JPH0783976A - Ground detector for load apparatus - Google Patents

Abstract

PURPOSE:To prevent ground fault of a load apparatus by whether the apparatus is properly grounded or not. CONSTITUTION:A ground relay 20 which can ground a power source to a ground terminal E and a photocoupler 9 for detecting whether a load apparatus 2 is grounded or not are provided on a ground line 3 of the apparatus 2 such as a circulation pump, etc., to be used, for example, for a warm water circulating processor for circulating and heating warm water in a bathtub. With this structure, before the apparatus 2 is started, a power source circuit of the apparatus 2 is forcibly grounded to the terminal E by the relay 20. In this case, when the power source circuit of the apparatus 2 is effectively grounded, the apparatus can be operated by ON of the photocoupler 9. On the contrary, when the power source circuit of the apparatus 2 is not grounded, the photocoupler 9 becomes OFF. In this case, a controller 15 informs that the line 3 of the apparatus 2 is not grounded to an informing unit 16 via a lamp, a buzzer, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground detection device capable of detecting whether or not the ground wire of a load device is grounded to prevent electric shock.

[0002]

2. Description of the Related Art Conventionally, for example, hot water in a bath is circulated,
Various load devices such as a circulation pump, a UV lamp for sterilizing and purifying, and a heater are used for a sterilizing and purifying treatment, a hot water circulating treatment device for heating, and the like. The outer parts of these load devices are grounded via a ground wire. And
When a leakage occurs, a leakage current flows into the ground through this ground wire, and the leakage prevention plug detects and operates to prevent leakage.

[0003]

However, it is premised that the ground wire of the load device is always grounded, but if it is not grounded, it is possible to detect a leak from the load device. It may lead to electric shock.

The present invention has been made in order to solve the problem existing in the above-mentioned conventional technique, and its purpose is to determine whether or not the ground wire of the load device is grounded. An object of the present invention is to provide a ground detection device that can detect and prevent an electric shock accident due to a leakage of load equipment.

[0005]

In order to solve the above problems, the invention according to claim 1 is connected to a ground wire of a load device, and the power supply circuit of the load device is forcibly grounded. The gist of the present invention is to include an opening / closing means capable of being closed and a detection means for detecting whether or not a ground fault has occurred by the operation of the opening / closing means.

According to a second aspect of the invention, the gist is that the opening / closing means is a semiconductor switch.

[0007]

According to the present invention having the above-described structure, the power supply circuit of the load device is forcibly grounded to the ground terminal by the operation of the opening / closing means before the load device is activated. At this time, the detection means detects whether or not the power supply circuit of the load device is reliably grounded.

According to the second aspect of the invention, the power supply circuit of the load device is grounded to the ground terminal by the semiconductor switch, but the semiconductor switch operates reliably and instantaneously to detect the ground. .

[0009]

【Example】

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

As shown in FIG. 1, a load device 2 is connected to an AC100V load power source via a leakage prevention plug 1. The load device 2 is grounded via a ground wire 3. In the first embodiment, the load device 2 includes a circulation pump that circulates the hot water in the bath, a heater that heats the hot water, a UV lamp that sterilizes and purifies the hot water, and the like.

The earth leakage prevention plug 1 shuts off the load power source when a ground fault is detected. A series circuit of resistors 4 and 5 is connected in parallel between the output terminals of the leakage prevention plug 1. A tilt switch 6 is connected between the connection point of the resistors 4 and 5 and the ground terminal E, and is automatically turned on when the hot water circulation processing device is tilted at a predetermined angle, and the current from the load power source is ground-faulted. Turn off the load power supply with the leakage prevention plug 1.

Further, a limiting resistor 8, a photocoupler 9 as a detecting means and a ground fault relay 20 as an 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 in parallel to the photocoupler 9 in opposite directions. When the load device 2 is grounded 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 the normal ground fault current, such as when the tilt switch 6 is turned on, flows due to the limiting resistor 8,
The leakage prevention plug 1 is designed not to operate.

The collector terminal of the phototransistor 12 which constitutes the photocoupler 9 is DC 5V via the resistor 13.
Is connected to the power supply terminal and the emitter terminal is connected to the substrate ground. 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 the operation panel of the hot water circulation processing device (not shown). When the controller 15 detects a high voltage (hereinafter, the high voltage is simply referred to as an H voltage, and the H voltage in this case is 5 V) at the time of detecting the ground, the ground wire 3 of the load device 2 is grounded. If the load device 2
Control to be inoperable. On the contrary, 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 wire 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 the 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 the DC12V power source terminal via the 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.

