JPH04215216A - Device for detecting contact welding of switch - Google Patents

Abstract

PURPOSE:To detect contact welding of each phase of a multiphase alternating current switch with one device for detecting contact welding. CONSTITUTION:The signal, which is obtained by reversing the exciting signal of an electromagnetic coil 2 with an inverter 5, and the switching signal of a main contact point 4 are input to an AND circuit 6, and welding of the main contact point 4 is monitored on the basis of the signal output P at the time when the switching signal is changed to H even if the driving signal is L. At this stage, an auxiliary (a) contact point 7a to be coupled with the main contact point 4 is provided, and the switching signal of the main contact point 4 is output from this auxiliary (a) contact point 7a, and contact welding of all phases is thereby detected by one circuit for detecting contact welding.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact welding detection device for a switch such as an electromagnetic contactor or a molded circuit breaker, which detects when a main contact is welded.

0002

[Prior Art] If the main contacts of electromagnetic contactors for controlling motor operation and circuit breakers for protecting wiring are welded, the current cannot be interrupted unless the upper circuit breaker is used, which is extremely dangerous. It becomes a state. Therefore, in order to quickly detect such a situation, a contact welding detection device as shown in FIG. 12 has been conventionally used. In the figure, reference numeral 2 denotes an electromagnetic coil of an electromagnet in an electromagnetic contactor, which is connected to a control power source Vcc via an input switch 1. Further, 4 is a main contact of an electromagnetic contactor which is driven by the electromagnetic coil 2 to open and close, and is inserted between the load 3 and the main power source Vb. Contact welding detection device is inverter 5 and AN
The input end of the inverter 5 is connected between the input switch 1 and the electromagnetic coil 2, and the output end is an AN
It is connected to one input end of the D circuit 6. Also, AN
The other input end of the D circuit 6 is connected between the load 3 and the main contact 4. The output of the AND circuit 6 becomes a detection signal P0 warning of contact welding, and is sent to a processing circuit (not shown).

[0003] When the input switch 1 is turned on, the electromagnetic coil 2 is excited, the main contact 4 is turned on, and the load 3 is energized. At this time, the coil voltage of the electromagnetic coil 2 becomes a high level (H), but is inverted by the inverter 5 to become a low level (L) and is input to one input terminal of the AND circuit 6. Further, the voltage of the load 3 is input as H to the other input terminal of the AND circuit 6. As a result, the detection signal P0 of the AND circuit 6 becomes an L normal signal.

When the input switch 1 is turned off from this state, the excitation of the electromagnetic coil 2 is released, the main contact 4 is turned off, and the load 3 is stopped. At this time, the coil voltage of the electromagnetic coil 2 changes to L, and the inverted output of the inverter 5 inputted to one input terminal of the AND circuit 6 changes to H, but the voltage of the load 3 inputted to the other input terminal To change to L, AND
The detection signal P0 of the circuit 6 becomes L, indicating no abnormality.

If welding occurs at the main contact 4, even if the input switch 1 is turned off and the electromagnetic coil 2 is de-energized, the main contact 4 remains on and the load 3 continues to be energized. Then, the H of the coil voltage inversion signal and the H of the load voltage are input to the AND circuit 6, and the detection signal P
0 changes to H and warns that welding has occurred. As a result, protection processing for the load 3 by displaying an alarm and shutting off the upper-level circuit breaker is performed.

[0006]

Conventionally, in such a contact welding detection device, the opening/closing signal of the main contact 4 is extracted from the main circuit in which it is inserted, as shown in FIG. Therefore, if the load is a multiphase alternating current, a contact welding detection device must be provided for each phase. Furthermore, if these devices are combined into one device, the device will become larger and the wiring will become complicated. This invention provides a contact welding detection device for a switch, which is capable of detecting contact welding of each phase even in a multiphase AC switch using a conventional one-phase contact welding detection device, thereby reducing the cost and downsizing of the device. The purpose is to provide the following. Furthermore, when two electromagnetic contactors are used to operate a motor in forward and reverse directions, contact welding has conventionally been detected for each switch. Therefore, an object of the present invention is to provide a switch contact welding detection device that can detect contact welding of a plurality of switches at once in such a case.

