JPS62117226A - Detector of disability of breaking of switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for detecting the inability to open/close due to a main contact failure of a switch that selectively supplies power supply current to a load such as an electric motor.

[Conventional technology]

Conventionally, the fourth circuit was used to supply the entire power supply current to the motor.
The device shown in the figure is known. In the figure, (1) is a motor, (2) is a 6-phase AC power supply, (3) is a circuit breaker, and (4) is a 6-phase AC power supply.
is a switch, and a circuit breaker (3) and a switch (4) are connected in series between an electric motor (1) and a five-phase AC power source (2). The quick breaker (3) can normally be opened and closed manually using a V, and when an overcurrent flows through a motor, etc., the quick breaker (3) is automatically opened to cut off the current. It has become. Further, by fully energizing the interrupting mechanism (5) using an external signal, the entire circuit breaker (3) is forcibly opened to interrupt the current. In addition, the switch (4) has main contacts (4a) to (4c) composed of pairs of fixed contacts and movable contacts, as well as an electromagnetic coil (6>), and the electromagnetic coil ( 6), the main contacts (4a) to (4c) are closed.

In the power supply current supply circuit configured as described above, for example, the circuit breaker (3)? After the motor circuit is in the closed state KL by manually closing V, the main contact (
4a), (4b) and (4c) are closed or opened.

As a result, power supply current is supplied or stopped from the six-phase AC power supply (2) to the electric motor (1). These circuit breakers (3)
When the switch (4) is in the closed state, that is, when power is being supplied to the motor (1), an overload exceeding the rated value of the motor (1) due to a failure of the motor (1), etc. If the current continues to flow for a certain period of time or if a short circuit current flows, the energizing circuit of the motor is automatically cut off by the quick disconnect switch (3), and the motor (1) or the switch (3) is automatically disconnected.
) and other disasters will be prevented.

[Problem that the invention seeks to solve]

In the power supply current supply circuit as described above, the following phenomenon occurs due to an abnormality in the switch (4).

■ When the switch (4) closes, the main contacts (4a) to (
Some welding occurs to either the fixed contact or the movable contact that forms the pair of 4c), so although the electromagnetic coil (6) is de-energized and the switch (4) is set to the open condition, the main contact (4a) ~(4c) cannot be opened, and the power supply current continues to flow.

■ The melting phenomenon of the main contacts (4a) to (4c) as described above does not occur, that is, the electromagnetic coil of the switch (4) (
6) Even if the main contacts (4a) to (4c) are opened with full energization, the arc generated between the fixed contact and the movable contact fails to extinguish, and the arc current continues to flow.

In these cases, the power supply current that continues to flow is usually less than the rated current value of the motor (1), so the circuit breaker (3)
) cannot automatically shut off the circuit. As a result, there was a problem in that serious disasters often occurred in the circuit.

This invention was made to solve all of these problems, and when the main contacts of the switch (4) are set to an open condition, the main contacts (4a) to (4c) are welded and the arc is extinguished. Detection of sustained current caused by a failure, protection of the power supply current supply circuit including the switch (4) by opening the quick breaker based on the detection, and malfunction due to strong impact during the opening/closing operation of the switch (4) The overall purpose is to realize a switch failure detection device that is equipped with various functions to prevent problems and maintain high reliability over a long period of time.

[Means to solve all problems]

The unbreakable detection device for a switch according to the present invention includes a signal indicating the presence or absence of current in an electromagnetic coil that opens and closes the main contacts of the switch, and a current transformer or current shunt that detects the presence or absence of current flowing through the main contacts. The circuit is configured to output an alarm signal after an arbitrary set time only when current continues to flow through the main contact even though the main contact is in an open condition. It is something.

[Effect]

In this invention, when the main contacts of a switch are set to an open condition, the main contacts are welded due to an abnormality in the switch and cannot be opened, or even if the main contacts are opened, the arc that occurs is extinguished. When a failure occurs, an alarm signal indicating an abnormality is output, and this output (No. Protect the supply circuit.

