JP4980116B2 - Overload relay - Google Patents

Description

  The present invention relates to an overload relay, and in particular, self-power feeding that detects a load current by means of current detection means such as a CT (Current Transformer) or a Hall element, and supplies operation power for a detection circuit from the load current. Type overload relay.

  Overload relays are commonly used in the field of industrial machinery and equipment as a means for protecting electrical equipment (eg, motors, hereinafter referred to as “loads”) from damage caused by overheating or excessive current. Is an electrical switch. This overload relay is generally used as an electromagnetic switch combined with another relay called an electromagnetic contactor that does not have a current detection function, and this electromagnetic switch is connected to a power supply source and a load. The load to be protected is protected by being inserted into the connecting electric circuit. That is, when an overload condition is detected by the overload relay, a coil (trip coil) provided in the overload relay is energized, and the contact portion in the overload relay is opened by the excitation action of the energized trip coil. When the excitation of the coil of the magnetic contactor connected in series with the contact part is released, the contact of the magnetic contactor is activated and opened, and as a result, the power supply to the load is cut off and the load Damage is prevented.

  For overload relays, thermal overload relays with bimetal elements and resistive heaters, and control devices such as microcomputers perform switch control based on load currents detected by current detection means such as CT and Hall elements There are electronic overload relays. In particular, the latter electronic overload relay has attracted attention as an overload relay having low power and excellent controllability, and there are many products.

  By the way, in the conventional typical thermal overload relay and electronic overload relay, the power supply to itself is cut off when the electromagnetic switch is opened, so the recovery operation must be relied on manually. There wasn't. In addition, there is a type of product that drives an overload relay with a separate power supply, but when using such a product, a separate power supply must be prepared in addition to the power supply system that drives the load. Because it leads to an increase in equipment costs, it was never used for anything other than a special purpose.

  On the other hand, in recent industrial facilities, a large number of industrial machines are operating and their operation is automated. To restore the overloaded relay that tripped, the worker visited the site every time it tripd and restored it. The work has led to a significant reduction in work efficiency. Therefore, the user side has desired a self-feeding type that automatically performs a recovery operation after a predetermined time of the trip operation.

  As a document disclosing a technique applied to a self-feeding type protective relay that does not need to supply control power in a circuit breaker tripping power supply device, for example, there is Patent Document 1 below. In this patent document 1, it is going to implement | achieve the use of an electronic type protective relay also in an electric room without a battery.

Japanese Utility Model Publication No. 7-16334

  However, in a self-powered overload relay, the energy obtained as an operating power source for the circuit is small, so that it is necessary to store sufficient energy in the capacitor to perform the trip operation. On the other hand, since the capacitor is also a life product, the trip operation is inevitably affected by the deterioration of the capacitor. In particular, when the capacitor deteriorates, the energy stored in the capacitor decreases and the trip operation cannot be performed, the load to be protected is damaged. There was also a concern that this could lead to a fire in the equipment. It was no exaggeration to say that this is the reason why self-powered electronic overload relays are not widely used.

  The present invention has been made in view of the above, and an object thereof is to provide an overload relay capable of reliably protecting a load to be protected connected to a self-powered electronic overload relay. To do.

  In order to solve the above-described problems and achieve the object, an overload relay according to the present invention includes a first capacitor that acts as a trip power source, a trip coil that is excited by accumulated charges in the first capacitor, A first energizing means for energizing the trip coil, a second capacitor acting as a trip auxiliary power source, a current energizing direction when the second capacitor excites the trip coil, and the first capacitor The electric current flows when the coil is excited so as to be in the same direction as that of the second capacitor and the trip coil, and flows through an electric path connecting the power supply source and the load. A controller comprising an overload detection unit for monitoring the magnitude of current and a trip power supply deterioration diagnosis unit for diagnosing the deterioration state of the first capacitor. The trip power supply deterioration diagnosis unit determines a deterioration state of the first capacitor when the first capacitor is discharged, and the controller determines that the first capacitor is deteriorated. In this case, the second current-carrying means is turned on to discharge the second capacitor additionally.

