JP3527630B2 - Electromagnetic contactor welding and pushbutton switch failure detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to welding a contact point of an electromagnetic contactor provided in a drive circuit for a driving motor for a hoist crane or the like and other loads (in the present specification). ,
Simply called "welding". ) And an apparatus for automatically detecting a failure of a push-button switch for opening and closing the electromagnetic contactor, and a failure detection device for the push-button switch. 2. Description of the Related Art In many cases, a high load and a large current are supplied to a drive circuit of a large load such as a drive motor of a hoist crane, and it is not possible to directly open and close the drive circuit manually. Because of the danger, the drive circuit is opened and closed indirectly using an electromagnetic contactor. By the way, the life time of the electromagnetic contactor varies depending on the frequency of use, the voltage supplied to the drive circuit, the value of the current, etc.,
Failure may occur even during maintenance and inspection.Especially, if the electromagnetic contactor is welded, operation with the pushbutton switch that opens and closes the electromagnetic contactor becomes impossible, causing a serious accident such as runaway of the hoist crane. Could be caused. In order to cope with this, the applicant of the present application has previously provided a load current detecting means which is disposed in a drive circuit for connecting a power supply and a load, detects a current flowing through the load and generates a load current signal, Excitation current detection means that is provided in the operation circuit of the electromagnetic contactor that opens and closes the drive circuit, detects the current flowing through the coil of the electromagnetic contactor and generates an excitation current signal, and a load current signal generated by the load current detection means and excitation. A welding detection device for an electromagnetic contactor comprising a welding detection device for an electromagnetic contactor for detecting welding of the electromagnetic contactor by comparing the exciting current signal generated by the current detecting device with the welding device has been proposed (see Japanese Utility Model Publication No. 2-10772). ). In this welding detection device for an electromagnetic contactor, the welding current detection means of the electromagnetic contactor compares a load current signal generated by the load current detection device with an excitation current signal generated by the excitation current detection device. When the load current signal is issued from the load current detection means even though the excitation current signal is not issued from the controller, it is determined that the electromagnetic contactor is welded, and the welding detection means of the electromagnetic contactor is used. By using the output signal, the main electromagnetic contactor of the drive circuit is opened to prevent a serious accident such as runaway of the hoist crane. [0005] By the way, as a case that causes a serious accident such as runaway of the hoist crane, the above-mentioned electromagnetic contactor is welded and operated by a push button switch for opening and closing the electromagnetic contactor. Push button switch that opens and closes the electromagnetic contactor, for example, when the push button return spring of the push button switch is damaged, dust or the like gets stuck in the sliding part of the push button, and the push button is locked. It is conceivable that the push button does not return when pressed down. When the push button switch is broken due to breakage of the push button return spring of the push button switch, dust being caught in the sliding portion of the push button and locking of the push button, etc., the load current signal is output from the load current detecting means. Further, since the exciting current signals are respectively emitted from the exciting current detecting means, the failure of the push button switch cannot be detected by the welding detecting device of the electromagnetic contactor described above. In order to detect a failure of the push button switch, particularly, a failure of the push button switch when the power switch is closed (when the power is turned on), a contact for an operation circuit, So-called a
In addition to the contacts, a state where the pushbutton of the pushbutton switch is restored when the power switch is closed, that is, a confirmation circuit contact for confirming that the operation circuit contact is open,
Using a so-called push-button switch provided with a contact b (see, for example, Japanese Utility Model Application Laid-Open No. 52-53374), as shown in FIG. 4, a sequence circuit having a confirmation circuit in which the b contacts are connected in series is assembled. Push button switch PB3, PB
4, at least one of the push buttons does not return,
The operation circuit contact (indicated by a circle in the figure) is closed (in this case, the confirmation circuit contact corresponding to the closed operation circuit contact (indicated by a circle in the figure) is open) so,
Even if the power switch PB1 is operated, the main electromagnetic contactor MC0
Is not closed so as to constitute a push button switch failure detecting device. However, this pushbutton switch failure detection device requires a large operating force to operate the pushbutton of the pushbutton switch because the pushbutton switch needs to be provided with a contact b, and the operability of the pushbutton switch is poor. Also,
The structure of the push button switch becomes complicated, the push button switch becomes larger, and the manufacturing cost increases. The confirmation circuit with the b contacts connected in series is prone to contact failure,
Further, since the structure of the push button switch becomes complicated, the probability of the failure of the push button switch increases, and the maintenance and inspection work increases. And so on. In addition, as a failure detecting device for a push button switch, as shown in FIGS. 5 and 6, electromagnetic contactors MC1, MC2,.
