GB2175447A

GB2175447A - Interlock mechanism for switchgear

Info

Publication number: GB2175447A
Application number: GB08608633A
Authority: GB
Inventors: Minoru Nakahata
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1985-04-10
Filing date: 1986-04-09
Publication date: 1986-11-26
Also published as: GB8608633D0; DE3607435C2; JPS61237326A; DE3607435A1; GB2175447B

Abstract

A switch gear is constituted compatible for disconnecting a voltage as well as breaking current, and also for effectively interrupting abnormal current, by combining a vacuum, interrupter 1 and a disconnecting switch 4 connected in series, and further linking the vacuum interrupter and the disconnecting switch with an interlock mechanism that opens the vacuum interrupter after the disconnecting switch has been opened. The interlock includes pivoted levers that trip a latch of the vacuum interrupter. <IMAGE>

Description

SPECIFICATION Switch gear FIELD OF THE INVENTION AND RELATED ART STATEMENT 1. FIELD OF THE INVENTION The present invention relates generally to a switch gear and particularly to a switch gear for interrupting both an electric current and an applied voltage.

2. DESCRIPTION OF THE RELATED ART In a switch gear for switching both a current and a voltage of a prior arts, a disconnecting switch which does not have the function for switching a current has been used to switch a voltage, and a load break switch or a contactor has been used to switch a current.

Furthermore, in order to interrupt a shortcircuit current, a circuit breaker is used, and a load break switch or a combination of a contactor and a fuse is also used since the function of these combination is almost the same as a load break switch.

As mentioned above, the switch gear for switching the current and the voltage is formed by the combination of the plural switching apparatus which are suitable for each required function in a characteristic and an economical aspect, because the switching apparatus having all required functions in one body is very expensive to be adopted in usual use. In the above-mentioned case, for example, a load break switch or a contactor is combined with a fuse, however, the cost of frequent exchanging of the fuse is expensive, since the fuse melts at the each operation of the circuit breaker. Furthermore, since the circuit breaker cannot open the circuit which is applied with a high voltage, a disconnecting switch must be combined with the circuit breaker.However the cost of the apparatus will become expensive and the large space for the arrangement is required when such disconnecting switch is used.

OBJECT AND SUMMARY OF THE INVENTION The switch gear in the present invention comprises: a vacuum interrupter and a disconnecting switch connected in series, a first operation mechanism for charging a driving force during a closing process of the vacuum interrupter, a second operation mechanism for driving the disconnecting switch, interlock means for opening the vacuum interrupter with a predetermined delay time from an opening of the disconnecting switch in an interlock operation, detecting means for detecting an excessive value of a current of a circuit connected thereto, trigger means to be operated by detection of the excessive value of a current on the detecting means, a latch for holding the driving force of the first operation mechanism.

When the switch gear is opened, the vacuum interrupter is opened rapidly by the discharging force which was charged on the closing process of the vacuum interrupter.

The open of the switch gear if operated by firstly opening the disconnecting switch and after a lapse of a predetermined period opening the vacuum interrupter.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a drawing showing a block diagram of a switch gear.

FIG.2 is a timing chart showing the operation of the switch gear in overcurrent state.

FIG.3 is a timing chart showing the operation of the switch gear in short-circuited state.

FIG.4 is a schematic diagram of an example of a combination of two operation mechanisms and an interlock mechanism.

FIG.5 is a flow chart showing close operation of the switch gear in the present invention.

FIG.6 is a flow chart showing open operation of the switch gear in the present invention.

FIG.7 is a flow chart showing emergency open operation of the switch gear in the present invention.

DESCRIPTION OF THE PREFERRED EMBODI MENTS A preferred embodiment of a switch gear in the present invention is shown in FIG. 1. A vacuum interrupter 1 comprises two terminals 2a and 3a which are connected to contacts 2 and 3, respectively. A fixed contact 5 of a disconnecting switch 4 is connected with the terminal 3a. The disconnecting switch 4 also has a transfer contact 6, which is connected to a line 7 at a fulcrum 6a, which enables the contact 6 to contact the fixed contact 5. An operation mechanism 8 is operated by hand and closes the contacts 2, 3 of the vacuum interrupter. When a lever 14 is moved to an arrow direction, the contact 2 touches the contact 3, and simultaneously a spring 21 (shown in FIG.4) which is provided in the operation mechanism 8 is charged by the moving of the lever 14.The transfer contact 6 of the disconnecting switch 4 is driven by an operation mechanism 9. The operation mechanism 9, for example, is driven by the charged energy of a spring or a force of a magnet. A current transformer 11 detects a current of the line 7, and output of the current transformer 11 is applied to an overcurrent relay 10.

When an overcurrent flows jn the line 7, the overcurrent relay 10 is operated by the output of the current transformer 11, and a trigger mechanism 15 drives operation mechanism 8.

An interlock mechanism 12 controls a timing of operation between the operation mechanism 9 of the disconnecting switch 4 and the operation mechanism 8 of the vacuum interrupter 1, in a manner that when this switch gear opens, at first the transfer contact 6 opens, then the vacuum interrupter 1 opens after lapse of a predetermined period therefrom. An example of a combination of the operation mechanism 8, the operation mechanism 9 and the interlock mechanism 12 is shown in FIG.4. In the example, when a shaft 20 is rotated in a direction of an arrow B by an operation of the lever 14, a linkage 26 rotates to the same direction as the rotation of the shaft 20. The vacuum interrupter 1 is closed by the rotation of the shaft 20 through a link member not shown in FIG.4.A spring 21 which is hooked between a pin 22 fixed on the operation mechanism 8 and a pin 23 fixed on the linkage 26 is compressed by the rotation of the linkage 26. A guide 24 is rotated in a direction of an arrow C by the rotation of the linkage 26, and is finally hooked by a latch 25 and is held. On the other hand, a driving lever 28 is rotated clockwise by driving means not shown in FIG.4 after the above operation of guide 24 and the disconnecting switch 4 is closed and a spring 29 which is hooked between pins 30 and 31 is compressed. A trigger mechanism 15 is an electromagnet.

