The ground fault current flowing through the
Of the degree. Therefore, leakage prevention when detecting grounding
Malfunction of the plug is avoided before it occurs. In addition, leakage prevention plug
If the time is shorter than the shutdown time of the power
Test input of ground fault current higher than the lug operating current (test energization)
Grounding detection accuracy and reliability.
It is easy to increase.

[0009]

【Example】

(First Embodiment) Hereinafter, a first embodiment in which the present invention is embodied in a grounding detection device of a hot water circulation treatment device installed in a bathtub will be described with reference to FIG.

As shown in FIG. 1, a load device 2 is connected to a load power supply of AC 100 V via an earth leakage prevention plug 1. The load device 2 is grounded via a ground line 3. In the first embodiment, the load device 2 includes a circulating pump for circulating hot water in a bathtub, a heater for heating hot water, a UV lamp for sterilizing and purifying hot water, and the like.

The earth leakage prevention plug 1 shuts off a load power supply when a ground fault is detected. A series circuit of resistors 4 and 5 is connected between the output terminals of the leakage prevention plug 1. The leakage prevention plug 1, the resistor 4 and the resistor 5
The power supply circuit of the load device 2 is configured. A tilt switch 6 is connected between the connection point of the two resistors 4 and 5 and the ground terminal E. The tilt switch 6 is automatically turned on when the hot water circulation processing device is tilted at a predetermined angle, and the current from the load power supply is grounded. The load power is cut off by the earth leakage prevention plug 1.

A limiting resistor 8, a photocoupler 9 as detecting means, and a ground fault relay 20 as opening / closing means are connected in series between the connection point of the resistors 4 and 5 and the ground terminal E. The ground wire 3 is connected between the ground fault relay 20 and the ground terminal E. Light emitting diodes 10 and 11 are connected to the photocoupler 9 in parallel in opposite directions. When the grounding of the load device 2 is performed normally, the current from the load power supply is grounded by turning on the ground fault contact Xa, and the photocoupler 9 is turned on. At this time,
Since a current smaller than a normal ground fault current flows when the tilt switch 6 is turned on by the limiting resistor 8,
The leakage prevention plug 1 is not operated.

The collector terminal of the phototransistor 12 constituting the photocoupler 9 is connected to a DC 5 V
And the emitter terminal is connected to the substrate ground. In addition, a capacitor 14 is connected between the collector terminal and the emitter terminal of the phototransistor 12.

The collector terminal of the phototransistor 12 is connected to the controller 15. The controller 15 is connected to a notifying unit 16 such as a warning lamp or a buzzer provided on an operation panel of the hot water circulation processing device (not shown). When the controller 15 detects the High voltage (hereinafter, the High voltage is simply referred to as the H voltage, and the H voltage in this case is 5 V) at the time of detecting the ground, the ground line 3 of the load device 2 is grounded. It is determined that the load device 2 has not been
Is controlled to be inoperable. Conversely, the controller 15 is Lo
w voltage (hereinafter, Low voltage is simply referred to as L voltage,
The L voltage in this case is about 0V. ) Is detected, it is determined that the ground line 3 of the load device 2 is grounded.

A base terminal of a switching transistor (hereinafter, referred to as SW transistor) 18 is connected to the controller 15 via a resistor 17. One end of a resistor 22 is connected between the base terminal of the SW transistor 18 and the resistor 17, and the other end of the resistor 22 is connected to the substrate ground. The emitter terminal of the SW transistor 18 is connected to the substrate ground, and the collector terminal is connected to a 12 V DC power supply terminal via a drive coil 19. Then, when the load power supply is turned on, the controller 15 applies a predetermined voltage to the base terminal of the SW transistor 18,
The SW transistor 18 is turned on.

The ground fault relay 20 includes a drive coil 1.
9 and a ground fault contact Xa, and when the drive coil 19 is excited, the ground fault contact Xa is turned on. Both ends of the drive coil 19 are provided with protection diodes 2 for preventing back electromotive force generated when the drive coil 19 is turned off.
1 are connected in parallel.