[Embodiments of the invention]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. Portions indicated by symbols (1) to (7) and (4a) to (4c) are the circuit diagrams of the conventional device shown in FIG. This is similar to i1. al is a switch failure detection device according to an embodiment of the present invention, and terminals (11a) and (11b) connected to both terminals of the electromagnetic coil (6) are connected to both terminals of the electromagnetic coil (6).
), whether or not voltage is applied to '1-, that is, switch (4)
Main contacts (4a) to (4C) are input terminals for signals indicating closing or opening conditions. (81L) and (8b) are current transformers, which are placed on the line from the circuit breaker (3) to the main contacts (4a) to (4C) of the switch (4), and the secondary of these current transformers. A current shunt (9) is inserted in series in the reverse connection circuit. Both ends of this shunt part (9) are connected to the terminals (12a) and (12b) of the unblockable detection device αQ, so that a signal indicating whether or not the main circuit is energized is transmitted between the terminals (12a) and (12b). will be introduced in Terminal (13a
), (L5b) are the output terminals of the failure detection device, and the interrupting mechanism (5) of the circuit breaker (3) and the first operating power source (1) are connected in series between these output terminals. Note that when there is continuity between terminals (13a) and (13b),
That is, the output (on) is configured such that the operating current is supplied to the interrupting mechanism (5). In addition, the terminal (14a
) and (14b) are the source terminals of the unblockable detection device αυ, to which the second operating power supply +16) is connected.

FIG. 2 is a detailed circuit diagram of the unblockable detection device αO shown in FIG. 1. The same reference numerals as in FIG. 1 indicate the same components. (A) is a transformer, (C) is a rectifier circuit, (A) is a smoothing capacitor, 4 is a smoothing resistor, (C) is a Zener diode, (C) is a voltage dividing resistor, and A DC power supply circuit (S) is constituted by FL et al.'s elements (a) to (7). When the full specified AC voltage is applied between the terminals (14a) and (14b), the output terminal (17a) of the power supply circuit (S)
), a positive DC voltage is generated as a reference (for example, DC OV) at the terminal (17c)', and a negative DC voltage is generated at the terminal (17b). ) is a transistor, device, (1)
is a photocabra. Here, the photocabra (ha) is
It consists of light emitting diodes (28a) and (28b) and a phototransistor (28c), and a photocoupler (
1) has a similar configuration. 3 is a solid state relay, which consists of a light emitting diode (30a) and a bidirectional photothyristor (30b).

The G core is a variable resistor, and <30 is a capacitor, and these constitute a time-limiting circuit of a transistor. (to) is a bias resistor for the transistor slope, and (b) to (b) are resistors inserted for current limiting, respectively.

Next, the operation of the unblockable detection device 01 shown in FIG. 1, ie, the circuit example shown in FIG. 2, will be described. First, the terminal (14a
) and (14h), a positive voltage is obtained at the terminal (17m) and a negative DC voltage is obtained at the terminal (17b) based on the terminal (17e) ffi, respectively.
As a result, the circuit α1 becomes operational. Next, the terminal (11
a), (11b) and terminals (12a), (12b)
Continuity between terminals (13a) and (13b) (input on/off) with or without an input signal between them.

The relationship between non-conductivity (output on/off) will be described.

The first case is a case where the input signals between the terminals (11a) and (11b) and between the terminals (12a) and (12b) are both absent (that is, the input is off). In this case, the photocoupler (c) and the light emitting diode (28
a), (28b), (29a)-(29b) do not emit light, so the phototransistor (28e).

(29) Both are in the cutoff (high impedance) state V. Therefore, the base current of the transistor is not supplied, so the transistor is cutoff. Therefore, the light emitting diode of the solid state relay
A) is not energized and therefore does not emit light, so the bidirectional photothyristor (30b) becomes non-conductive. the result,
There is no continuity (output off) between the output terminals (13a) and (13b).