A sequence circuit having a confirmation circuit in which the b contacts of X2,... Are connected in series is assembled, and a plurality of pushbutton switches PB2,
In a state where at least one of the push buttons of PB3,... Does not return and the b contacts of the electromagnetic contactors MC1, MC2,... Or the auxiliary relays MCX1, MCX2,. The main electromagnetic contactor M
Although a device in which C0 is not closed has been proposed, in the case of this pushbutton switch failure detection device, the electromagnetic contactors MC1, MC2,.
A confirmation circuit in which the b contacts of MCX2,... Are connected in series is liable to cause a contact failure and the circuit configuration becomes complicated, so the probability of failure of the failure detection device increases, and maintenance and inspection work is performed. There were problems such as an increase. The present invention has been made in view of the above-mentioned problems of the conventional push-button switch failure detecting apparatus, and has a low failure and a stable performance for a long period of time without complicating the structure and circuit configuration of the push-button switch. An object of the present invention is to provide a welding device for an electromagnetic contactor and a failure detection device for a pushbutton switch, which can maintain the detection of the welding of the electromagnetic contactor and the failure of the pushbutton switch at the same time. [0011] In order to achieve the above object, an apparatus for detecting welding of an electromagnetic contactor and a failure of a push button switch according to the present invention comprises a drive circuit for connecting a power supply to loads M1, M2 and M3. Load current detecting means 1 disposed at R, S, T for detecting a current flowing through loads M1, M2, M3 and generating a load current signal, and each being connected in series with a power switch PB1.
Electromagnetic contactors MC1, MC for opening and closing the drive circuits R, S, T connected to the loads M1, M2, M3.
2, disposed in the operation circuit of ..., the electromagnetic contactor MC1,
MC2, an excitation current detecting means 2 for emitting excitation current signal by detecting the current flowing through the ... of the coil, the power switch P
B1 operated by driving circuits R, S, T
And a power-on detecting unit 3 for opening and closing detect and emit power on signal of the main magnetic contactor MC 0, the load current detection means 1
Load current signal emitted by the and compares the excitation current signal emitted by the excitation current detecting means 2, a welding detection means 4 of the electromagnetic contactor for detecting the welding of the electromagnetic contactor, the load current emitted by the load current detection means 1 A signal is compared with a power-on signal generated by the power-on detecting means 3 , and when the power switch PB1 is closed , the drive circuit connected to each of the loads M1, M2, M3 is driven.
Electromagnetic contactors MC1, MC2, .. for opening and closing paths R, S, T
Pushbutton switch PB3, PB4 manipulating ..., a failure detection unit 5 of the push-button switch for detecting the failure of ..., Ri Na <br/> from electromagnetic contactor of welding detection means 4 or push button switch
An output signal from the failure detecting means 5 is input to an output circuit 6.
As a result, the main circuits of the drive circuits R, S, T
A signal for opening the magnetic contactor MC0 is output . In the apparatus for detecting the welding of the electromagnetic contactor and the failure of the push button switch, the welding detecting means of the electromagnetic contactor compares the load current signal generated by the load current detecting means with the exciting current signal generated by the exciting current detecting means. Although the exciting current signal is not issued from the exciting current detecting means,
When a load current signal is issued from the load current detecting means, it is determined that the electromagnetic contactor is welded. In addition, the failure detection means of the pushbutton switch compares the load current signal generated by the load current detection means with the power-on signal generated by the power-on detection means. When a load current signal is issued from the current detecting means, it is determined that the push button switch has failed. Then, the main electromagnetic contactor of the drive circuit is opened by an output signal from the welding detection means of the electromagnetic contactor or the failure detection means of the push button switch, thereby preventing a serious accident such as runaway of the hoist crane. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 3 show an embodiment in which the apparatus for detecting the welding of an electromagnetic contactor and the failure of a push button switch according to the present invention is applied to a hoist crane. This apparatus for detecting the welding of the electromagnetic contactor and the failure of the push button switch comprises a three-phase AC power supply R, S, T, a hoisting lowering motor M1, a traversing motor M2, and a traveling motor M3 as loads. Arranged in the driving circuits R, S, T to be connected,
Load current detecting means 1 for detecting a current flowing through the loads M1, M2, M3 and generating a load current signal; and driving circuits R, S,
Excitation current detecting means disposed in the operation circuit of the electromagnetic contactors MC1, MC2,... For opening and closing T , and detecting an electric current flowing through the coils of the electromagnetic contactors MC1, MC2,. 2, a power-on detecting means 3 for detecting the opening and closing of the main electromagnetic contactor MC0 by the power switch PB1 and generating a power-on signal, a load current signal generated by the load current detecting means 1, and an exciting current generated by the exciting current detecting means 2. , The welding current detecting means 4 for detecting the welding of the electromagnetic contactors MC1, MC2,..., The load current signal generated by the load current detecting means 1 and the power supply generated by the power-on detecting means 3 A failure detection means 5 of the push button switch for detecting a failure of the push button switch PB when the power switch PB1 is closed, a welding detection means 4 of the electromagnetic contactor and a failure detection of the push button switch when the power switch PB1 is closed. The output signal from the means 5, constituting a drive circuit R, S, the output circuit 6 for outputting a signal to open the main electromagnetic contactor MC0 of T. In this case, the loads M1, M2, M3
The load current detecting means 1 which detects a current flowing through the current generator and generates a load current signal is not particularly limited, but as shown in FIG. 3, three current transformers CT1, CT2, and CTL are used. Two current transformers CT1 and CT2 are driven by a driving circuit.