  According to the overload relay of the present invention, when the first capacitor is discharged, the deterioration state of the first capacitor is determined, and when it is determined that the first capacitor is deteriorated, the second energization means , And the second capacitor is additionally discharged, so that the load to be protected connected to the self-powered electronic overload relay can be reliably stopped.

  Hereinafter, preferred embodiments of an overload relay according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by embodiment shown below.

Embodiment 1 FIG.
(Configuration of overload relay)
FIG. 1 is a diagram illustrating the configuration of the overload relay according to the first embodiment of the present invention. The overload relay shown in the figure includes a controller 10 that is built in the overload relay and controls the overall operation of the overload relay. Capacitors 21 and 31, a trip coil 22, Each element of the switching elements 23 and 32 is provided. In addition, the controller 10 includes each component of a trip power supply deterioration diagnosis unit 11, a trip determination unit 12, a trip operation unit 13, and an overload detection unit 14. The capacitor 21 acts as a trip power source for operating the trip coil 22, and the capacitor 31 acts as a power source for a reset coil (not shown), and also serves as an auxiliary power source for operating the trip coil 22. Works.

(Overload relay connection configuration)
Next, each element constituting the overload relay shown in FIG. 1 and a connection configuration between each element and each functional unit of the controller 10 will be described.

  In FIG. 1, one end of a capacitor (first capacitor) 21 constituting a trip power supply is connected to one end of a trip coil 22, and the other end is grounded. The other end of the trip coil 22 is connected to the drain of the switching element 23 which is, for example, an N-type FET, and the source of the switching element 23 is grounded. On the other hand, one end of the capacitor (second capacitor) 31 is connected to the source of the switching element 32 which is a P-type FET, for example, and the other end is grounded. The drain of the switching element 32 is connected to one end of the trip coil 22.

  The connection with the controller 10 is as follows. Trip power supply deterioration diagnosis unit 11 is connected to one end of capacitor 21, and trip operation unit 13 is connected to the gates of switching elements 23 and 32.

  The configuration shown in FIG. 1 shows an example, and various modifications can be made without departing from the spirit of the present invention. For example, in the configuration shown in FIG. 1, the switching elements 23 and 32 are arranged on the low side (low potential side (ground side in the configuration of FIG. 1)), but these switching elements are arranged on the high side (high potential side). ) May be arranged. In each switching, for example, in the configuration shown in FIG. 1, the switching element 23 uses an N-type FET and the switching element 32 uses a P-type FET, but each type is arbitrary. However, from the viewpoint of easily configuring the overload relay, it is of course preferable to select a suitable type according to the position where each switching element is arranged.

(Operation of overload relay)
Next, the operation of the overload relay shown in FIG. 1 will be described. In FIG. 1, the overload detection unit 14 monitors the current detected by current detection means (not shown) such as a CT or a Hall element. The trip determination unit 12 determines an overcurrent or an open phase based on the monitoring result of the overload detection unit 14. When the trip determination unit 12 determines that an overcurrent or a phase loss state has occurred, the trip operation unit 13 turns on the switching element 23 to energize the trip coil 22. For energization of the trip coil 22, the electric charge accumulated in the capacitor 21 acting as a trip power source is used.

  Trip power supply deterioration diagnosis unit 11 detects the voltage at one end of capacitor 21 acting as a trip power supply, and diagnoses the deterioration state of capacitor 21. For example, the deterioration state may be diagnosed by using a conventional method utilizing the relationship between the discharge time and the voltage difference when the accumulated charge of the capacitor 21 is discharged to the trip coil 22. The trip operation unit 13 turns on the switching element 23 according to the diagnosis result of the trip power supply deterioration diagnosis unit 11 and further turns on the switching element 32. That is, in this embodiment, in addition to the accumulated charge of the capacitor 21 as the first capacitor, the accumulated charge of the capacitor 31 as the second capacitor is also used for energizing the trip coil 22. Whether or not the capacitor 31 is used for energizing the trip coil 22 can be determined by measuring the voltage value of the capacitor 21 at the start of the trip operation.