[0007]

[Means for Solving the Problems] Even in multiphase AC electromagnetic contactors and molded circuit breakers, the main contacts of each phase are generally driven to open and close integrally. This invention focuses on this point, and provides an auxiliary contact that interlocks with a main contact that opens and closes a load such as an electromagnetic contactor, and extracts the switching signal of the main contact from this auxiliary contact.

The auxiliary contacts are an a contact (normally open contact) and a b contact (
Either normally closed contact (normally closed contact) can be used, but if an a contact is used, welding of the main contact is detected by the logical product of the opening/closing signal of the auxiliary a contact and a signal obtained by inverting the drive signal of the electromagnetic coil. Further, when the auxiliary contact is a B contact, welding of the main contact is detected by the AND of a signal obtained by inverting the opening/closing signal of the auxiliary B contact and a signal obtained by inverting the drive signal of the electromagnetic coil.

[0009] When a motor is operated in forward and reverse directions using two electromagnetic contactors, the main contacts of the two electromagnetic contactors are not closed at the same time. In this way, the switching signals of the main contacts of multiple switches that open and close the same load but do not operate simultaneously are combined together with the drive signals of the electromagnets of each switch that opens and closes each of the main contacts. There is no problem even if it is input to one contact welding detection device. In that case, if you provide an auxiliary b contact that interlocks with the main contact of each switch, input the switching signal of this auxiliary b contact in series, and input the drive signal of the electromagnet of each switch in parallel, the electromagnet drive signal By simply adding one input terminal, one contact welding detection device can be used for multiple switches.

[0010] The molded case circuit breaker is also provided with an auxiliary contact that interlocks with the main contact, and the opening/closing signal of the main contact taken out from the auxiliary contact and the electromagnet drive signal of the tripping device that opens the main contact are combined. Welding of the main contacts is detected by logical product. If the above tripping device is an undervoltage tripping device, the main contact opens when the electromagnet is de-energized, but in the case of a voltage tripping device, the main contact opens when the electromagnet is driven, so the logical product is The levels of the signals taken are opposite to each other. The auxiliary contact may be either an a contact or a b contact.

[0011]

[Operation] For example, in the case of a three-phase AC electromagnetic contactor or molded circuit breaker, the three main contacts are held by an integral contact support and open and close at the same time. Since the entire contact is restricted to the ON state, one auxiliary contact that is opened and closed in conjunction with the main contact by the contact support can represent the open/close state of the main contacts of each phase and the presence or absence of welding. Therefore, welding of the main contacts of each phase of the multiphase AC switch can be detected by logical product of the switching signal from the auxiliary contact and the drive signal of the electromagnet that opens and closes the main contact.

In electromagnetic contactors and undervoltage trip circuit breakers, if the main contact is ON even though the electromagnet drive signal is L, welding has occurred, so the drive signal is reversed. and input it to the AND circuit. On the contrary,
In a voltage trip circuit breaker, if the main contact is ON even though the electromagnet drive signal is H, welding has occurred, so the drive signal is input to the AND circuit as is. On the other hand, if the auxiliary contact is a contact, the open/close signal from the auxiliary contact is input directly to the AND circuit, and if the auxiliary contact is a contact b
If it is a contact, it is inverted and input to the AND circuit.

[0013] When switching the same load using multiple switches that do not operate simultaneously, such as when operating a motor in forward and reverse directions using two electromagnetic contactors, a contact welding detection device is provided for each switch. By combining the signals from each switch, a single contact welding detection device can handle the problem. At that time, the drive signal of the electromagnet of each switch is input in parallel to a common contact welding detection device, while the auxiliary contact that is linked to the main contact of each switch is a B contact, and the opening/closing signal from this auxiliary B contact is Inputting them in series simplifies the configuration.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. Note that the same reference numerals are used for parts corresponding to those in the conventional example. Example 1 First, FIG. 1 shows a first example. In the figure, a motor load 3 is connected to a three-phase AC power source of R, S, and T via a main contact 4 of an electromagnetic contactor inserted in each phase. An electromagnetic coil 2 that opens and closes the main contact 4 is connected to a control power source Vcc via an input switch 1.