In order to detect whether or not the ground wire 3 of the load device 2 is grounded to the ground terminal E, first, an operator operates an operation switch (not shown) to turn on the hot water circulation processing device. become. At the same time, the controller 15 applies a predetermined voltage to the base terminal of the SW transistor 18, turns on the SW transistor 18, and starts the ground detection.

The drive coil 19 is excited by the ON control of the SW transistor 18, and the ground fault contact Xa is turned on. That is, the ground fault relay 20 is turned on.
When the ground wire 3 of the load device 2 is connected to the ground terminal E, a minute current from the load power supply at which the leakage prevention plug does not operate flows to the ground terminal E. Then, the photocoupler 9 is turned on, and the voltage between both terminals of the capacitor 14 becomes the L voltage. As a result, the controller 15
Is supplied with the L voltage, and based on the L voltage, the controller 15 determines that the controller 15 is reliably grounded. afterwards,
The controller 15 turns off the SW transistor 18 and the ground fault relay 20 to start the normal operation of the load device 2. A series of operations in the case where the load device 2 is grounded by the above operation is terminated.

Next, a series of operations when the ground wire 3 of the load device 2 is not grounded to the ground terminal E will be described. Even if the ground fault relay 20 is turned on by the controller 15, no minute current flows from the load power supply to the ground terminal. At this time, the photocoupler 9 is in the OFF state, and the voltage between both terminals of the capacitor 14 becomes the H voltage of 5V. As a result, the H voltage is input to the controller 15 and this H voltage is input.
The controller 15 determines that the controller 15 is not grounded based on the voltage input.

Then, after the controller 15 controls the SW transistor 18 and the ground fault relay 20 to the OFF state, the controller 15 notifies the notifying unit 16 of the grounding fault state of the load device 2 and disables the operation of the load device 2. Subsequently, when a reset button (not shown) provided on the operation panel is operated by the operator, a reset signal is output to the controller 15. Then, the controller 15 repeats the above-described series of operations and disables the load device 2 until it determines that the load device 2 is properly grounded.

As described above, in the ground detection circuit of the first embodiment, if the ground wire 3 of the load device 2 is not grounded to the ground terminal E, the controller 15 displays a faulty ground state on the notification unit 16. In addition, the operation of the load device 2 can be disabled until the grounding state is confirmed. As a result, electric leakage by the load device 2 is reliably prevented.

(Second Embodiment) Next, a second embodiment of the present invention which is embodied as a grounding detection device and a power supply cutoff device for a load device in a hot water circulation treatment device installed in a bath tub is shown in FIGS. Explanation will be made according to 6.

As shown in FIG. 3, a load device 32 is connected to a load power supply of AC 100 V via an earth leakage prevention plug 31. The load device 32 is grounded via a ground line 33. In the second embodiment, the load device 32 includes a circulation pump for circulating hot water in the bathtub, a heater for heating the hot water, a UV lamp for sterilizing and purifying the hot water, and the like.

The earth leakage prevention plug 31 shuts off the load power supply when a ground fault is detected. A series circuit of resistors 34 and 35 is connected between the output terminals of the leakage prevention plug 31. Earth leakage prevention plug 31, resistor 34 and
The resistor 35 forms a power supply circuit of the load device 32. A tilt switch 36 is connected between the connection point of the two resistors 34 and 35 and the ground terminal E. The tilt switch 36 is automatically turned on when the hot water circulation processing device is tilted at a predetermined angle, and the current from the load power supply is grounded. The load power supply is turned off by the leakage prevention plug 31.

A connection point between the resistors 34 and 35 and a ground terminal E
Between the limiting resistor 56 and a semiconductor switch as an opening and closing means.
A first phototriac 52, a resistor 57, a photocoupler 38 as a detecting means, and a ground fault relay 37 are connected in series. Ground terminal E and ground fault relay 37
Is connected to the load device 32 via a ground wire 33. The light emitting diode 5 is provided in the photocoupler 38.
4, 55 are connected in parallel in opposite directions.

The collector terminal of a phototransistor 41 constituting the photocoupler 38 is connected to a D terminal via a resistor 42.
The power supply terminal of C5V is connected, and the emitter terminal is connected to the substrate ground. A capacitor 43 is provided between the collector terminal and the emitter terminal of the phototransistor 41.
Is connected.

