JPH0517776B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a relay failure detection system that automatically detects failures in relays or magnetic switches (hereinafter simply referred to as relays) provided in drive circuits for motors and other loads. It is related to the device.

[Conventional technology]

Large currents and high voltages are used to drive motors in hoists, cranes, and other large processing machines. Therefore, it is dangerous to directly perform opening/closing operations manually when starting/stopping operations. For this reason, when opening and closing the drive circuit, a relay is used that opens and closes the high-voltage, large-current drive circuit with a small current.

In this case, the lifespan of the relay is uneven depending on the frequency of use, voltage and current value, etc. In particular, when the connection of one phase of a three-phase AC power supply becomes uncertain, the system becomes so-called single-phase operation, which is dangerous as it may cause burnout or other accidents. Furthermore, if the relay is welded, the device will run out of control, resulting in great damage to people and property. For this reason, the inventor of the present invention previously proposed a relay failure detection device that automatically detects when a relay failure occurs and issues a signal (Japanese Patent Laid-Open No. 58-241603).

[Problem to be solved by the invention]

In this case, the means for emitting the signal may be to open a switch (for example, a no-fuse breaker, hereinafter simply referred to as NFB) of a common drive circuit for each load. Various relays are conceivable as a means of opening and closing this NFB operating circuit, but it is desirable that the relay operating power supply has a small capacity, so it is recommended to use a solid state relay (hereinafter referred to as SSR) such as a triac, which operates with a minute trigger current. It is preferable because it can be However, in order to open the NFB operation circuit from the relay failure detection device provided in the relay operation circuit for each load, the SSRs are connected in parallel. However, the output section of an SSR consists of a triax, and this triax normally generates a small amount of leakage current even when it is off. Therefore, it is not preferable to connect these SSRs in parallel because leakage current is accumulated and even when each SSR is in an OFF state, the output side is often in an ON state.

In view of the above, the present invention provides only one output signal generation means for opening the NFB operating circuit, which simplifies the configuration, and even when an SSR is used as the means, only one output signal generation means is required. It is an object of the present invention to provide a crane failure detection device that does not cause malfunctions due to the above-mentioned leakage current.

[Means to solve the problem]

To achieve the above object, the crane failure detection device of the present invention includes a drive current detection means installed in a drive circuit connecting a power source and a load, and an operation current installed in an operation circuit of a relay for opening and closing the drive circuit. It is equipped with a detection means and a signal generation means, and compares the detection signals from both of the detection means, and when either one of the detection signals fluctuates independently of the detection signal from the other, a discrimination circuit operates, thereby generating an output signal. A relay failure detection device that activates a generating means, the relay failure detection device is composed of one base unit and one or more slave units, and the base unit has all the functions described above, and the slave unit has all the functions described above. The machine has a drive current detection means, an operation current detection means, and a discrimination circuit, and, in place of the output signal generation means, is equipped with a terminal for transmitting this signal to the main machine.

In this case, it is preferable that a current transformer is used as the drive current detection means, and that this current transformer is used as the operating power source of the relay failure detection device itself.

Further, it is preferable that the switching device of the signal generating device uses a solid state relay or a contact relay.

〔Example〕

First example 1 to 3 show a first embodiment.

A plurality of, for example, three, loads 2a, 2b, and 2c are connected to the common drive circuit 1, and a no-fuse breaker (hereinafter referred to as NFB) 3 having a shunt circuit with a trip is provided. Branch drive circuits 4a, 4b, 4c connected to the respective loads 2a, 2b, 2c include circuit opening/closing relays 5.
a, 5b, and 5c are provided. However, MC indicates a magnetic coil and PB indicates a push button.

The relay failure detection device 10 for each of the relays 5a, 5b, 5c includes a plurality of detection members 11, 12,
It consists of 13 and more. Hereinafter, the detection member 11 will be referred to as the main unit, 1
2 and 13 are called slave units. The main unit 11 includes a drive current detection means 15 provided in the branch drive circuit 4a, an operation current detection means 15 provided in the operation circuit 6a for the relay 5a, and a judgment that determines the quality of the relay 5a based on input signals from both means 14 and 15. circuit 1
6 and signal generating means 17.

The drive current detection means 14 utilizes a current transformer, and as shown in FIG. (This example shows an example in which the wire is simply passed through the wire.) In this case, a different induced voltage is generated for each phase. That is, as is well known, when the R, S, and T phases are passed through the detection coil 14 or wound with the same number of turns, they interfere with each other and no voltage is generated in the detection coil 14. Therefore, by making the number of turns of each phase different as described above, the induced voltages for each phase become unbalanced, and an output voltage can be obtained at the detection coil 14. The discrimination circuit 16 stores this information, and when any one phase is disconnected, it detects the accompanying fluctuation in the induced voltage. In this embodiment, the power source for driving the main unit 11 is the current obtained from the drive current detection means 14. As a result, base unit 1
1 can be omitted.