Further, the ground fault relay 20 includes the drive coil 1
9 and the ground fault contact Xa, and the ground fault contact Xa is turned on by the excitation of the drive coil 19. A protection diode 2 for preventing a back electromotive force generated when the drive coil 19 is turned off is provided at both terminals of the drive coil 19.
1 are connected in parallel.

To detect whether or not the ground wire 3 of the load device 2 is grounded to the ground terminal E, 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 to turn on the SW transistor 18 to start ground detection.

The ON control of the SW transistor 18 excites the drive coil 19 and turns on the ground contact Xa. That is, the ground fault relay 20 is turned on.
Then, when the ground wire 3 of the load device 2 is connected to the ground terminal E, a minute current from which the leakage prevention plug does not operate flows from the load power supply 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 inputted with L voltage, and it is judged that the controller 15 is surely grounded based on this L voltage. afterwards,
The controller 15 turns off the SW transistor 18 and the ground fault relay 20, and starts the normal operation of the load device 2. With the above operation, a series of operations when the load device 2 is grounded is completed.

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, a minute current does not flow from the load power source 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
Based on the input voltage, the controller 15 determines that it is not grounded.

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

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

(Second Embodiment) Next, a second embodiment of the second embodiment embodied in a grounding detection device for a load device and a power interruption device in a hot water circulation processing device installed in a bathtub according to the second embodiment will be described with reference to FIGS. 6 will be described.

As shown in FIG. 3, a load device 32 is connected to an AC100V load power source via a leakage prevention plug 31. The load device 32 is grounded via a ground wire 33. In the second embodiment, the load device 32 includes a circulation pump for circulating the hot water in the bath, 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 cuts off the load power source when a ground fault is detected. A series circuit of a resistor 34 and a resistor 35 is connected in parallel between the output terminals of the leakage prevention plug 31. A tilt switch 36 is connected between the connection point of the resistors 34 and 35 and the ground terminal E, and is automatically turned on when the hot water circulation processing device is tilted at a predetermined angle, and the current from the load power source is ground-faulted. The load power supply is cut off by the leakage prevention plug 31.

The connection point of both resistors 34 and 35 and the ground terminal E
A limiting resistor 56, a first phototriac 52 as a semiconductor switch, a resistor 57, a photocoupler 38 as a detecting means, and a ground fault relay 37 are connected in series between them. The load device 32 is connected between the ground terminal E and the ground fault relay 37 via a ground wire 33. Light emitting diodes 54 and 55 are connected in parallel to the photocoupler 38 in opposite directions.

The collector terminal of the phototransistor 41 which constitutes the photocoupler 38 is connected to D via a resistor 42.
It is connected to the power supply terminal of C5V and the emitter terminal is connected to the substrate ground. Further, a capacitor 43 is provided between the collector terminal and the emitter terminal of the phototransistor 41.
Are connected.

The collector terminal of the phototransistor 41 is connected to the controller 44. Controller 44
A display unit 45 such as a warning lamp provided on an operation panel of a hot water circulation processing device (not shown) is connected to the. When the controller 44 detects the H voltage (about 5 V) at the time of detecting the ground, the ground wire 3 of the load device 32 is detected.
No. 3 determines that it is not grounded, displays it on the display unit 45, and controls the load device 32 to be inoperable. On the contrary, when the controller 44 detects the L voltage (about 0 V), it determines that the ground wire 33 of the load device 32 is grounded. The controller 44 has a timer (not shown).

The controller 44 is connected to 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 the DC12V power supply terminal via the drive coil 49. Then, when the ground fault detection is required, the controller 44 applies a predetermined voltage to the base terminal of the SW transistor 47 to turn the SW transistor 47 on.

Further, the ground fault relay 37 includes the drive coil 4
9 and a ground fault contact Xa1 which is a normally open contact, and the ground fault contact Xa1 is turned on by the excitation of the drive coil 49. A protection diode 51 for preventing a counter 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 phototriacs 52, 53 are triacs 52a, 53a and light emitting diodes 52b, 53.
b and. Light emitting diodes 52b and 53
b is turned on by an operation signal from the controller 44. Then, by turning on the light emitting diodes 52b and 53b, the first and second phototriacs 52,
53 is adapted to be turned on.