The collector terminal of the phototransistor 41 is connected to the controller 44. Controller 44
Is connected to a display unit 45 such as a warning lamp provided on an operation panel of the hot water circulation processing device (not shown). When the controller 44 detects the H voltage (about 5 V) at the time of detecting the ground, the ground line 3 of the load device 32 is detected.
3 judges that it is not grounded, displays it on the display unit 45, and controls the load device 32 to be inoperable. Conversely, when detecting the L voltage (about 0 V), the controller 44 determines that the ground line 33 of the load device 32 is grounded. The controller 44 includes a timer (not shown).

The controller 44 receives a signal S via a resistor 46.
The base terminal of the W transistor 47 is connected. S
One end of a resistor 48 is connected between the base terminal of the W transistor 47 and the resistor 46, and the other end of the resistor 48 is connected to the substrate ground. The emitter terminal of the SW transistor 47 is connected to the substrate ground, and the collector terminal is connected to a 12 V DC power supply terminal via a drive coil 49. Then, when the ground fault detection is necessary, the controller 44 applies a predetermined voltage to the base terminal of the SW transistor 47, and turns on the SW transistor 47.

The ground fault relay 37 is connected to the drive coil 4.
9 and a ground-fault contact Xa1 which is a normally open contact. When the drive coil 49 is excited, the ground-fault contact Xa1 is turned on. A protection diode 51 for preventing back electromotive force generated when the drive coil 49 is turned off is connected in parallel to both terminals of the drive coil 49.

A second phototriac 53 connected in parallel with the first triac 52 is connected between the connection point of the resistors 34 and 35 and the photocoupler 38. The first and second photo triacs 52 and 53 are composed of triacs 52a and 53a and light emitting diodes 52b and 53, respectively.
b. Light emitting diodes 52b, 53
b is turned on by an operation signal from the controller 44. When the light emitting diodes 52b and 53b are turned on, the first and second phototriacs 52 and 53b are turned on.
Reference numeral 53 indicates an ON operation.

The light emitting diode 5 of the photocoupler 38
A limiting resistor 56, a triac 52a, and a resistor 57 are connected in series between the anode terminal of No. 4 and the connection point of the resistors 34, 35. On the other hand, a triac 53a is connected between the cathode terminal of the light emitting diode 54 of the photocoupler 38 and the connection point of the resistors 34 and 35.
A resistor 60 is connected in parallel between a connection point between the resistor 57 and the triac 52 a and a cathode terminal of the light emitting diode 54.

The light emitting diode 52b of the first photo triac 52 is connected to a 5V DC power supply terminal via a resistor 58, and is connected to the controller 44 in a series circuit with the resistor 58. On the other hand, the light emitting diode 53b of the second phototriac 53
The resistor 59 is connected to a power terminal of 5 V DC, and is connected to the controller 44 in a series circuit with the resistor 59.

Next, the operation of the ground detection device having the above-described configuration will be described with reference to the flowcharts of FIGS. FIG. 4 shows the operation of the entire hot water circulation processing device, and FIG. 5 shows the operation of ground detection by the ground detection device.

First, the operation of the entire hot water circulation processing apparatus will be described. As shown in FIG. 4, in a state where power is supplied to the hot water circulation device in step 1 (hereinafter, step is referred to as S), initial settings such as heater temperature settings are performed. In step S2, the power supply to the controller
The timer built in 4 starts time measurement. In S3, it is detected whether or not the ground wire 33 of the load device 32 is grounded to the ground terminal E.
If it is detected that is not grounded, the process proceeds to S5. The detection of the ground in S3 is called an earth check routine.

In S5, the controller 44 receives the detection signal and
Displays the display unit 45 to notify the user of the abnormality. At the same time, in S6, the controller 44 stops if the load devices 32 such as the heater, the sterilizing lamp, and the pump are operating.

