JPH03159525A - Load controller - Google Patents

Abstract

PURPOSE:To prevent erroneous function and malfunction of an electromagnetic contactor effectively by branching current through a bypass circuit under a state where a current caused by a ground electrostatic capacitance flows through a signal line. CONSTITUTION:A load controller comprises input means 20, 22 for converting a control current signal into a logic signal and providing to a logic operation circuit 12, means 19, 21 for detecting current levels in signal lines 15, 16, means 13 for previously storing the control current signal level under a state where the ground electrostatic capacitance of the signal lines 15, 16 are zero or near to zero, and bypass circuits 23, 26 for shunting current flowing through the signal lines 15, 16 under operating state. The bypass circuits 23, 26 are switched to an operating state when the level detected through the detecting means 19, 21 under a state where current flow through the input means 20, 22 does not match with a level stored in the memory means 13. By such arrangement, erroneous function and malfunction of an electromagnetic contactor 5 can be prevented effectively even when the ground electrostatic capacitances of the signal lines 15, 16, through which control current signal for open/close control of the electromagnetic contactor 5 flow, increases.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention is a system in which a main circuit device such as a molded circuit breaker or an electromagnetic contactor is interposed in the main circuit between a power supply bus and a load. The present invention relates to a load control device, and particularly to a load control device equipped with an operating device that outputs a control current signal for operating a load through a signal line.

(Prior Art) This type of load control device is often used when driving an electric motor, and includes an electromagnetic contactor, an electromagnetic contactor, and a main circuit between a power supply bus and the load for controlling the power on/off of the load. In addition to intervening main circuit devices such as current converters and molded circuit breakers for carrying out overcurrent protection of loads and other functions, the above-mentioned electromagnetic contactors are opened and closed to control the starting and stopping of loads. It is constructed by providing a photographing device including an operation switch for operation and an operation switch for stopping. In particular, in this case, each switch of the operating device is connected to a different signal line connected to the control power line, so that a control current signal of a predetermined level is outputted through each of the signal lines. The electromagnetic contactor is configured to control the opening and closing of the electromagnetic contactor based on the control current signal.

In addition, in recent load control devices, the load
U of control and protection functions: In order to easily deal with food changes, etc., we can appropriately set, add, and cover a large number of control and protection functions by adopting electronic applied technology. A structure that can be changed is also being developed. That is, in this case, a logic operation circuit consisting of a microcomputer is provided, and this logic operation circuit controls the opening and closing of the electromagnetic contactor based on the control current signal from the front S self-operating device, and the current converter. The configuration is such that the operation of the molded circuit breaker and the like is controlled in accordance with the magnitude of the detected main circuit current.

(Three Problems to be Solved by the Invention) By the way, in the negative control device having the above configuration, when the negative Gf is remotely controlled, the signal line connected to the operating device is extended. However, when the signal line is extended in this way, the ground capacitance of the signal line becomes large, so that a state where no control current signal from the drying device is flowing through the signal line is generated. ! 1, current may also flow. Therefore, in such cases, the logic operation circuit reduces the current flowing due to the capacitance to 1
，Re-governed electricity? IItf. There is a risk that the magnetic contactor may be mistakenly identified as No.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a signal line that carries a control current signal for opening/closing control of an electromagnetic contactor even when the ground capacitance of the signal line increases.
An object of the present invention is to provide a negative tJ control device that can effectively prevent malfunctions and malfunctions of the electromagnetic contactor.

[Aside from the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a main circuit device such as a magnetic contactor and a molded circuit breaker in the main circuit of the power bus and the load 12jJ. ? [an operating device that outputs a control current signal for operating the load through a signal line;
A logic arithmetic circuit that performs opening/closing control of the electromagnetic contactor based on the control current signal and operation control of the molded circuit breaker according to the magnitude of the main circuit current based on a pre-stored program. In the samurai control device provided, an input means for converting the control current signal into a logic signal and providing it to the logic operation circuit, a detection means for detecting the level of the current flowing in the signal line, and a ground terminal of the signal line. A storage means that stores in advance the level of the control current signal when the capacitance is zero or close to this, and a bypass circuit configured to shunt the current flowing through the signal line when the signal line is activated are provided. In the above, the logical operation circuit is configured to switch the bypass circuit to an operating state when the detection level by the detection means does not match the storage level of the storage means with current flowing through the input means. be.

(Operation) A control current signal outputted from the operating device through the signal line is converted into a logic signal by the input means and is applied to the logic operation circuit.

At this time, if the ground capacitance of the signal line is relatively large, that is, if the signal line is extended relatively long, a relatively large current may flow through the signal line. Therefore, in such a case, in the input means,
There is a possibility that the current flowing as described above may be converted into a logic signal similar to the control current signal.