The current transformer CT2 attached to the R and S phases of R, S, and T , and the conductor of the current transformer CT1 attached to the R phase is connected n times to the current transformer CT2 attached to the S phase.
Is wound around the common current transformer CTL 2n times. The conductor of the current transformer CTL is connected to a terminal provided on an apparatus main body 7 containing the exciting current detecting means 2, the welding detecting means 4 of the electromagnetic contactor, the failure detecting means 5 of the push button switch, the output circuit 6, etc. Contactor welding detection means 4
And input to the failure detection means 5 of the push button switch. Note that the load current is small and the driving circuits R and
When the diameters of the S and T conductors are small, the load current detecting means 1 is wound around the R, S and T phase conductors of the drive circuits R, S and T around one current transformer CTL. It can also be configured. In this case, the R-phase conductor is n times and the S-phase conductor is 2 times.
The conductor of the T phase is wound n times around the common current transformer CTL n times. The exciting current detecting means 2 for detecting an electric current flowing through the coils of the electromagnetic contactors MC1, MC2,... To generate an exciting current signal is introduced into the apparatus main body 7 through a terminal provided on the apparatus main body 7. Are constituted by current transformers mounted on the operation circuit of the electromagnetic contactors MC1, MC2,... And input to the welding detection means 4 of the electromagnetic contactors. Main magnetic contactor M by power switch PB1
The power-on detection means 3 for detecting the opening and closing of C0 and issuing a power-on signal is constituted by an auxiliary a contact of the main electromagnetic contactor MC0, connected to a terminal provided on the apparatus body 7, and provided with a push-button switch failure detection means 5 To be entered. Next, the operation of the apparatus for detecting the welding of the electromagnetic contactor and the failure of the push button switch will be described. The welding current detection means 4 of the electromagnetic contactor compares the load current signal generated by the load current detection means 1 with the excitation current signal generated by the excitation current detection means 2, and no excitation current signal is generated from the excitation current detection means 2. Nevertheless, when the load current signal is issued from the load current detecting means 1, it is determined that the electromagnetic contactors MC1, MC2, ... are welded.
In this case, the welding is determined by switching a dip switch (not shown) provided in the apparatus main body 7 so that the above state is continued for, for example, 0.4 seconds or more (when high-precision detection is required). , Which can be switched in two ways, that is, when it continues for 1.0 second or more. The push-button switch failure detecting means 5 compares the load current signal generated by the load current detecting means 1 with the power-on signal generated by the power-on detecting means 3. When the load current signal is immediately issued from the load current detecting means 1 immediately after the issuance, at least one of the push button switches PB3, PB4,... Does not return, and the contact for the operation circuit is closed. State, that is, the push button switches PB3, PB4,.