In S4, if the controller 44 detects that the ground wire 33 of the load device 32 is grounded to the ground terminal E, the process proceeds to S7. When the user turns on the operation switch in S7, the operation proceeds to S8.
Then, the earth check routine is executed. If it is determined in S9 that the controller 44 is not grounded, the process proceeds to S5, and the above-described operations of S5 to S6 are repeated. On the other hand, in S9, when the controller 44 detects that the ground wire 33 of the load device 32 is grounded to the ground terminal E, the load device 32 is turned on in S10 and starts operating.

Subsequently, if 24 hours have elapsed since the timer of the controller 44 started measuring the time in S11, the process proceeds to S12, and if not, the process proceeds to S15 described later. At S12, an earth check routine is executed. Thereafter, in S13, when it is detected that the controller 44 is not grounded, the process proceeds to S5 and the above-described operations of S5 to S6 are repeated.

On the other hand, in S13, the controller 44
Detects that the ground wire 33 of the load device 32 is grounded to the ground terminal E, the controller 44 proceeds to S14.
Is reset to 0 hour, the time measurement is started again, and the process proceeds to S15.

At S15, the temperature of the circulating hot water is detected by a temperature sensor (not shown) connected to the controller 44.
The controller 44 controls the heating temperature of the heater in order to keep the temperature of the circulating hot water constant based on the detection signal from the temperature sensor. Accordingly, the operation of the load devices 32 such as the heater, the sterilizing lamp, and the pump in the hot water circulation processing device is controlled by the controller 44.

When the controller 44 detects in S16 that the operation of the load device 32 is abnormal in S15, the process proceeds to S17. In addition, as an abnormality of the operation of the load device 32, for example, an abnormal rise in the temperature of the heater, sterilization of the circulating hot water without the operation of the germicidal lamp, and an inability of the pump to run to make the circulating of the hot water impossible. There are cases. In S17, the controller 44 stops the load device 32 causing the abnormality, displays the display unit 45, and notifies the user that the load device 32 is abnormal,
This control routine ends.

In step S16, the controller 44 sets the load device 3
If it is detected that the operation state of No. 2 is normal, S18
If the operation switch of the load device 32 is in the ON state, the above-described operation after S11 is repeated. If the user operates an operation switch (not shown) in S18 and the operation switch of the load device 32 is turned off, the process proceeds to S18.
Go to step 19. Then, in S19, the load devices 32 such as the heater, the sterilizing lamp, and the pump are stopped. After that, the above-described operation after S7 is repeated.

Next, the earth check routine described in S3, S8 and S12 will be described in detail. As shown in FIG. 5, in S20, the drive coil 49 is excited by the ON control of the SW transistor 47, and the ground fault contact Xa
1 is input. That is, the ground fault relay 37 is turned on. Then, after the ground fault relay 37 is turned on in S21,
The controller 44 turns on the first phototriac 52 at a predetermined timing. Then, the process proceeds to S22 to S24, which is the primary determination.

In S22, when the ground wire 33 of the load device 32 is connected to the ground terminal E, the load power is supplied to the ground terminal E via the first triac 52, the photocoupler 38, the ground fault relay 37, and the like. A ground fault current flows from the load power supply. That is, as the first triac 52 is turned on, the photocoupler 38 is turned on, and the voltage between both terminals of the capacitor 43 becomes the L voltage. Based on this L voltage, the controller 44 determines that the ground wire 33 of the load device 32 is grounded to the ground terminal E, and proceeds to S23.

In S22, the ground wire 3 of the load device 32 is
3 is not connected to the ground terminal E, the photocoupler 38 is turned on even if the first triac 52 is turned on.
However, the voltage between both terminals of the capacitor 43 becomes the H voltage. Then, the H voltage is input to the controller 44. Based on the H voltage, the controller 44 determines that the ground wire 33 of the load device 32 is not connected to the ground terminal E, and proceeds to S24. In the primary determination, the controller 44 performs the voltage level determination in S22 at intervals of 1 ms.

If the controller 44 detects that the voltage between both terminals of the capacitor 43 has become the L voltage three times consecutively in S23, it is determined that the load device 32 is grounded, and the earth check routine ends. . On the other hand, if the controller 44 does not detect that the voltage between both terminals of the capacitor 43 becomes the L voltage three consecutive times in S23,
Move to.