The operation current detection means 15 similarly uses a current transformer to detect the presence or absence of an operation current, and its output terminal is connected to the discrimination circuit 16.

The signal generating means 17 is the NFB operating circuit 1 in this example.
It is designed to conduct 8 times and is mainly composed of a solid state relay (hereinafter referred to as SSR) such as a triack.

The slave units 12 and 13 have the same structure, and one slave unit 12 will be described below. The base unit 11 is connected to the slave unit 12.
Similarly, it includes a drive current detection means 20 for the branch drive circuit 4b, and an operation current detection means 21 and a discrimination circuit 22 provided in the operation circuit 6b of the relay 5b. However, the signal generating means 17 provided in the base unit 11
It is something that lacks.

Each of the detection means 20 and 21 is equipped with a current transformer like the main unit 11, and is equipped with a signal transmission terminal 23,
It is connected to the main unit 11 by a connection cord 24, and when an abnormality is detected in the relay 5b, the signal generating means 17 provided in the main unit 11 is activated. Note that the slave device 12 also has a drive current detection means 20 in the same way as the parent device 11.
The output from the terminal is used as a driving power source for the slave device 12.

For the other handset 13, parts having the same function are given the same reference numerals, and explanations thereof will be omitted. However, 6c
is an operating circuit for relay 5c.

[Effect]

This embodiment has the above-mentioned configuration, with relays 5a,
If 5b and 5c are normal, the relay operation circuit 6
When any one of a, 6b, and 6c, for example 6a, is turned on and a drive current is applied to the load 2a, both the drive current detection means 14 and the operation current detection means 15 emit a signal current, and the discrimination circuit 16 This is not determined and the signal generating means 17, that is, the SSR is not activated. The same applies when all relay operation circuits 6a, 6b, 6c are turned off and each branch drive circuit 4a, 4b, 4c is also turned off.

However, one of the relays 5a, 5b, and 5c, for example, relay 5b, becomes defective, and the relay operation circuit 6
When current flows through the three phases or any two phases of the branch drive circuit 4b even if b is in the OFF state,
The handset 12 determines this in the determination circuit 22,
Signal generating means 17 provided in the base unit 11, that is, SSR
is turned on, the NFB operating circuit 18 is made conductive,
Open NFB3.

FIG. 3 is a plan view of the base unit 11. Terminal 1 in the diagram
9a and 19b are connection terminals 19c of the operating circuit 6a,
19d is NFB operating circuit connection terminal, 19e~19
g is a connection terminal for the handsets 12 and 13;

Second example FIG. 4 shows a second embodiment of the invention.

Each load 31a, 31b, 31c shown in this example
A thick wire is used in the common drive circuit 30 to pass a large current, and when a current transformer is used as the drive current detection means as in the above-mentioned embodiment, it is not possible to wind the drive circuit wire around the detection coil. An example of application is shown.

The relay failure detection device 32 includes two detection members 3
3 and 34, hereinafter the detection member 33 is the main unit,
The detection member 34 is called a child device. The master device 33 includes a current transformer 36 for any one phase, for example, the R phase, in the drive circuit 30, a judgment circuit 38, a signal generation means 40, and an operation current detection means 51 provided in the relay operation circuit 42.

However, the current transformer 36 has a structure in which the R phase is simply passed through the detection coil (same as the R phase in FIG. 2), and the signal generating means 40 is also mainly based on the SSR provided in the NFB operating circuit 41, as in the previous example. configured.

The slave unit 34 includes a current transformer 37 and a relay operation circuit 42 for another phase in the drive circuit 30, for example, the T phase.
The operating current detection means 43 and both means 3 provided in
It is provided with a judgment circuit 50 that judges whether the relay is good or bad based on the input signals 7 and 43, and a signal transmission terminal 45 that is connected to the main unit by a connection cord 46.
Current transformer 37 and current transformer 3 provided in the parent device 33
6 constitutes a drive current detection means 35.

Each load 31a, 31 is connected to the relay operation circuit 42.
Relay 44a for forward/reverse drive with respect to b, 31c,
44b...44f are provided in parallel, and when any one of the relays is turned on, the operating current is detected by the operating current detecting means 51, 43.

