JPH06178438A - Load controller - Google Patents

Abstract

PURPOSE:To materialize properly the maintenance and management of an electromagnetic contactor by judging the life of its electromagnetic contactor accurately with simple constitution. CONSTITUTION:The main circuit 23 between a power bus 21 and a motor 22 is provided with a main circuit utensil such as an electromagnetic contactor 25, etc. A detecting circuit 40 detects the current of the main circuit at breaking operation of the electromagnetic contactor 25, based on the output from a current converter 26, and gives the detection output to a logical operation circuit 31. The logical operation circuit 31 operates an additional value, which becomes larger the larger the current of the main circuit becomes, based on the current of the main circuit and the logical formula to show the relation between a break current and the preset durable number of times of switching, each time the break operation of the electromagnetic contact 25 is performed, and sums up this one by one, and also it shows the result of its total on a display 39. Accordingly, on the display 39, the number of times of switching of the electromagnetic contactor 25 is displayed in the condition that it is compensated according to the magnitude of the break current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device in which a logical operation circuit controls a main circuit device for opening and closing a load such as an electric motor.

[0002]

2. Description of the Related Art A control center is known as an example of a load control device having an opening / closing and protection function for an electric motor or a resistive load.

That is, in the control center, a plurality of units in which appliances such as an electromagnetic contactor, a circuit breaker, a current converter, and an auxiliary relay for control are grouped together for each unit circuit are housed in multiple stages, and each unit is also housed. And a display operation panel including an operation device including a start operation switch, a stop operation switch, and the like.

Further, in recent years, in order to easily cope with the specification change of the unit, by adopting an electronic application technique, a necessary function among a plurality of control and protection functions is appropriately set, added, It is also possible to have a configuration that can be changed. That is, in this case, a logical operation circuit including a microcomputer is provided, and the main circuit device and the display are displayed by the logical operation circuit according to the input signal from the operating device and the magnitude of the main circuit current detected by the current converter. By configuring to control the device,
The control mode can be changed flexibly.

FIG. 7 schematically shows a configuration example of a control center which employs such a logical operation circuit. That is, FIG. 7 shows a schematic circuit configuration for one unit of the control center. The main circuit 3 between the three-phase power bus 1 and the electric motor 2 as a load is a main circuit device. The circuit breaker 4 for wiring, the electromagnetic contactor 5, the current converter 6 for main circuit current detection, and the zero phase current transformer 7 for ground fault current detection are provided. The primary side of the operating transformer 8 is connected to the load side of the wiring breaker 4, and the control buses 9a and 9b are connected to the secondary side of the transformer 8.

The control unit 10 fed from the control buses 9a and 9b via a DC power supply circuit (not shown) is mainly composed of a logical operation circuit 11 composed of a microcomputer. The logical operation circuit 11 includes a start operation switch 12 and a stop operation switch 1, which are operating devices, respectively.
3 and each ON signal from the normally open auxiliary contact 5a of the electromagnetic contactor 5 are received via the input circuit 14, and each signal from the current converter 6 and the zero-phase current transformer 7 is AD converted. The coil 15b for receiving the electromagnetic contactor 5 is controlled via the output circuit 16 while being received via the circuit 15.

The memory circuit 17 stores a control program and function data for executing protection operations such as overload, open phase, undercurrent, ground fault, and control operations such as instantaneous power failure restart and timed restart. Therefore, the logic control circuit 11
The protection operation and the control operation are executed based on the control program, the function data and the input signal. Setting circuit 1
The numeral 8 is composed of a large number of selection switches (not shown) so that the function data stored in the memory circuit 17 can be set and selected as desired at the installation site of the control center.

Since the logical operation circuit 11 thus constructed by the microcomputer is used to control the main circuit equipment and the like, for example, even when the specifications of the unit are changed, the control program for the logical operation circuit 11 is controlled. You will be able to deal with it easily just by changing.