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 and 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 the connection point of the resistor 57 and the triac 52a and the cathode terminal of the light emitting diode 54.

The light emitting diode 52b of the first phototriac 52 is connected to a DC5V 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 is
It is connected to a power supply terminal of DC 5V via a resistor 59 and is connected to the controller 44 in a series circuit with the resistor 59.

Next, the operation of the ground detection device constructed as described above will be described with reference to the flow charts of FIGS. 4 and 5. 4 shows the operation of the entire hot water circulation processing device, and FIG. 5 shows the operation of ground contact detection by the ground contact detection device.

First, the operation of the entire hot water circulation processing device will be described. As shown in FIG. 4, initial setting such as heater temperature setting is performed in a state where power is supplied to the hot water circulation device in step 1 (hereinafter, step is referred to as S). In step S2, the controller 4 is supplied with power to the controller 44.
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, and in S4, the controller 44
When it is detected that is not grounded, the process proceeds to S5. The ground detection in S3 is called a ground check routine.

The controller 44 receives the detection signal in S5.
Displays the display unit 45 to inform the user of the abnormality. At the same time, in S6, the controller 44 stops if the load device 32 such as the heater, the sterilization lamp, and the pump is in operation.

When the controller 44 detects in S4 that the ground wire 33 of the load device 32 is grounded to the ground terminal E, the process proceeds to S7. When the operation switch is turned on by the user in S7, S8 is accompanied with it.
Then, the earth check routine is executed. When it is detected 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, when the controller 44 detects in S9 that the ground wire 33 of the load device 32 is grounded to the ground terminal E, the load device 32 is turned on and operation is started in S10.

Subsequently, in S11, if 24 hours have elapsed since the timer of the controller 44 started time measurement, the process proceeds to S12, and if 24 hours have not elapsed, the process proceeds to S15 described later. In S12, the earth check routine is executed. After that, when it is detected in S13 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 in S14.
The timer is reset to 0 hour, the time measurement is started again, and the process proceeds to S15.

In 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 so as to keep the temperature of the circulating hot water constant based on the detection signal from the temperature sensor. Therefore, the load device 32 such as the heater, the sterilization lamp, and the pump in the hot water circulation processing device is operation-controlled by the controller 44.

Then, in S16, when the controller 44 detects an abnormal operation of the load device 32 in S15, the process proceeds to S17. It should be noted that, as an abnormal operation of the load device 32, for example, the heater has an abnormally high temperature, the sterilization lamp does not operate, and the circulating hot water cannot be sterilized, or the pump idles and the hot water cannot circulate. There are cases, etc. In S17, the controller 44 stops the load device 32 causing the abnormality, displays the display unit 45, and informs the user that the load device 32 is abnormal,
This control routine ends.

At S16, the controller 44 causes the load device 3
When the operating state of No. 2 is detected to be normal, S18
If the operation switch of the load device 32 is in the ON state, the above-described operations of S11 and subsequent steps are repeated. Further, if the operation switch (not shown) is operated by the user in S18 and the operation switch of the load device 32 is turned off, S
Go to 19 onwards. Then, in S19, the load devices 32 such as the heater, the sterilization lamp, and the pump are stopped. After that, the operations after S7 described above are repeated.

Next, the earth check routine described in S3, S8 and S12 will be described in detail. As shown in FIG. 5, the drive coil 49 is excited by the ON control of the SW transistor 47 in S20, and the ground fault contact Xa is generated.
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. After that, the first judgment is made. The process proceeds to S22 to S24.

In S22, when the ground wire 33 of the load device 32 is connected to the ground terminal E, the load power supply is connected to the ground terminal E through 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.

Further, in S22, the ground wire 3 of the load device 32 is
When 3 is not connected to the ground terminal E, the photo coupler 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 this 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 first determination, the controller 44 performs the voltage level determination of S22 at 1 ms intervals.

When the controller 44 detects that the voltage between both terminals of the capacitor 43 becomes L voltage three times in succession in S23, it is determined that the load device 32 is grounded, and the earth check routine is ended. . If the controller 44 does not detect that the voltage between both terminals of the capacitor 43 becomes the L voltage for three consecutive times in S23, S24 is performed.
Move to.