In S24, it is determined whether or not the controller 44 has performed the voltage level determination of the H voltage or the L voltage between both terminals of the capacitor 43 a total of 16 times. If the controller 44 does not detect that the voltage between both terminals of the capacitor 43 has become the L voltage three consecutive times even after completing the voltage level determination of all 16 times, the primary determination is performed. And the process moves to S25.

In S25 to S27, the controller 44 performs a secondary determination in order to perform the voltage level determination described in the primary determination again. That is, S25
In step S22, when a ground fault current flows from the load power supply to the ground terminal E and the voltage between both terminals of the capacitor 43 becomes the L voltage, the ground wire 33 of the load device 32 is grounded to the ground terminal E in the same manner as in S22. Then, the process proceeds to S26. If the voltage between both terminals of the capacitor 43 becomes the H voltage in S25 and it is determined that the ground wire 33 of the load device 32 is not connected to the ground terminal E, the process proceeds to S27. Also Oite the Second determination primary determination and the controller 44 in the same manner as the voltage level determination of S25 1
Perform 16 times every ms.

In step S26, if the controller 44 detects that the voltage between both terminals of the capacitor 43 has become the L voltage three consecutive times in the same manner as in step S23, it is determined that the load device 32 is grounded. Then, the earth check routine ends. If the controller 44 does not detect that the voltage between both terminals of the capacitor 43 has become the L voltage three consecutive times in S26, the process proceeds to S27.

In S27, as in S24, it is determined whether or not the controller 44 has performed the voltage level determination between the two terminals of the capacitor 43 a total of 16 times. If the controller 44 does not detect that the voltage between both terminals of the capacitor 43 becomes the L voltage three times in a row even after completing all 16 voltage level determinations, the secondary determination is performed. And the process moves to S28. In step S28, an error flag is set, and the earth check routine ends.

As described above, in the ground detection circuit of the second embodiment, similarly to the first embodiment, if the ground wire 33 of the load device 32 is not grounded to the ground terminal E, the controller 44 displays the signal. The grounding failure state can be displayed on the unit 45, so that the electric leakage by the load equipment 2 is reliably prevented. At the same time, by using the first phototriac 52, unlike the contact portion of the mechanical contact, chattering does not occur and the switching function is not reduced when the ground is detected. And ground detection can be performed.

Also, by providing the second photo triac 53, if there is an abnormality in the load device 32, the controller 44 turns on the second triac 53 to force the current from the load power supply. Due to the ground fault, the power of the load device 32 is shut off by the leakage prevention plug 31. Therefore, the second triac 53
Since the load device 32 is stopped by the ON operation, the operation of the load device 32 can be stopped instantaneously. As a result, when abnormal heating of the heater or the like as the load device 32 occurs, the operation of the heater is reliably stopped by the second triac 53, so that there is no possibility of causing thermal damage to components around the heater.

It should be noted that the present invention is not limited to the above-described first and second embodiments, and may be appropriately changed as follows without departing from the spirit of the present invention. (1) For example, as shown in FIG. 2, the ground fault relay 20 shown in the first embodiment may be omitted, and a manual ground fault switch 27 may be provided as an opening / closing means instead. According to this configuration, when the manual ground fault switch 27 is turned on by the operation of the operator, the grounding state can be confirmed by turning on the display 26 using a light emitting diode or the like. In this case, the display 2
Reference numeral 6 plays a role of detecting means. Therefore, the first and second
The circuit structure can be simpler than the circuit shown in the embodiment , and the cost can be reduced.

(2) A current transformer (CT) may be used in place of the photocoupler 9 shown in the first embodiment to detect whether a ground fault has occurred. (3) The limiting resistor 8 shown in the first embodiment may be omitted. Then, when the controller 15 detects an abnormality of the heater by a thermistor or the like, the ground fault contact Xa may be turned on to activate the earth leakage prevention plug 1 and cut off the power. That is, when detecting an abnormality in the heater, the controller 15 increases the closing time of the ground fault contact Xa, and shortens the closing time of the ground fault contact Xa (several msec) when detecting grounding. Control so that a large current does not flow when the ground is detected.