[0009]

A problem in maintaining and managing the control center is the deterioration of each electric component over time. Among them, the electromagnetic contactor 5, which has the highest switching frequency, has an upper limit of the opening and closing life of about 500,000 times, and if the opening and closing operation is performed beyond this upper limit, the contacts may drop out. Will cause a major functional disorder. Therefore, in order to maintain and manage the electromagnetic contactor 5, it is necessary to record the number of times it is opened and closed.

By the way, the switching life of the electromagnetic contactor 5 as described above is a value when the electromagnetic contactor 5 is opened and closed at the rated current, and when the main circuit current at the time of opening and closing is larger than the rated current, It also has the property of shortening the switching life. Further, the main circuit voltage and the power factor at the time of opening / closing the electromagnetic contactor 5 also affect the switching life. Therefore, in a configuration in which the number of times of opening / closing of the electromagnetic contactor 5 is simply recorded, that is, in a configuration in which a factor affecting the opening / closing life of the electromagnetic contactor 5 as described above is not considered at all, the maintenance management thereof can be appropriately performed. I couldn't say that I could do it.

The present invention has been made in view of the above circumstances, and an object thereof is to accurately determine the life of an electromagnetic contactor provided for opening and closing a main circuit with a simple structure. An object of the present invention is to provide a load control device capable of achieving accurate maintenance management of the electromagnetic contactor.

[0012]

In order to achieve the above object, a load control device according to the present invention includes a main circuit device such as an electromagnetic contactor interposed in a main circuit between a power bus and a load,
An operating device for operating the load is provided, and a logical operation circuit for performing control of the main circuit device according to the magnitude of the input signal and the main circuit current by the operating device based on a prestored control program is provided. In the load control device, the current detecting means for detecting the main circuit current at the time of the breaking operation of the electromagnetic contactor is provided, and then the breaking operation of the electromagnetic contactor is performed with respect to the logical operation circuit. The main circuit current detected by the current detecting means and a preset logical expression showing the relationship between the breaking current and the number of endurance switching operations are used to calculate an additional value that increases as the main circuit current increases. It is configured to add a function of sequentially accumulating and a function of displaying the cumulative result on the display unit.

In this case, voltage detecting means for detecting the main circuit voltage during the interruption operation of the electromagnetic contactor is provided, and the main circuit voltage detected by the voltage detecting means during the calculation of the added value by the logical operation circuit. It is also possible to adopt a configuration in which correction is performed such that the higher the value of, the larger the above-mentioned added value.

Further, in the calculation of the added value by the logical operation circuit, in addition to the correction by the main circuit voltage as described above, the main circuit current detected by the current detecting means and the main circuit current detected by the voltage detecting means are detected. The power factor may be calculated based on the circuit voltage, and the correction may be performed such that the added value increases as the power factor decreases.

[0015]

In the load control device according to the first aspect of the present invention, each time the electromagnetic contactor is interrupted, the current detecting means detects the main circuit current during the interrupting operation. The logical operation circuit, each time the electromagnetic contactor breaking operation is performed, based on the main circuit current detected as described above, based on a logical expression indicating the relationship between the preset breaking current and the number of endurance switching, The larger the main circuit current is, the larger the added value is calculated, and the added values thus calculated are sequentially accumulated, and the accumulated result is displayed on the display unit.
Therefore, the display section shows the number of times the electromagnetic contactor has been opened and closed corrected in accordance with the magnitude of the breaking current (specifically, when the breaking current is large, the number of times the electromagnetic contact is opened and closed is the steady current). It will be displayed in a state converted to a value larger than that at the time of shutoff, and the opening / closing frequency data displayed like this is
The data for determining the actual number of times the electromagnetic contactor is actually opened and closed is highly reliable.

In the load control device according to the second aspect of the present invention, when the above-mentioned added value calculated by the logical operation circuit is high in the main circuit voltage during the interruption operation of the electromagnetic contactor (that is, the interruption operation is performed). The larger the influence on the life of the electromagnetic contactor is, the larger the correction will be made.Therefore, the opening / closing frequency data displayed on the display will be used as data to judge the actual durable switching times of the electromagnetic contactor. It will be highly reliable.