Judge that at least one of them has failed. In this case, the failure is determined by, for example, when the load current signal is issued from the load current detection means 1 within 0.1 second after the power-on signal is issued from the power-on detection means 3, the push button switch PB3 , PB4,... Are determined to have failed. An output signal from the welding detection means 4 of the electromagnetic contactor or the failure detection means 5 of the push button switch is input to the output circuit 6, so that the output circuit 6
A signal for opening the R, S, and T main electromagnetic contactors MC0 is output to prevent a serious accident such as runaway of the hoist crane. While the embodiment in which the apparatus for detecting the failure of the electromagnetic contactor and the push button switch of the present invention is applied to a hoist crane has been described above, the circuit configuration and the like are not limited to those of the above-described embodiment. The present invention is not limited to the hoist crane, and can be applied to drive circuits of various industrial machines having a large load. According to the apparatus for detecting welding of an electromagnetic contactor and failure of a push button switch according to the present invention, the load current signal generated by the load current detecting means and the exciting current detecting means are detected by the welding detecting means of the electromagnetic contactor. The electromagnetic contactor is welded when the load current signal is issued from the load current detection means even though the excitation current signal is not issued from the excitation current detection means. The power-on signal is output from the power-on detecting means by comparing the load current signal generated by the load current detecting means with the power-on signal generated by the power-on detecting means. When the load current signal is immediately issued from the load current detecting means after the operation, the push button switch is determined to be faulty, and the welding detecting means of the electromagnetic contactor or the push button is detected. By the output signal from the switch failure detection means,
For example, by opening the main electromagnetic contactor of the drive circuit, a serious accident such as runaway of the hoist crane can be reliably prevented. According to the welding device for the electromagnetic contactor and the failure detection device for the push-button switch, the structure and the circuit configuration of the push-button switch are not complicated, the device can be easily incorporated, and the number of mechanical operation parts is small. , Which can maintain stable performance for a long period of time due to poor contact and the like, and furthermore, means for detecting welding of the electromagnetic contactor and detecting failure of the push button switch, specifically, load Detection, which detects the welding of the electromagnetic contactor and the failure of the pushbutton switch at a low cost, in combination with the fact that the load current detecting means for detecting the current flowing through the switch and generating the load current signal can be shared. An apparatus can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an embodiment in which the welding device for an electromagnetic contactor and the failure detection device for a push button switch of the present invention are applied to a hoist crane. FIG. 2 is an explanatory view showing a main part of a device for detecting a failure of a welding and a push button switch of an electromagnetic contactor of the present invention. FIG. 3 is an explanatory diagram of load current detection means. FIG. 4 is an explanatory diagram of a conventional failure detection device for a push button switch. FIG. 5 is an explanatory diagram of a conventional failure detection device for a push button switch. FIG. 6 is an explanatory diagram of a conventional failure detection device for a push button switch. [Description of Signs] 1 Load current detecting means 2 Exciting current detecting means 3 Power-on detecting means 4 Welding detecting means of electromagnetic contactor 5 Fault detecting means of pushbutton switch 6 Output circuit 7 Main unit MC0 Main electromagnetic contactors MC1, MC2 ... Electromagnetic contactor PB1 Power switch PB3, PB4, ... Push button switch

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01H 47/00

Claims (1)

(57) [Claims 1] A load (M1, M2, M3) is connected to a drive circuit (R, S, T) for connecting a power supply and a load (M1, M2, M3) .
M2, M3) are connected in series with a load current detecting means (1) for detecting a current flowing through the power switch (PB1) and generating a load current signal, respectively.
An electromagnetic contactor (MC1, MC ) that opens and closes the drive circuit (R, S, T) connected to each of the loads (M1, M2, M3)
2, ...) and the electromagnetic contactor (MC
1, MC2, and detects the current flowing in the coil of ...) to emit the exciting current signal excitation current detecting means (2), is operated by the power switch (PB1), the driving circuit
Power-on detection means for detecting the opening and closing of the main electromagnetic contactor (MC0) interposed between (R, S, T) and issuing a power-on signal
And (3) comparing the load current signal generated by the load current detection means (1) with the excitation current signal generated by the excitation current detection means (2) to detect welding of the electromagnetic contactor. The detecting means (4) compares a load current signal generated by the load current detecting means (1) with a power-on signal generated by the power-on detecting means (3) , and compares each of the above signals when the power switch (PB1) is closed. Load (M
1, M2, M3) connected to the drive circuit (R, S,
T) Opening and closing electromagnetic contactors (MC1, MC2, ...)
A push button switch for operating the (PB3, PB4, · · ·) push button switch for detecting the failure of the fault detection means (5),
Tona is, welding detection means (4) of the electromagnetic contactor or because of a push button switch
An output signal from the fault detecting means (5) is input to an output circuit (6).
The output circuit (6) changes the driving circuit (R,
S, T) to open the main magnetic contactor (MC0)
A device for detecting the welding of an electromagnetic contactor and the failure of a push-button switch.