  In the above control, since the electric charge accumulated in both the capacitor 21 and the capacitor 31 is used for energizing the trip coil 22, the deterioration of the capacitor 21 has progressed, and the accumulated electric charge amount has decreased. Also, the trip coil 22 can be operated.

  In the above control, by measuring the voltage value of the capacitor 21 before the trip operation is started, a reliable trip operation can be performed by supplying a sufficient current due to an overcurrent described later.

  When a self-powered overload relay is used, power can be supplied from the load to be protected, so that a sufficient sufficient current can be supplied to the capacitor 21 in an overcurrent state. For this reason, even when the voltage value of the capacitor 21 is not sufficient at the start of the trip operation, sufficient energy (accumulated charge) can be obtained by supplying the sufficient current for a predetermined time. It can be carried out.

  As described above, according to the overload relay of this embodiment, when the capacitor 21 is discharged, the deterioration state of the capacitor 21 is determined, and when it is determined that the capacitor 21 is deteriorated, the switching element 32 is switched. Since the capacitor 31 is additionally discharged by conducting, the load to be protected connected to the self-powered electronic overload relay can be stopped reliably.

  In addition, according to the overload relay of this embodiment, since the deterioration diagnosis is performed at the time of the operation when the trip operation is performed, the capacitor deterioration diagnosis for the direct trip operation is performed. Accurate deterioration diagnosis is possible.

  Further, in the overload relay according to this embodiment, since a discharge circuit or the like added for diagnosing the deterioration of the capacitor is not required, the number of parts can be reduced and the configuration can be simplified.

  In the overload relay of this embodiment, only the capacitor 21 is discharged when the terminal voltage of the capacitor 21 is equal to or higher than a predetermined value, and when the terminal voltage of the capacitor 21 is equal to or lower than the predetermined value, the capacitor 21 and the capacitor 21 are discharged. Therefore, the voltage value required during trip driving can be ascertained reliably, and the probability of trip failure can be reduced.

  Further, in the overload relay of this embodiment, the deterioration diagnosis of the capacitor 21 is performed again after a predetermined time has elapsed after the discharge of the capacitor 21 is suspended, and when the terminal voltage of the capacitor 21 is equal to or higher than the predetermined value, the capacitor 21 Since both the capacitor 31 and the capacitor 31 can be discharged, the probability of trip failure can be reduced by waiting for power supply to the capacitor due to overcurrent to the load.

Embodiment 2. FIG.
(Configuration of overload relay)
FIG. 2 is a diagram illustrating the configuration of the overload relay according to the second embodiment of the present invention. The overload relay according to the second embodiment shown in FIG. 2 is the same as that of the overload relay according to the first embodiment shown in FIG. Hall element) 41 is provided. In the configuration of FIG. 2, the current detection element 41 is arranged on the low side (low potential side) of the switching element 23, but may be arranged on an arbitrary path through which the current to the trip coil 22 flows. it can. Further, configurations other than those described above are the same as or equivalent to those of the first embodiment, and the same reference numerals are given to the respective components and description thereof will be omitted.

(Operation of overload relay)
Next, the operation of the overload relay shown in FIG. 2 will be described. In FIG. 2, the current flowing through the trip coil 22 is detected by the current detection element 41 and transmitted to the discharge current detection unit 42. That is, in the overload relay of this embodiment, the current flowing through the trip coil 22 is directly detected, and the deterioration state of the capacitor 21 is diagnosed based on the detected value. The subsequent operation is the same as in the first embodiment, and a description thereof is omitted.

  According to the above control, since the value of the current flowing through the trip coil is directly detected, it is possible to contribute to the improvement of diagnosis accuracy with respect to the deterioration of the capacitor.