According to another aspect of the load control device of the present invention, the logical operation circuit calculates the power factor based on the main circuit current and the main circuit voltage, and when the calculated power factor is low (that is, electromagnetic contact). (When the effect on the life of the container is large)
As a result, the correction for increasing the added value corrected by the main circuit voltage as described above is added. Therefore, it is possible to make the opening / closing frequency data displayed on the display unit more reliable as data for determining the actual durable opening / closing frequency of the electromagnetic contactor.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to a control center will be described below with reference to FIGS.

That is, FIG. 1 shows a control center 1
The circuit configuration for the unit is shown. In FIG. 1, a main circuit 23 is formed between a three-phase power bus 21 and an electric motor 22 which is a load, and the main circuit 23 has a wiring breaker 24 which is a main circuit device. , Electromagnetic contactor 25, current converter 26 for detection that generates a voltage signal according to the main circuit current, and zero-phase current transformer 27 for ground current detection
Is provided. The primary side of the operating transformer 28 is connected to the load side of the wiring breaker 24 in the main circuit 23, and the control bus 2 is connected to the secondary side of the transformer 28.
9a and 29b are connected.

The control section 30 fed from the control buses 29a and 29b through a DC power supply circuit (not shown) is mainly composed of a logical operation circuit 31 composed of a microcomputer. The logical operation circuit 31 includes ON signals from a start operation switch 32 and a stop operation switch 33, which are operating devices, and ON signals and OFF signals from a normally open auxiliary contact 25a of the electromagnetic contactor 25. Is received via the input circuit 34, the signals from the current converter 26 and the zero-phase current transformer 27 are received via the A / D conversion circuit 35, and the operating coil 2 of the electromagnetic contactor 25 is received.
5b is controlled to switch on and off through the output circuit 36. The logical operation circuit 31 also controls the display contents by the display unit 39, which will be described later.

The storage circuit 37 stores a control program and function data for executing protection operations such as overload, open phase, undercurrent, ground fault, and control operations such as instantaneous power failure restart and timed restart. Therefore, the logic control circuit 31
The protection operation and the control operation are executed based on the control program, the function data and the input signal. Setting circuit 3
Reference numeral 8 is composed of a large number of selection switches not shown so that the function data stored in the storage circuit 37 can be set and selected as desired at the installation site of the control center.

Now, the detection circuit 40 as the current detection means
Is adapted to take in each ON signal from the starting operation switch 32, the stopping operation switch 33 and the normally open auxiliary contact 25a of the electromagnetic contactor 25 via the input circuit 34. The detection circuit 40 is adapted to receive the voltage signal from the current converter 26 (that is, the signal indicating the main circuit current) via the A / D conversion circuit 35, and stop the input of the ON signal from the auxiliary contact 25a. The main circuit current ΔI at the set timing (that is, the timing when the electromagnetic contactor 25 is cut off) is taken in and given to the logical operation circuit 31.

Here, in general, between the breaking current of the electromagnetic contactor and the contact life (the number of durable switching times), as shown in FIG. 2, the contact life is given as a function of the breaking current (F1 = F (x1)) exists (however, both the X-axis and the Y-axis in FIG. 2 are logarithmic scales), and this relationship is
It can be approximated by (1). logL = a logI + c (1) However, L = the number of durable switching of contacts (10,000 times), I = (breaking current / rated current) × 100%, a = −2, b = 6.

Therefore, each time the electromagnetic contactor 25 is shut off, the logical operation circuit 31 accumulates a predetermined addition value Lx to the opening / closing frequency data ΣN (initial value is zero) set in the internal memory. The operation is performed, but when accumulated, the main circuit current ΔI given from the detection circuit 40.
Based on (main circuit current at each timing when the electromagnetic contactor 25 is cut off) and the above equation (1), the electromagnetic contactor 25
Is calculated, and the above-mentioned added value Lx is calculated on the basis of the durable switching times L obtained in this way and the durable switching times La (10,000 times) when the 100% rated current is cut off. to correct. Actually, the calculation of Lx = La / L is performed, and the added value Lx thus obtained is used as the opening / closing number data Σ.
Accumulate in N.