However, in this case, the current caused by the capacitance and the current level stored in the storage means (when the ground capacitance of the signal line is at or close to zero, that is, when the signal line is relatively short) (control current signal level) does not match. Therefore, the bypass circuit is switched to the operating state by the logic operation circuit. As a result, the level of current applied from the signal line to the input means decreases, so even if a current flows due to the ground capacitance of the signal line, this will cause the control current signal to flow in the input means. Similarly, it will not be converted into a logical signal. As a result of this, the opening/closing control of the electromagnetic contactor by the logic operation circuit based on the logic signal is always performed accurately.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In the figure, only the portions of the load control device incorporated in a control center or the like that are related to the main point of the electrical power of the load control device and the like are shown. In the same figure, three-phase power supply bus 1 and negative
The main circuit 3 between the electric motor 2 and the main circuit 3 includes a molded circuit breaker 4, an electromagnetic contactor 5, and a current converter 6 for detecting the main circuit current, which are mainly main circuit devices. The negative 47 side of the molded circuit breaker 4 is connected to the primary side of the operating pressure transformer 7, and the control bus 8.9 of 1 sentence/1 is connected to the secondary side of this transformer 7. A protective fuse 10 is interposed in the control I line 8.

Although not shown, a power supply circuit for generating a constant DC voltage is connected between the control bus bars 8 and 9, and power is supplied from this power supply circuit to the control circuit device 11 described below. .

The control circuit device 11 is mainly composed of a logical performance circuit 12 made up of a microcomputer. This logic operation circuit 12 is: self +1! The protection operation through the wiring circuit breaker 4 and the opening/closing operation of the electromagnetic contactor 5 are executed based on the control program and function data stored in the storage circuit 13 and each input signal described later. Lee J
L. The output control part related to the protective operation by the molded circuit breaker 4 is not shown in the figure.

The A-D conversion circuit 14 is configured to digitally convert the voltage signal indicating the main circuit current detected by the current conversion S6, and the conversion output is sent to the logical operation circuit as a data signal for protective operation by the molded circuit breaker 4. given to 12.

Two signal lines 15.1 each connected at one end to the control bus 8
6, a normally open type start operation switch 17 and a normally closed type stop operation switch 18 are interposed as operation devices, respectively. As a result, each state rl! in which the operation switches 17 and 18 are turned on! Control current signals Son and Sofl' are output to corresponding signal lines 15 and 16, respectively.

The other end of the signal line 15 is connected to the control bus 9 via a current detection circuit 19 as a detection means and an excitation coil 20a of a relay 20 as an input means. The other end of the signal line 16 is connected to the control bus 9 via a current detection circuit 21 as a detection means and an excitation coil 22a of a relay 22 as an input means.

An open type relay contact 20b that the relay 20.22 has,
22b has one end connected to the control bus 8, and the other end connected to the input port of the logic operation circuit 12 via a rectifying and smoothing circuit (not shown).

Therefore, the starting operation switch 17 is turned on and the signal line 1
5, when the control current signal Son is output, the excitation coil 20a is excited by the current signal Son and the relay contact 20b is turned on, so that the control current signal S
on is converted into a logic signal and input to the logic operation circuit 12.

Also, when the stop operation switch 18 is turned on, the signal line 16
When the control river current signal Sof'T is output, the current signal Sorr excites the excitation coil 20a and turns on the relay contact 22b, so the control current signal Sorr is converted into a logic signal and sent to the logic operation circuit. 12 will be input.

Note that the current detection circuits 19 and 21 are configured to detect the level of the current flowing through the corresponding signal lines 15 and 16, and provide the logic operation circuit 12 with a digital signal indicating the detected level.

The bypass circuit 23 interposed between the signal line 15 and the control bus 9 is configured by connecting a switching circuit 24 turned on by a command from the logic operation circuit 12 and a capacitor 25 in series. As a result, the switching circuit 2
4 is turned on, the current flowing through the signal line 15 is shunted through the capacitor 25. Signal line 1
The bypass circuit 26 interposed between the control bus 9 and the control bus 9 is configured by connecting a switching circuit 27 turned on by a command from the logic operation circuit 12 and a capacitor 28 in series. As a result, when the switching circuit 27 is turned on, the signal 1; I1 6 J. The flowing current is shunted through the capacitor 28 as follows.

The driving port path 29 is operated by the logical operation 3'>IFj of the port path 12, and in the operation ν state, the excitation coil 5a of the seventh magnetic contactor 5 is controlled by the control busses 8 and 9. configured to connect between

Now, below, the performance of the logic operation circuit 12 will be explained together with the related operation 111.

That is, when using the load control device with the above configuration for long-term use, the control current signal S on, when the capacitance of the signal lines 15 and 16 is zero or close to zero (normal state)
The current detection circuit 19.21 determines the level of S orr.
The detected level is stored in the storage circuit 13 through the logic operation circuit 12.