Note that the operating current detectors 51 and 43 are current transformers as in the previous example. In the figure, PB1, PB2...
...PB4 are all interlock type push button switches.

Further, in this example, the drive power for the relay failure detection device 32 is based on the current obtained from the drive current detection means 35.

[Effect]

This embodiment has the above configuration, and each relay 44
a, 44b...44f are normal, when turning on any relay, for example relay 44a, and applying a drive current to the load 31a for it,
Drive current detection means 35 and operation current detection means 5
1 and 43 both generate signal currents, and the discrimination circuit 5
0.38. Also, all relays 44
When a, 44b, . . . , 44f are OFF, no current flows in the drive circuit 30 either. In either case, the discrimination circuits 50, 38 are connected to the signal generating means 40, i.e.
The SSR is never turned on (although this is the case when the current obtained from the drive current detection means 35 is used as a power source as in this example, and in the latter case, the relay failure detection device 32 itself is also in the OFF state).

Next, even if one of the relays 44a, 44b, . 3
5 is activated, and the discrimination circuits 50 and 38 or 5
A signal current is applied to either 0 or 38. As a result, the discrimination circuits 50 and 38 turn on the signal generating means 40, ie, SSR, and open the NFB 39, as in the previous example.

However, in this case, even if any one relay fails, the NFB is opened and the other relay circuits are turned OFF, but normally each relay is used as a set to control a crane or hoist, etc. However, if any one of the relays is out of order, operating other loads may cause a risk of personal injury or damage to the transported objects or equipment, so it is preferable to shut off all loads.

Further, in this embodiment, two current transformers 36 and 27 are used as the drive current detection means 35, and they are provided in the main unit 33 and slave unit 34, respectively.
6 and 37 may be provided on the base unit 33 or the slave unit 34. In addition, operation current detection means 51, 43
shows an example in which the relays 44a, 44b...44f are provided in the common reel operation circuit 42, but the slave unit 34
are connected to each relay 44 as shown by the chain line in FIG.
Branch operation circuits 47a, 47b...47f of handsets 48a, 48b are connected to branch operation circuits a, 44b...44f, respectively.
. . . 48f may be provided, and each child unit may be provided with an operation current detection means similar to that described above.

〔Effect of the invention〕

According to the present invention, the relay failure detection device is constituted by a master unit and a slave unit, and the means for generating signals such as NFB opening is provided only in the master unit, and all signals from the slave unit are input to the master unit. Since the above-mentioned signal generation means is activated in the signal generation means, the circuit configuration for the signal generation means is simplified, and therefore only one output relay is required, and not only a contact relay but also an SSR can be used as the signal generation means. It has the advantage of being able to be used in any situation.

[Brief explanation of drawings]

1 to 3 relate to the first embodiment, FIG. 1 is a schematic explanatory diagram of the relay failure detection device of the present invention applied to a three-phase AC circuit, FIG. 2 is a perspective view of the drive current detection means, and FIG. Figure 3 is a plan view of the main unit excluding the top cover.
FIG. 4 is a schematic explanatory diagram of a second embodiment of the present invention. 1, 30 are drive circuits, 2a, 2b, 2c, 31
a, 31b, 31c are loads, 5a, 5b, 5c,
44a, 44b...44f is a relay, 6a, 6
b, 6c, 42 are operating circuits, 10, 32 are relay failure detection devices, 11, 33 are main units, 12, 13,
34, 48a, 48b... 48f is a slave unit, 14,
20, 35 are drive current detection means; 15, 21, 5;
Reference numerals 1 and 43 are operating current detection means, 17 and 40 are signal generation means, and 23 and 45 are signal transmission terminals.

Claims (1)

[Scope of Claims] 1. A drive current detection means disposed in a drive circuit connecting a power source and a load, and an operation current detection means and signal generation means disposed in an operation circuit of a relay for opening and closing the drive circuit, A relay failure detection device that compares the detection signals from both of the detection means and operates a discrimination circuit when either one of the detection signals fluctuates independently of the detection signal from the other, thereby activating the output signal generation means. The relay failure detection device consists of one master unit and one or more slave units, and the master unit has all of the above functions, and the slave units have drive current detection means, operation current detection means, and one or more slave units. 1. A relay failure detection device comprising a detection means and a discrimination circuit, and a terminal for transmitting this signal to a base unit in place of the output signal generation means. 2. The relay failure detection device according to claim 1, wherein the drive current detection means is a current transformer, and this current transformer is used as an operating power source for the relay failure detection device itself. 3. The relay failure detection device according to claim 1, wherein the switching device of the signal generator is a solid state relay or a contact relay.