  As described above, according to the overload relay of this embodiment, the deterioration state of the first capacitor directly detects the current flowing through the trip coil using the current detection element 41. In addition to the effect of the first embodiment, it is possible to directly determine the magnitude of coil excitation, and in addition to the effect of the first embodiment, it is possible to easily and reliably determine whether or not a trip is necessary.

  As described above, the overload relay according to the present invention is useful for a self-powered overload relay.

It is a figure which shows the structure of the overload relay concerning Embodiment 1 of this invention. It is a figure which shows the structure of the overload relay concerning Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Controller 11 Trip power supply deterioration diagnosis part 12 Trip determination part 13 Trip operation part 14 Overload detection part 21,31 Capacitor 22 Trip coil 23,32 Switching element 41 Current detection element 42 Discharge current detection part

Claims (6)

A first capacitor acting as a trip power source;
A trip coil excited by the stored charge of the first capacitor;
First energization means for energizing the trip coil;
A second capacitor acting as a trip auxiliary power supply;
The second capacitor and the second capacitor such that the current energizing direction when the second capacitor excites the trip coil and the current energizing direction when the first capacitor excites the trip coil are the same direction. A second energizing means interposed between the trip coil,
A controller comprising an overload detection unit that monitors the magnitude of the current flowing in the electric path connecting the power supply source and the load, and a trip power supply deterioration diagnosis unit that diagnoses the deterioration state of the first capacitor;
With
The trip power supply deterioration diagnosis unit determines the deterioration state of the first capacitor when the first capacitor is discharged,
The overload relay, wherein when the controller determines that the first capacitor is deteriorated, the controller causes the second energizing means to conduct and additionally discharge the second capacitor.   The overload relay according to claim 1, wherein the deterioration state of the first capacitor is determined based on a voltage value of the first capacitor. Current detection means for detecting a current flowing in the trip coil is provided;
The overload relay according to claim 1, wherein the deterioration state of the first capacitor is determined based on a detection value of the current detection means. A first capacitor acting as a trip power source;
A trip coil excited by the stored charge of the first capacitor;
First energization means for energizing the trip coil;
A second capacitor acting as a trip auxiliary power supply;
The second capacitor and the second capacitor such that the current energizing direction when the second capacitor excites the trip coil and the current energizing direction when the first capacitor excites the trip coil are the same direction. A second energizing means interposed between the trip coil,
An overload detector for monitoring the magnitude of the current flowing in the electric path connecting the power supply source and the load, and a trip power supply deterioration diagnosis unit for diagnosing the deterioration state of the first capacitor based on the terminal voltage of the first capacitor. A controller comprising:
With
The controller is
When the terminal voltage of the first capacitor is equal to or higher than a predetermined value, only the first capacitor is discharged. When the terminal voltage of the first capacitor is lower than a predetermined value, the first capacitor and the first capacitor An overload relay characterized by discharging both of the second capacitors. A first capacitor acting as a trip power source;
A trip coil excited by the stored charge of the first capacitor;
First energization means for energizing the trip coil;
A second capacitor acting as a trip auxiliary power supply;
The second capacitor and the second capacitor such that the current energizing direction when the second capacitor excites the trip coil and the current energizing direction when the first capacitor excites the trip coil are the same direction. A second energizing means interposed between the trip coil,
An overload detector for monitoring the magnitude of the current flowing in the electric path connecting the power supply source and the load, and a trip power supply deterioration diagnosis unit for diagnosing the deterioration state of the first capacitor based on the terminal voltage of the first capacitor. A controller comprising:
With
The controller is
When the terminal voltage of the first capacitor is equal to or higher than a predetermined value, only the first capacitor is discharged. When the terminal voltage of the first capacitor is lower than a predetermined value, the first capacitor and the first capacitor An overload relay, wherein the discharge of the second capacitor is suspended. The trip power supply deterioration diagnosis unit performs deterioration diagnosis of the first capacitor again after a predetermined time has elapsed after holding the discharge of the first capacitor.
The controller is
The overload relay according to claim 5, wherein when the terminal voltage of the first capacitor is equal to or higher than a predetermined value, both the first capacitor and the second capacitor are discharged.

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