7a is an auxiliary a contact which is interlocked with the main contact 4;
They are attached together to a contact support that holds the main contacts 4. This auxiliary a contact 7a is connected to the control power supply Vcc via a resistor 8 connected in series. The contact welding detection device consists of an inverter 5 and an AND circuit 6. The input end of the inverter 5 is connected between the input switch 1 and the electromagnetic coil 2, and the output end is connected to one input end of the AND circuit 6. There is. Further, the other input terminal of the AND circuit 6 is connected between the auxiliary a contact 7a and the resistor 8.

Embodiment 2 Next, FIG. 2 shows a second embodiment. In this embodiment, an auxiliary b contact 7b is used in place of the auxiliary a contact 7a in the first embodiment. The auxiliary B contact 7b is attached to the contact support back to back with the auxiliary A contact 7a, and similarly operates in conjunction with the main contact 4. Further, an inverter 9 is also inserted at the other input terminal of the AND circuit 6.

Before explaining the operation of the first and second embodiments, the main contact 4 and the auxiliary a, b contacts 7a,
The operating characteristics of 7b will be explained. The horizontal axis in FIG. 3 shows the stroke (S) of the contact in the opening/closing direction, and the vertical axis shows the load (W) of the electromagnet that opens and closes the contact. In the figure, when the electromagnetic coil 2 of the electromagnet is excited, the contact support starts moving from point A of stroke S0, the auxiliary b contact 7b turns OFF at point B, which has moved by S1, and then point C, which has moved by S2. , the auxiliary a contact 7a turns on, and then S3
The main contact 4 is turned ON at point D, which has moved by the same amount. Then, when the contact support is further moved by S4, the contact support hits the stopper and stops.

[0018] In such a contact stroke, S4
is the wipe amount of main contact 4, and the sum of S4 and S3 is the auxiliary a
The wipe amount of the contact 7a, S1, is the wipe amount of the auxiliary b contact 7b. When the electromagnetic coil 2 is de-energized, each contact moves in the reverse order of the above operation and stops at point A of stroke S0. Here, if any one of the main contacts 4 is welded, even if the electromagnetic coil 2 is de-energized, the contact support will only return by an amount S4 corresponding to the wipe amount. At this time, the auxiliary a contact 7a, which has a larger wipe amount than the main contact 4, remains turned on. In addition, the auxiliary b contact 7b is connected to S3 and S until it returns to ON.
Only the sum of 2 is left in return and remains OFF. In other words, if even one of the main contacts 4 is welded, the auxiliary a contact 7a
remains in the ON state, and the auxiliary b contact 7b remains in the OFF state.

Now, the operation of the first embodiment shown in FIG. 1 will be explained with reference to the time chart shown in FIG. In FIG. 4, P1 is an excitation signal for the electromagnetic coil 2, that is, a drive signal for the electromagnet, P2 is an opening/closing signal for the auxiliary a contact 7a, that is, an opening/closing signal for the main contact 4, and P3 is an inversion signal for the inverter 5. First, at time t1, when the input switch 1 is turned on, the electromagnetic coil 2 is excited, and the main contact 4 and the auxiliary a contact 7a are turned on. At that time, the drive signal P1 and the opening/closing signal P2 become H, but the inverted signal P
3 is L, the detection signal P0 of the AND circuit 6 becomes L.

Next, at time t2, input switch 1 is turned OFF.
When the main contact 4 and the auxiliary a contact 7a turn OFF, the inversion signal P3 changes to H, but since the opening/closing signal P2 changes to L, the detection signal P0 is still L, indicating no abnormality. However, if the main contact 4 is welded when the input switch 1 is turned on again at time t3 and then turned off at time t4, the auxiliary a contact 7a remains on, and the drive signal P
1 is L, and therefore, even though the inverted signal P3 is H, the opening/closing signal P2 becomes H, and the detection signal P0 changes to H. Once in such a state, the detection signal P0 continues to be H even if the input switch 1 is turned on at time t5 and then turned off at time t6. As a result, main contact 4
It turns out that it was welded.