Explaining with a concrete example, 100%
When the endurance switching frequency La when the rated current is cut off is 1 million times and the main circuit current ΔI during the breaking operation of the electromagnetic contactor 25 is 200% of the rated value, I = 200, logL = −2log200 + 6 = 1.398, and therefore, the durable opening / closing frequency L is 25 (10,000 times). Therefore, Lx = La / L = 100/25 = 4, and the added value Lx = 4 thus obtained is accumulated in the opening / closing frequency data ΣN. When the main circuit current ΔI during the breaking operation of the electromagnetic contactor 25 is the rated value, I = 100 in the above formula (1), so logL = -2 log100 + 6 = 2, and therefore, the durable switching The number of times L is 100 (10,000 times). Therefore, Lx = La / L = 100/100 = 1, and the added value Lx = 1 is the opening / closing number data Σ.
Will be accumulated in N. Then, the logical operation circuit 31
In this case, the opening / closing frequency data ΣN that gradually increases each time the electromagnetic contactor 25 is shut off as described above is displayed on the display unit 39.
To display.

Therefore, according to the above-described embodiment, the cumulative number of times of opening and closing of the electromagnetic contactor 25 can be grasped based on the number of times of opening and closing ΣN displayed on the display unit 39, and thus, it is grasped in this way. The maintenance of the electromagnetic contactor 25 can be appropriately and easily performed based on the state of the electromagnetic contactor 25. In particular, in this case, the opening / closing frequency data ΣN is data corrected according to the magnitude of the main circuit current ΔI during the breaking operation of the electromagnetic contactor 25, and the actual endurance switching frequency of the electromagnetic contactor 25 is determined. Since the reliability of the data for doing so is high, the life of the electromagnetic contactor 25 can be accurately determined, and as a result, the electromagnetic contactor 25 can be properly maintained and managed. Moreover, since the logical operation circuit 31 for calculating the opening / closing frequency data ΣN as described above is originally provided for the protection operation and the control operation by the control center, it is a configuration for accumulating the data. There is no risk of complication. A second embodiment of the present invention is shown in FIGS. 3 and 4, and only parts different from the first embodiment will be described below.

In FIG. 3, a detection circuit 41 provided in place of the detection circuit 40 in the first embodiment has a function as a voltage detection means in addition to a function as a current detection means similar to the above-mentioned detection circuit 40. Control bus 2
The main circuit voltage ΔE at the timing when the electromagnetic contactor 25 is cut off is taken in based on the voltage stop signal input timing from the auxiliary contact 25a and the voltage signal given between 9a and 29b, and the main circuit voltage ΔE and the main circuit voltage ΔE The circuit current ΔI is applied to the logical operation circuit 31.

Here, in general, between the main circuit voltage and the contact life at the time of the breaking operation of the electromagnetic contactor, as shown in FIG. 4, the contact life becomes constant when the main circuit current is constant. The relation given as a function of the main circuit voltage (F2 = f (x
2)) exists (the X axis and the Y axis in FIG. 4 are logarithmic scales).

The logical operation circuit 31 calculates the added value Lx based on the equation (1) based on the above relationship (F2 = f (x2)) between the contact life and the main circuit voltage ΔE. ,
A correction is performed such that the added value Lx increases as the main circuit voltage ΔE increases, and the corrected added value is accumulated in the opening / closing frequency data ΣN.

Therefore, according to this embodiment, the electromagnetic contactor 2
When the main circuit voltage ΔE at the time of the breaking operation of No. 5 is high, that is, when the breaking operation has a large influence on the life of the electromagnetic contactor 25, the added value Lx is corrected to be large. The opening / closing frequency data ΣN displayed on 39 is more reliable as data for determining the actual durable opening / closing frequency of the electromagnetic contactor 25.