The operation of this embodiment is elucidated in the following: The timing chart showing the operation of this embodiment is shown in FIGs. 2 and 3.

In FlGs.2 and 3, waves A and B show an open state Jnd a close state of the vacuum interrupter 1, and high levels show the close state and low levels show the open state.

The timing of the close state and the open state of the disconnecting switch 4 is shown by the wave B of FIG.2. The operation sequence when the switch gear closes is as follows. At first, the lever 14 of the operation mechanism 8 is moved by hand, and thereby the vacuum inter;upter 1 is closed. The spring which is provided in the operation mechanism 8 is charged by the above-mentioned motion of the lever 14, and this state is shown by a time "a" in FIG.2A.

The guide 24 is rotated and is held by the latch 25 by the motion of the lever 14. In the next place, the disconnecting switch 4 is closed at time "b" by the operation mechanism 9 which is driven by a driving means not shown in FIG.4, for example, an electromagnet or a charged spring energy.

The driving lever 28 is rotated clockwise by the driving means and is held by the interlock mechinism 12 at the pin 33. This state is shown by wave B in FIG.2. As a result, a pair of the contacts 2, 3 and a pair of the contacts 5, 6 are closed and the current flows in the line 7.

In order to open this switch gear, at first the disconnecting switch 4 is operated by hand at the point of time "c" in FIG.2B, thereby the operation mechanism 9 is operated. The intnerlock 12 is kicked down by the pin 33. A lever 27 is pulled to rightward by rotation of the interlock 12, and the latch 25 is rotated clockwise. When the latch 25 disconnects itself from the guide 24, the guide 24 rotate clockwise, and the linkage 26 is rotated counter-clockwise at a high speed by the force of the spring 21 which was changed by the lever 14 during the closing process of the vacuum interrupter 1. The timing of this action is shown "d" in FIG.2B. The time difference t, between the times of the two waves A and B in FIG.2 shows the delay time which is given by the interlock mechanism 12.

On the other hand, in case where an overcurrent or a large current due to a short-circuit flops in line 7, the current transformer 11 detects those excessive currents, and an overcurrent relay 10 is operated by the detected signal. The trigger mechanism operated by the overcurrent relay 10, and a moving shaft 16 of the trigger mechanism 15 moves to rightward and pushes the latch 25. As a result, the latch 25 disconnect from the guide 24 and the guide 24 rotates clockwise. Hence the linkage 26 rotates counter-clockwise, and the contacts 2, 3 of the vacuum interrupter 1 are opened at high speed by the discharging force of the spring 21, which is charged by the operation of the lever 14. The point of time in FIG.3A shows this timing. In the above-mentioned case, the disconnecting switch 4 does not move in the interlock relation with the vacuum interrupter 1 but keeps the closed state.The disconnecting switch 4 is made open by the manual operation of the operation mechanism 9 of the disconnecting switch 4.

This timing is shown by the point of time "f" in FIG.3B. The respective sequences of the above-mentioned operations are shown by flow charts in FIG.5, FIG.6 and FIG.7.

In the above-mentioned embodiment, the operation mechanism 8 of the vacuum interrupter 1 is operated by hand. In case of a large type switch gear, however, the operation mechanism 8 is operated by driving mechanism using such as an electric motor or a fluid pressure apparatus.

Experimental study shows that the method to directly operate the disconnecting switch 4 by hand is adaptable, and that the delay time t, between the operation of the disconnecting switch 4 and the vacuum interrupter 1 is preferably less than 2 cycles.

As mentioned above, the switch gear in the present invention is operable to interrupt both voltage and the current in case that the abnormal current flows only by a compatible switch gear which is constituted as a combination of an inexpensive manual vacuum interrupter and an inexpensive disconnecting switch. The switch gear is also advantageous in that its maintenance cost is inexpensive, since an expendable such a fuse is not necessary.

As another effect, a surge which is induced by the interruption of a normal current is suppressed by the interruption by both the vacuum interrupted the disconnecting switch connected in series.

Claims

1. A switch gear comprising: a vacuum interrupter and a disconnecting switch connected in series, a first operation mechanism for charging a driving force during a closing process of said vacuum interrupter, a second operation mechanism for driving disconnecting switch, interlock means for opening said vacuum interrupter with a predetermined delay time from an opening or the disconnecting switch in an interlock operation, detecting means for detecting an excessive value of a current of a circuit connected thereto, trigger means to be operated by detection of said excessive value of a current on said detecting means, a latch for holding said driving force of said first operation mechanism.

2. A switch gear in accordance with claim 1, wherein said first operation mechanism has a spring and a lever which is operated by hand.

3. A switch gear in accordance with claim 1, wherein said second operation mechanismm have a spring and a driving lever for driving said interlock means:

4. A switch gear in accordance with clain 1, wherein said detecting means is a current transfer mer.

5. A switch gear in accordance with claim 1, wherein said trigger means is an electromagnet.

6. A switch gear in accordance with claim 1, wherein said latch is driven by said interlock means or said trigger means:

7. A switch gear substantially as herein described with reference to any of the accompanying drawings.