Next, in the second embodiment shown in FIG. 2, when the input switch 1 is turned on, the main contact 4 is turned on, but the auxiliary b contact 7b is accordingly turned off. Therefore, in this state, the inverted signal of the inverter 9 changes to H, but since the inverted signal of the inverter 5 is L, the signal output P0 of the AND circuit 6 is L. However, input switch 1 is OFF
Despite this, if the auxiliary b contact 7b remains OFF due to welding of the main contact 4, the inverted signals of the inverters 5 and 9 both become H, and the signal output P0 becomes H.

According to the above configuration, by extracting the opening/closing signal of the main contact 4 from the auxiliary contacts 7a, 7b which are commonly linked to the main contact 4 of each phase, the conventional contact welding detection device for one phase can detect all Welding of the main contact 4 can be detected, making the device compact and inexpensive. Furthermore, an abnormality can be detected even if the contact support does not return to the OFF state due to some reason other than contact welding.

Embodiment 3 Next, an embodiment will be described in which one contact welding detection device detects welding of the main contacts of a plurality of switches that open and close the same load but do not operate simultaneously. Before that, FIG. 5 shows a configuration in which a contact welding detection device is provided for each switch. The figure is a wiring diagram for driving the motor load in forward and reverse directions with two electromagnetic contactors.
It is connected to power supplies R, S, and T via 0R (for reverse rotation) and a molded circuit breaker 11 located above it. 1 in FIG. 5,
2, 4, 7a and 7b respectively indicate an input switch, an electromagnetic coil, a main contact, an auxiliary a contact, and an auxiliary b contact as in the first and second embodiments, and the subscripts F and R indicate normal rotation and auxiliary b contact, respectively. Indicates that it is for reversing. Further, the numbers inside the electromagnetic contactors 10F and 10R indicate terminal numbers.

Here, when the input switch 1F is turned on, the electromagnetic coil 2F is excited, the main contact 4F is turned on, and the motor 3 rotates in the normal direction. Similarly, when the input switch 1R is turned on, the electromagnetic coil 2R is excited and the main contact 4R is turned on.
Motor 3 reverses. When the main contacts 4F and 4R turn on, the auxiliary a contacts 7aF and 7aR also turn on, and the auxiliary b contact 7bF
, 7bR is turned OFF. In the case shown, the auxiliary contact 7aF,
Two sets of 7bF, 7aR, and 7bR are provided, and one of the auxiliary b contacts 7bF and 7bR is connected to R and S of the power supply.
The electromagnetic coils 2F and 2R connected to each other are inserted into the excitation circuit in a reverse manner to prevent simultaneous injection.

12F and 12R are respectively electromagnetic contactors 1
This is a contact welding detection device installed at 0F and 10R. The numbers on each device indicate the terminal numbers, terminals 1-
2 is a power supply terminal connected to the R and S phases of the power supply, and terminals 3-4
is the output terminal of the trip coil 11a of the circuit breaker 11.
The terminals 5-6 are open/close signal input terminals, and the other auxiliary b contact 7 is connected to the drive circuit of the main contacts 4F and 4R.
It is connected to terminals 31-32 and 41-42 of bF and 7bR, and finally terminal 7-8 is an electromagnet drive signal input terminal and is connected to terminals A1 and A2 of electromagnetic coils 2F and 2R.

The operation of the contact welding detection devices 12F and 12R is substantially the same as that of the second embodiment shown in FIG.
A detection signal is sent by ANDing the opening/closing signal of 7bR with the inverted signal. That is, when the electromagnetic coils 2F, 2R are excited, and when the electromagnetic coils 2F, 2R are not excited and therefore the auxiliary b contacts 7bF, 7bR are ON, no detection output is output, but the electromagnetic coils 2F, 2
Auxiliary b contacts 7bF, 7b despite no excitation of R
When R is OFF, that is, main contacts 4F and 4R are ON, a detection output is applied to the trip coil 11a, and the molded circuit breaker 11 is cut off.

Also in FIG. 5, the main contact 4 is connected according to the present invention.
By taking out the open/close signals of F and 4R from the auxiliary b contacts 7bF and 7bR, contact welding of the main contacts 4F and 4R of each three phases is detected by one contact welding detection device 12F and 12R, respectively. Two electromagnetic contactors 10F and 10R
FIG. 6 shows an embodiment in which contact welding is detected at once by one contact welding detection device. In FIG. 6, two electromagnetic contactors 10F and 10R operate the motor 3 in forward and reverse directions.
The wiring connections are the same as in FIG. 5, but one contact welding detection device 12 is commonly connected to these electromagnetic contactors 10F and 10R.