Furthermore, in the second embodiment, the correction of the added value Lx can reflect the level of the power factor. That is, FIG. 5 shows a third embodiment of the present invention in which the second embodiment is modified. In FIG. 5, the determination circuit 42 calculates the power factor Δφ based on the main circuit current ΔI and the main circuit voltage ΔE detected by the detection circuit 41, and the calculated power factor Δφ is the main circuit current ΔI and It is given to the logical operation circuit 31 together with the main circuit voltage ΔE.

Generally, as shown in FIG. 6, the main circuit current and the main circuit voltage are kept constant between the power factor of the main circuit and the contact life during the breaking operation of the electromagnetic contactor. The contact life is given as a function of power factor (F
3 = f (x3)) exists (the X axis and the Y axis in FIG. 6 are in logarithmic scale).

The logical operation circuit 31 calculates the added value Lx based on the equation (1) based on the above relationship (F3 = f (x3)) between the contact life and the power factor Δφ. , The lower the power factor Δφ, the larger the added value Lx is corrected, and the added value after the correction is used as the opening / closing frequency data Σ.
Accumulate in N.

Therefore, according to the present embodiment, the electromagnetic contactor 2
When the power factor Δφ during the shutoff operation of 5 is low, that is,
When the shutoff operation has a large influence on the life of the electromagnetic contactor 25, the addition value Lx is corrected so as to be further increased. Therefore, the opening / closing frequency data ΣN displayed on the display unit 39 is the electromagnetic contactor 25. The data for determining the actual number of times of endurance opening / closing is more reliable.

[0035]

As is apparent from the above description, according to the present invention, when the life of the electromagnetic contactor provided to open and close the main circuit is monitored, the logical operation circuit originally determines the life of the electromagnetic contactor. It is possible to perform accurately with a simple configuration using, and it is possible to achieve an accurate effect of maintenance management.

[Brief description of drawings]

FIG. 1 is a schematic electric circuit configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the main circuit current and contact life used in the same example.

FIG. 3 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a main circuit voltage and contact life used in the same embodiment.

FIG. 5 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 6 is a characteristic diagram showing the relationship between the power factor and contact life used in the same example.

FIG. 7 is a view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

In the drawing, 21 is a power bus, 22 is an electric motor (load), and 23
Is a main circuit, 24 is a circuit breaker for wiring (main circuit device), 25 is an electromagnetic contactor (main circuit device), 25a is an auxiliary contact, 25b
Is an operating coil, 26 is a current converter (main circuit device), 2
7 is a zero-phase current transformer (main circuit device), 30 is a control unit, 31 is a logical operation circuit, 32 is a start operation switch (operation device), 33 is a stop operation switch (operation device), and 39 is a display unit. , 40 and 41 are detection circuits (current detection means), 42
Indicates a determination circuit.

Claims (3)

[Claims] 1. An input device provided with a main circuit device such as an electromagnetic contactor interposed in a main circuit between a power bus and a load, and an operating device for operating the load. In a load control device provided with a logical operation circuit that performs control of the main circuit device according to the magnitude of a signal and a main circuit current based on a pre-stored control program, the main circuit during a breaking operation of the electromagnetic contactor A current detection unit for detecting a current is provided, and the main circuit current detected by the current detection unit and a preset breaking current and endurance switching are performed every time the electromagnetic operation circuit performs the breaking operation of the electromagnetic contactor. A function that calculates an added value that increases as the main circuit current increases based on a logical expression indicating the relationship of the number of times and sequentially accumulates the added value, and a device that displays the accumulated result on the display unit. Load control apparatus characterized by the addition of. 2. A voltage detection means for detecting a main circuit voltage during a breaking operation of the electromagnetic contactor is provided, and the logical operation circuit detects a main circuit voltage detected by the voltage detection means during an operation of the added value. The load control apparatus according to claim 1, wherein the load control apparatus is configured to perform a correction such that the higher the value is, the larger the added value is. 3. The logical operation circuit calculates a power factor based on a main circuit current detected by the current detection unit and a main circuit voltage detected by the voltage detection unit, and at the time of calculating the added value, The load control device according to claim 2, wherein the load control device is configured to perform a correction such that the added value increases as the power factor decreases.