In S24, it is determined whether or not the controller 44 has performed the voltage level determination 16 times whether the voltage is the H voltage or the L voltage between both terminals of the capacitor 43. 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 the voltage level determination is completed 16 times, the primary determination is made. Is completed and the process proceeds to S25.

In order to re-execute the voltage level determination described in the primary determination in S25 to S27, the secondary determination is further performed by the controller 44. That is, S2
5, in the same manner as in S22, if a ground fault current flows from the load power source 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 determined to be grounded to the ground terminal E, and the process proceeds to S26. When the voltage between both terminals of the capacitor 43 becomes 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. In the second determination, the controller 44 determines the voltage level in S25 to be 1 as in the first determination.
16 times every ms.

If the controller 44 detects that the voltage between both terminals of the capacitor 43 becomes the L voltage for three consecutive times in S26 as in S23, it is determined that the load device 32 is grounded. , Terminate the earth check routine. When the controller 44 does not detect that the voltage between both terminals of the capacitor 43 becomes the L voltage three times in succession in S26, the process proceeds to S27.

In S27, similarly to S24, it is determined whether or not the controller 44 has performed the voltage level determination between both terminals of the capacitor 43 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 the voltage level determination is completed 16 times, the second determination is made. Is completed and the process proceeds to S28. In S28, the error flag is set and the earth check routine ends.

Thus, in the ground detection circuit of the second embodiment, as in 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. A poor grounding state can be displayed on the portion 45, and electric leakage due to the load device 2 can be reliably prevented. At the same time, by using the first phototriac 52, when detecting grounding, unlike the contact portion of the mechanical contact, chattering does not occur and the switching function is not degraded, so a more reliable and instantaneous switching operation is possible. Then, the ground can be detected.

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

The present invention is not limited to the first and second embodiments described above, and may be modified as follows within the scope of the spirit of the present invention. (1) For example, as shown in FIG. 2, the ground fault relay 20 shown in the first embodiment or another example may be omitted and a manual ground fault switch 27 may be provided instead. According to this configuration,
When the manual ground fault switch 27 is turned on by the operation of the operator, the ground detection can be confirmed by lighting the indicator 26 such as a light emitting diode. Therefore, the circuit structure can be made simpler than the circuit shown in the above-described embodiment or another example, 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 or not 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 operate the leakage prevention plug 1 to cut off the power supply. That is, the controller 15 lengthens the closing time of the ground fault contact Xa when detecting the abnormality of the heater, and shortens the closing time of the ground fault contact Xa (several msec) when detecting the ground contact. May be controlled so that a large current does not flow at the time of ground detection.

(4) In the above second embodiment, the semiconductor switch uses the first and second phototriacs 52 and 53, but in addition to this, switching transistors,
You may use SCR, GTO, etc.

(5) In the above first and second embodiments,
Although the tilt switch 36 is a mechanical contact, it may be replaced with 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 only by the first phototriac 52.

[0057]

As described above in detail, according to the first aspect of the present invention, it is possible to detect whether or not the ground wire of the load device is grounded and prevent leakage of the load device in advance. It has an excellent effect that it can be done.

According to the second aspect of the invention, the power supply circuit of the load device is grounded to the ground terminal by the semiconductor switch. Therefore, it is possible to detect whether or not the ground wire of the load device is grounded, and to prevent the electric shock accident due to the electric leakage of the load device in advance.

[Brief description of drawings]

FIG. 1 is a circuit diagram for detecting a ground in a first embodiment embodying the present invention.

FIG. 2 is a circuit diagram showing another example of the first embodiment, which is an improved version of FIG.

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

FIG. 4 is a flow chart 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 flow chart showing an operation of ground contact detection by the ground contact detector according to the second embodiment.

[Explanation of symbols]

2, 32 ... Load device, 3, 33 ... Ground wire, 9, 38 ... Photocoupler (detection means), 20 ... Ground fault relay (opening / closing means), E ... Ground terminal, 52 ... First phototriac (semiconductor switch)

Claims (2)

[Claims] 1. An opening / closing means which is connected to a ground wire of a load device and forcibly grounds a power supply circuit of the load device to a ground terminal, and detects whether or not a ground fault has occurred by the operation of the opening / closing means. And a grounding detection device for a load device. 2. The ground detection device for a load device according to claim 1, wherein the opening / closing means is a semiconductor switch.