The difference between the contact welding detection device 12 and the contact welding detection devices 12F and 12R is that one electromagnet drive signal input terminal is added, and a common terminal 7, a terminal 8F for the electromagnetic contactor 10F, and a terminal 8F for the electromagnetic contactor 10R are added. The other configurations are the same except that there are three terminals 8R. Auxiliary b contacts 7bF and 7bR are connected in series to the open/close signal input terminal 5-6, an electromagnetic coil 2F is connected to the input terminal 7-8F of the electromagnet drive signal, and an electromagnetic coil is connected to the input terminal 7-8R. 2R are connected in parallel with each other.

FIG. 7 is a wiring diagram showing the internal structure of the contact welding detection device 12. As shown in FIG. In the figure, 13 is the power supply terminal 1-2
A diode bridge that rectifies the alternating current supplied from the
4 is a relay that outputs the detection output of contact welding from the output terminal 3-4, 14a is its output contact, 15 is a diode bridge that rectifies the alternating current applied to the input terminal 7-8F or 7-8R of the electromagnet drive signal, 16 is a photocoupler that transmits the DC signal to the drive circuit of the relay 14. Also, 1
7 is a transistor that turns on and off the operating circuit of the relay 14; 18 is a capacitor that supplies base current to the transistor 17; 19 is a capacitor that supplies the drive current of the relay 14; capacitors 18 and 19 are direct currents from the diode bridge 13; will be charged.

When the electromagnetic contactors 10F and 10R are open, the auxiliary b contacts 7bF and 7bR are on, so both poles of the capacitors 18 and 19 are short-circuited via these auxiliary b contacts and the resistor 20, and the transistor 17 is turned off. It becomes. Therefore, the relay contact 14 is turned OFF, and no detection output is output from the output terminal 3-4. When the electromagnetic contactor 10F or 10R is turned on, the auxiliary b contact 7
bF or 7bR is turned off, but since the excitation voltage of the electromagnetic coil 2F or 2R is applied to the input terminal 7-8F or 7-8R and the photocoupler 16 is turned on, the capacitors 18 and 19 are still short-circuited, and the transistor 17 is turned off. It remains as it is.

On the other hand, the electromagnetic contactors 10F and 10
Both R are released and input terminal 7-8F or 7-
Both inputs from 8R are gone and photocoupler 16 is turned off.
Main contacts 4F, 4 of either phase
When auxiliary b contact 7bF or 7bR remains OFF due to welding of R, charging of capacitors 18 and 19 starts. When the voltage of the capacitor 18 reaches the Zener voltage of the voltage regulator diode 21, the transistor 17 is turned on.
Then, relay 14 turns on and the detection output goes to trip coil 1.
1a. As a result, the molded circuit breaker 11 is cut off, and the motor 3 is protected. In other words, input terminal 7
A detection output is output only when contact welding occurs by ANDing the electromagnet drive signal from -8F or 7-8R and the opening/closing signal from auxiliary b contact 7bF or 7bR.

According to the embodiment shown in FIGS. 6 and 7, 2
By collectively inputting the opening/closing signals and electromagnet drive signals from the electromagnetic contactors 10F and 10R of each unit to the common contact welding detection device 12, there is no need to detect contact welding for each phase, and there is no need to detect contact welding for each phase. Contact welding of each phase of the two electromagnetic contactors 10F and 10R can be detected by simply adding one input terminal 8F or 8R for the electromagnet drive signal to the contact welding detection device 12.