(4) In the above-described second embodiment, the first and second phototriacs 52 and 53 are used as semiconductor switches.
SCR, GTO, etc. may be used.

(5) In the first and second embodiments,
Although the tilt switch 36 is a mechanical contact, it may be changed to a semiconductor switch such as a phototriac, a switching transistor, an SCR, or a GTO.

(6) In the second embodiment, the ground fault relay 37 may be omitted, and the power supply circuit of the load device 32 may be forcibly grounded to the ground terminal E using only the first phototriac 52.

[0057]

Effect of the Invention According to the invention of claim 1 (ground detector), detects whether the ground line of the load device is grounded, Ru can be prevented leakage of the load equipment. Special
In addition, this grounding detection device needs to detect the grounding of the grounding wire.
Only when the opening / closing means is closed,
Confirmation is possible, so the ground detection is performed unless necessary.
A ground fault current from the power supply through the device to the earth terminal
I can't get it. Therefore, the conventional earth detection device of the always grounding method
Unlike the ground contact detection device,
The load equipment casing, etc. in the ground fault condition is always in the power-on state.
Safety from the perspective of preventing electric shock without falling
Can be further improved.

According to the invention of claim 2 (ground detection device)
For example, the closing time of the opening / closing means when detecting the grounding of the grounding wire
Flows to the ground terminal via the opening / closing means and the detecting means.
Short enough for ground fault current not to activate the leakage prevention plug
It is. Therefore, if the ground exceeds the operating current of the leakage prevention plug,
When the short-circuit current is shorter than the shut-off operation time of the leakage prevention plug
It is possible to input the test only during the test
It is possible to improve the detection accuracy of the ground fault current by the
And thus the reliability of ground detection by the ground detection device
Can be improved. Also, when detecting grounding,
Malfunction of the antistatic plug can be avoided before it occurs.

[Brief description of the drawings]

FIG. 1 is a circuit diagram for detecting a ground according to a first embodiment of the present invention.

FIG. 2 shows another example of the first embodiment, and is a circuit diagram obtained by improving FIG. 1;

FIG. 3 is a circuit diagram for detecting ground in the second embodiment.

FIG. 4 is a flowchart showing the operation of the entire hot water circulation processing device when a ground contact is detected in the second embodiment.

FIG. 5 is a flowchart illustrating an operation of detecting a ground by a ground detection device according to a second embodiment.

[Explanation of Signs ] 1 ... Leakage prevention plug, 2,32 ... Load equipment, 3,33 ...
Ground wire, 4,5 ... resistance (1, 4 and 5 constitute power supply circuit
), 9, 38 ... photocoupler (detection means), 15 ...
Controller, 20: ground fault relay (opening / closing means), 26 ...
Display (detection means) 27 Manual ground fault switch (open / close
(Stage), 31 ... leakage prevention plug, 34, 35 ... resistance (3
1, 34 and 35 constitute a power supply circuit), 44.
Troller, 52 ... First Photo Triac (opening and closing hand
E) Ground terminal.

Claims (2)

(57) [Claims] 1. A negative power supply from a power supply via a plug.
In order to detect the grounding condition of the ground wire of
Connected to the power supply circuit of the
A ground detection device interposed between the ground line and the ground line.
Te, provided between the ground line and the power supply circuit of the load device
Closed when it is necessary to detect the grounding of the grounding wire.
To forcibly contact the power supply circuit of the load device to the ground terminal
And closing means to continue possible, while being the switching means connected in series, the switching means
Detecting means for detecting the presence or absence of a ground fault current to the ground terminal when the device is closed . 2. The power supply and the load device are connected to each other when a ground fault occurs.
Is a leakage prevention plug that automatically cuts off the connection of the controller, the controller provided to control the opening and closing means,
When the grounding of the grounding wire is detected, the leakage prevention plug is activated.
Ground fault current which does not move the switching means and detecting means.
Through the ground terminal for a predetermined short time
2. The grounding detecting device for a load device according to claim 1, wherein the opening / closing means is closed .