The second case is a case where the input signals between the terminals (11&) and (11b) and between the terminals (12a) and (12b) are both present (ie, the input is on). In this case, the light emitting diodes (28a), (28b), and (29a).

(29b) and phototransistor (28).
c) , (29e) are both VC on (low impedance)
However, because the resistor (G) exists and the phototransistor (29c) is on, the 11th position of the base terminal uQ of the transistor (A) is the potential of the reference terminal (17c) (this is the potential of the transistor (I)). ), the base current of transistor (2) is not supplied. Therefore, as in the first case, there is no continuity between the output terminals (13a) and (13b) (output off).

In the sixth case, there is no input signal between the terminals (11a) and (11b) (input off), and the terminals (12m) and
This is a case where the input signal between (12b) is present (input on). In this case, the phototransistor (29c) is in the on (low impedance) state and the transistor (28e) is in the cutoff (high impedance) state, so the phototransistor (29e), the resistor (c), and the variable resistor 0 Base current is supplied to the transistor through ■. As a result, the transistor is turned on, the light emitting diode (30a) of the solid state relay (2) is energized, and the bidirectional photothyristor (30b) is then conductive. That is, the output terminals (13a) and (13b) are electrically connected (output is turned on).

In the fourth case, there is a human input signal between the terminals (11a) and (11b) (input is on), and the terminal (12a) is present.

(12b) There is no input signal (input off). In this case, the phototransistor (29e) is cut off and the transistor (28c) is on, so the terminal (
The potential for 1 second is significantly lower than the potential at the terminal (17e). As a result, the output terminal (
13m) and (13b) are non-conductive (output off).

Based on the above results, the sixth case, that is, the terminal (11
The output terminal (13a) only when there is no input signal between terminals (12a) and (11b) (input off) and there is an input signal between terminals (12a) and (12b) (input on).

(13b) becomes conductive (output on). However, this is in a steady state V, and at the moment when the input signal condition is satisfied in the sixth case, the capacitor is 0.
Due to the presence of resistance, the transistor voltage does not turn on. Therefore, the voltage between the terminals of the capacitor G is the variable resistor Ω force,
It is charged with a time constant determined by the capacitor P3■ and the bias resistor (to), and after the potential of the terminal OgJ rises to a certain specified value, the transistor turns on, and the voltage between the output terminals (L5a) and (13b) is conducts (output #:/). This output-on operation delay time can be adjusted individually using a variable resistor 0υ.

Since the switch failure detection device 01 has the above-mentioned functions, in FIG.
) in which power supply current is supplied to the motor (1), the voltage across the terminals of the electromagnetic coil (6) is introduced between the terminals (11m) and (11b) as an input signal.

In addition, since the secondary induced currents of the current transformers (8a) and (8b) are flowing to the current shunt (9), this is connected to the terminal (12).
It is introduced as an input signal between a) and (12b).

This corresponds to the second case, so the terminal (15 m
) and (13b) are non-conductive (output off).

Next, when the power supply from the control power supply (7) to the electromagnetic coil (6) is stopped and the main contact of the switch switch (4) is opened and the motor circuit is cut off, the terminal (11a ).

The input signal between (11b) becomes null (input off), and at the same time, no current flows in the motor circuit, so the shunt (9)
No current flows through either. Therefore, the terminals (12a), (1
The input signal between 2b) is null (input off). This corresponds to the first case, so the terminals (13a) and (1
3b) is non-conductive (output off).

However, as mentioned above, even if the energization to the electromagnetic coil (6) is stopped and the main contact of the switch (4) becomes open, one of the main contacts (4 &) to (4c) will be welded. Even if the main contacts of the switch (4) are not opened, or even if the main contacts are opened normally without welding, if an arc persists between the main contacts, current continues to flow through the motor circuit. In this case, the input signal between the terminals (11a) and (Ilb) is zero (input off), but the input signal between the terminals (12a) and (Ilb) is zero (input off).
, (12b) is present (input on), this corresponds to the sixth case. Therefore, after a predetermined period of time has passed since this manual condition is satisfied, the terminal (
13a).