Embodiment 4 Finally, an embodiment of the present invention in a molded circuit breaker will be described. FIGS. 8 and 9 are examples in which an undervoltage tripping device is used as the tripping device. First, in FIG. 8, reference numeral 11 denotes an electromagnetic contactor 10 that opens and closes the motor load 3.
This is a molded circuit breaker that serves as a higher-level circuit breaker, and has three-phase main contact 4.
are held by an integrally constructed movable contact holder and open and close at the same time. Reference numeral 7a denotes an auxiliary a contact which is operated by a movable contact holder and opens and closes in conjunction with the main contact 4. Reference numeral 22 denotes an electromagnetic coil constituting an undervoltage tripping device, which is normally excited via the input switch 1 consisting of a b contact, and attracts a plunger (not shown) against a drive spring. The structure of the contact welding detection device consisting of an inverter 5 and an AND circuit 6 is substantially the same as that of the first embodiment.

In such a configuration, the molded circuit breaker 1
In the illustrated open state of 1, the drive signal H of the electromagnetic coil 22 is inverted by the inverter 5 and becomes L, and the opening/closing signal of the auxiliary a contact 7a is also L, so the detection signal P0 of the AND circuit 6
is L. Here, when the molded circuit breaker 11 is turned on, the main contact 4 and the auxiliary a contact 7a are turned on. As a result, the opening/closing signal of the auxiliary a contact 7a becomes H, but since the inverted signal of the inverter 5 is still L, the detection signal P0
remains at L.

Next, when the input switch 1 is turned off, the excitation of the electromagnetic coil 22 is released, and the plunger is opened and projected by the force of the drive spring. This plunger mechanically acts on the opening/closing mechanism of the molded circuit breaker 11, turning off the main contact 4 and the auxiliary a contact 7a. As a result, the excitation signal of the electromagnetic coil 22 changes to L, and therefore the inversion signal of the inverter 5 changes to H, but the opening/closing signal of the auxiliary a contact 7a changes to L, so the detection signal P0 is L. However, even though the input switch 1 is turned off, if the auxiliary a contact 7a remains on due to welding of the main contact 4, both inputs of the AND circuit 6 become H, and the detection signal P0 becomes H.

Embodiment 5 FIG. 9 shows an example in which an undervoltage tripping device is used as the tripping device, but in this case, the auxiliary b contact 7b is used as an auxiliary contact that interlocks with the main contact 4, and the AND circuit is used. 6
An inverter 9 is also inserted at the other input end of the inverter 9. In the open state shown in the figure, the inverted signals of inverters 5 and 9 are both L.
Also, the main contact 4 is ON and the auxiliary b contact 7b is OFF.
Since the inverted signal of the inverter 5 is L even in the ON state, the detection signal P0 is L. However, input switch 1
If the auxiliary b contact 7b remains OFF due to welding of the main contact 4 even though the main contact 4 has been turned OFF, the inverted signals of the inverters 5 and 9 both become H, and the detection signal P0 becomes H.

Embodiment 6 FIGS. 10 and 11 show an embodiment in which a voltage tripping device is used as the tripping device of the molded circuit breaker 11. First, Figure 10
, the electromagnetic coil 23 of the electromagnet is connected to the control power supply Vcc via the input switch 1 consisting of an a contact, and the plunger (not shown) is released from the electromagnet and held in place by a return spring. Furthermore, both the excitation signal of the electromagnetic coil 23 and the opening/closing signal of the auxiliary a contact 7a are input directly to the input terminal of the AND circuit 6. In the open state shown, A
The inputs of the ND circuit 6 are both L, and even if the molded circuit breaker 11 is turned on and the main contact 4 and the auxiliary A contact 7a are ON, the excitation signal of the electromagnetic coil 23 is L, so the detection signal P0 will eventually become L. It is.

When the input switch 1 is turned on while the molded circuit breaker 11 is closed, the electromagnetic coil 23 is excited. As a result, the plunger is attracted by the electromagnet against the return spring, and mechanically acts on the opening/closing mechanism to contact the main contact 4.
and turns off the auxiliary a contact 7a. As a result, the excitation signal of the electromagnetic coil 23 changes to H, but the opening/closing signal of the auxiliary a contact 7a changes to L, so the detection signal P0 remains at L. However, even though the input switch 1 is turned on, if the auxiliary a contact 7a remains on due to welding of the main contact 4, both inputs of the AND circuit 6 become H, and the detection signal P0 becomes H.