Thus, in the initial state where the electromagnetic contactor 5 is turned off, when the control current signal Son is output to the signal line 15 in response to the turning on of the starting operation switch 17, the current signal S
ON is converted into a logic signal by the relay 20 and a DC smoothing circuit (not shown), and is input to the logic operation circuit 12. Then, in the logical arithmetic circuit 12, the two drive paths ijJIiD are kept in the operating state, and thereby the excitation coil 5a is energized and the electromagnetic contactor 5 is turned on.

In addition, in the ON state of such a magnetic contactor 5, %
When the control current signal Soff is output to the signal line 16 in response to the turning on of the K' stop operation switch l8, the current signal Sofr is sent to the relay 22 and the DC if slip [! !
I'tt! It is converted into a logic signal by I and logic P4! The signal is input to the arithmetic circuit 12. In this case, in the logic operation circuit 12, the operating states of the two drive circuits are determined, and as a result, the excitation coil 5a is cut off and the electromagnetic contactor 5 is turned off.

By the way, when the ground capacitance of the signal line 15.16 is relatively large, that is, when the signal line 15.16 is extended relatively long, the signal 815.16
A relatively large current may flow through the Therefore, in such a case, the current as described above will cause the relay 20.22 to
malfunctions, and the 1.11 current signal S on, S
There is a possibility that a logic signal similar to that in the case where orl' flows is mistakenly input to the logic operation circuit 12. Physically, for example, when the ground Tp capacitor plate of the signal line 15 is in a large state, current flows through the signal line 15 even though the starting operation switch 17 is in the OFF state, and this causes the relay 2o Some people are addicted to malfunctioning. In addition, when the ground D capacitance of the signal line 16 is large, the stop operation switch 17
Current may flow through the signal line 16 even though the relay 22 is turned off, which may cause the relay 22 to malfunction.

Therefore, when such a malfunction of the relay 20.22 is caused, each current caused by the capacitance of the signal line 15.16 and the current level stored in the memory circuit 13 (signal line 15.16 The levels of the control current signals Son and Sorr do not match when the ground capacitance of the signal line 15 and 16 is at or close to zero, that is, when the signal lines 15 and 16 are relatively short. When such a mismatch occurs, the logical operation circuit 12 turns on the switching circuit 24.27 to switch the bypass circuit 23.26 to the operating state, thereby shunting the current to the capacitor 25.28.

Then, the level of the current given to the relays 20 and 22 from the signal lines 15 and 16 decreases, so that the signal!
Even if a current flows through 1115.16 due to its ground capacitance, relay 20.22 will not be operated erroneously. As a result, the current caused by the ground capacitance is not converted into a logic signal and input to the logic operation circuit 12, and the opening/closing control of the electromagnetic contactor by the logic operation circuit 12 is controlled by the signal line 15. 16 is always performed accurately regardless of the length.

[Effects of the Invention] According to the present invention, as is clear from the above description, there is provided a load control device in which opening/closing control of an electromagnetic contactor is performed based on a control current signal outputted from an operating device through a signal line. In this case, when a current flows through the signal line due to the χ·1 ground capacitance, the current is shunted by a bypass circuit, so the signal line can be extended for remote cropping, etc. Therefore, even when the ground capacitance of the signal line increases, malfunctions and malfunctions of the electromagnetic contactor can be effectively prevented.

[Brief explanation of the drawing]

The figure is a schematic electrical circuit configuration diagram showing an embodiment of the present invention. In the diagram, 1 is the power bus, 2 is the electric motor (1'1 6 ga),
3 is the main circuit, 4 is the wiring circuit breaker (main r: route equipment), 5
5 is an electromagnetic contactor (main circuit shell), 5a is an exciting coil, 6 is a current converter (main circuit r, vJ!), 8. 9 is a control bus line, 11 is a control circuit device, 12 is a logic calculation circuit, 13
is a memory circuit (memory means), 15.16 is a signal line, 17 is a start operation switch (operation device), 18 is a stop operation switch (pinching device), 19.21 is a current detection circuit (detection means), 20.22 is a relay (input means), 23.26
indicates a bypass circuit, and 2 indicates a drive circuit.

Claims (1)

[Claims] 1. Main circuit equipment such as an electromagnetic contactor and a molded circuit breaker interposed in the main circuit between the power supply bus and the load, and an operating device that outputs a control current signal for operating the load through a signal line; A logic operation circuit is provided that performs opening/closing control of the electromagnetic contactor based on the control current signal and operation control of the molded circuit breaker according to the magnitude of the main circuit current based on a pre-stored control program. In the load control device, input means for converting the control current signal into a logic signal and providing it to the logic operation circuit, detection means for detecting the level of the current flowing in the signal line, and ground static electricity of the signal line. A storage means that stores in advance the level of the control current signal in a state where the capacitance is zero or close to this, and a bypass circuit provided to shunt the current flowing through the signal line in an activated state. , the logic operation circuit is
The load control device is configured to switch the bypass circuit to an operating state when a detection level by the detection means does not match a storage level in the storage means with current flowing through the input means. .