(13b) is conductive (output on) and $1 operation (L
An energizing current is supplied from ω to the interrupting mechanism (5) of the circuit breaker (3). As a result, the interrupting mechanism (5) operates and the circuit breaker (
3) is forcibly cut off.

Although the above embodiment applies the present invention to a six-phase AC circuit, it is also applicable to a single-phase AC circuit.
In this case, only one current transformer may be used. Further, in the above embodiment, the present invention is applied to an AC circuit, but it can also be applied to a DC circuit. In this case, the current transformer is unnecessary, and the current shunt (9) is directly inserted into either of the two lines of the motor circuit, and both ends of the current shunt (9) are connected to the terminals of the quick disconnection detection device αO. (11a)
, (11b).

FIG. 6 is a circuit diagram showing an unblockable detection circuit according to another embodiment of the present invention. In the figure, (10') is the second
This is an unbreakable detection circuit equivalent to the one shown in the figure.It uses a rectifier (21") instead of the transformer ■ and the rectifier circuit (c) in Figure 2.
The DC power supply circuit (S') was simplified by using a photocoupler (28') with a base terminal instead of the photocoupler (to), and the resistor (b) was used.
Although the circuit configuration is quite different, such as the addition to 1111=, its operation and effect are almost the same as those shown in FIG. 2 above. The disconnection failure detection device (10') shown in Figure 6 is for both AC and DC use, and when the operating power supply (10 in Figure 1) is DC, the terminal (14a) is connected to the positive terminal, and the terminal (14b)' is connected to the negative voltage. They can be used by being connected to electrodes respectively.

〔Effect of the invention〕

As described above, according to the present invention, two signals are input: a signal indicating that the main contact of the switch (4) is in the open condition, and a signal indicating that current is flowing in the motor circuit at that time. Since the circuit breaker opening signal is output only after a predetermined time limit, the main contact of the switch (4) may be welded or the arc may continue due to failure to extinguish the arc at the time of opening. This prevents malfunctions caused by transient phenomena at . In addition, by switching the 1ti disconnector to the fast-acting state in response to these detected abnormal signals, the power supply current supply circuit including the switch (4) that would otherwise occur due to the continuous supply of the power supply current is This has the effect of effectively preventing disasters.

Further, since the detection device a1 according to the embodiment is mainly composed of non-contact elements such as semiconductors, it has excellent earthquake resistance and impact resistance, and can be made small and compact.

Further, this detection device can be directly mounted on a device that generates a considerable impact when opening and closing the switch (4), and has the effect of providing high reliability in its operation.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a power supply current supply circuit according to an embodiment of the present invention, FIG. 2 is a detailed circuit diagram showing the main parts of the detection device, and FIG. 6 is a detailed circuit diagram of a detection device according to another embodiment. , FIG. 4 is a circuit diagram showing a conventional power supply current supply circuit. In the figure, (1) is the electric motor, (2) is the 6-phase AC power supply, and (3)
is a quick disconnector, (4) is a switch, (4a)-(4b), (4
c) is the main contact, (8m). (8b) is a current transformer, (9) is a current shunt, α09 (10') is a rapid disconnection detection device, (S)
is a DC power supply circuit, ■ is a transformer, qp is a rectifier circuit, (to)
, the device is a photocoupler, and (1) is a solid state relay with a built-in bidirectional thyristor. In addition, the same symbols in each figure indicate the same or equivalent parts〇

Claims (2)

[Claims] (1) A means for detecting the energization state of the electromagnetic coil that controls the opening and closing conditions of the main contact in the switch, and a means for detecting the energization current of the main contact, and each 1. A switch failure detection device, characterized in that a combination of signals controls on/off of a circuit breaker connected in series to the main contact. (2) The switch failure detecting device according to claim 1, wherein the on/off control is constituted by a non-contact component of a semiconductor element.