Embodiment 7 FIG. 11 shows an embodiment in which a voltage tripping device is used as the tripping device and an auxiliary b contact 7b is used as the auxiliary contact. In this case, the excitation signal of the electromagnetic coil 23 is directly input to the AND circuit 6, and the opening/closing signal of the auxiliary b contact 7b is input to the AND circuit 6 via the inverter 9. Hardwire circuit breaker 1
1, if the auxiliary b contact 7b remains OFF due to welding of the main contact 4 even though the molded circuit breaker 11 has been shut off by turning on the input switch 1,
Both the excitation signal of the electromagnetic coil 23 and the inversion signal of the inverter 9 become H, and the detection signal P0 becomes H. Detection signal P
A description of the operation when 0 becomes L will be omitted.

[0040]

According to the present invention, the welding of the main contacts of each phase of a multiphase AC switch is detected by the contact welding detection device for one phase by extracting the switching signal of the main contact from the auxiliary contact interlocked with the switching signal of the main contact. Detection is possible, and the device can be configured compactly and economically. In addition, for multiple switches that do not open or close one load at the same time, the main contact switching signals and electromagnet drive signals from each switch can be input together into one contact welding detection device. Just by adding contacts, it is possible to detect welded contacts of all switchgears.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing a first embodiment of the present invention.

FIG. 2 is a wiring diagram showing a second embodiment of the invention.

FIG. 3 is a diagram illustrating the operating characteristics of contacts in the first and second embodiments.

FIG. 4 is a time chart illustrating the operation of the first embodiment.

FIG. 5 is a wiring diagram illustrating a configuration in which one load is opened and closed by two switches.

FIG. 6 is a wiring diagram showing a third embodiment of the invention.

7 is an internal wiring diagram of the contact welding detection device in FIG. 6. FIG.

FIG. 8 is a wiring diagram showing a fourth embodiment of the invention.

FIG. 9 is a wiring diagram showing a fifth embodiment of the invention.

FIG. 10 is a wiring diagram showing a sixth embodiment of the invention.

FIG. 11 is a wiring diagram showing a seventh embodiment of the invention.

FIG. 12 is a wiring diagram showing a conventional example.

[Explanation of symbols]

2 Electromagnetic coil 3 Load 4 Main contact 7a Auxiliary a contact 7b Auxiliary b contact 22 Electromagnetic coil 23 Electromagnetic coil

Claims (6)

[Claims] 1. A contact of a switch that detects welding of the main contact by ANDing a switching signal generated by the switching operation of the main contact that switches or closes the load and a drive signal that drives an electromagnet that switches or closes the main contact. A contact welding detection device for a switch, characterized in that an auxiliary contact is provided that interlocks with a main contact, and a switching signal for the main contact is extracted from the auxiliary contact. 2. The auxiliary contact is an a-contact, and welding of the main contact is detected by the AND of the opening/closing signal of the auxiliary a-contact and a signal obtained by inverting the drive signal of the electromagnetic coil. The contact welding detection device for the switch described. 3. The auxiliary contact is a b contact, and welding of the main contact is detected by the AND of a signal obtained by inverting the opening/closing signal of the auxiliary b contact and a signal obtained by inverting the drive signal of the electromagnetic coil. The contact welding detection device for a switch according to claim 1. 4. A contact of a switch that detects welding of the main contact by the logical product of a switching signal generated by the switching operation of the main contact that switches or closes the load and a drive signal that drives an electromagnet that switches or closes the main contact. In the welding detection device, the switching signals of the main contacts of multiple switches that open and close the same load but do not operate simultaneously, and the drive signals of the electromagnets of each switch that opens and closes each of the main contacts are combined together. A switch contact welding detection device characterized by inputting an input. 5. The switching system according to claim 4, wherein switching signals for auxiliary b contacts interlocked with the main contacts of each switch are input in series, and drive signals for electromagnets of each switch are input in parallel. Switch contact welding detection device. 6. Welding of the main contacts is performed by ANDing a switching signal generated by opening/closing operations of the main contacts of the molded circuit breaker and a drive signal for driving an electromagnet of a tripping device that opens the main contacts. In the contact welding detection device of the switch to detect,
A contact welding detection device for a switch, characterized in that an auxiliary contact is provided that interlocks with the main contact, and a switching signal for the main contact is extracted from the auxiliary contact.