JPH07245044A - Automatic trip device of breaker - Google Patents

Abstract

PURPOSE:To make the circuit structure of a trip coil simple, and its manufacture easy. CONSTITUTION:The main circuit currents of breakers 31 to 33 are transformed by current transformers 41 to 43, and three fuses 91 to 93 are provided to the secondary sides of the current transformers. Furthermore, three excessive voltage suppressing elements 161 to 163 to suppress an excessive current owing to the fusing of a fuse are provided, and a trip coil 17 in which a plunger of operating a breaker composed of three electromagnetic coils 171 to 173 and a single plunger rod 174 in a bobbin is formed. And in an excessive current generating condition, an AC current is let flow to the trip coil by the voltage limited by an excessive voltage suppressing element after the fuse is melted, a trip hook 15 is rotated by this current, and the breaker 32 and the like are cut off en bloc by the pulling force of an energy accumulating spring 11. By the AC driving of the trip coil, a rectifier in the DC driving is made unnecessary. The trip coil is composed to a single trip coil. The coil can be composed to have a high impedance by suppressing the excessive voltage by the excessive voltage suppressing element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic trip device for a circuit breaker, and more particularly to an automatic trip device for extracting a main circuit current of a circuit breaker from a current transformer to excite a trip coil.

[0002]

2. Description of the Related Art An automatic trip device for a circuit breaker is installed, for example, in a ring main unit (single line diagram) shown in FIG.

The line side of the load switch 1 with ground is connected to the disconnector 2
And a load (not shown) is connected through a series circuit of the time-limited circuit breaker 3. As an automatic trip device for the circuit breaker 3, a current transformer 4 that transforms the main circuit current of the circuit breaker 3 is provided, and this current is used as an input of the overcurrent relay 5 and the zero-phase relay 6, and a ground fault on the load side or In the event of a short circuit, the trip coil 7 of the circuit breaker 3 is excited by the operation of the relay 5 or 6. Reference numeral 8 is an external power supply that supplies the power required for the relay and the trip coil 7.

This automatic trip device requires an external power source 8 and also expensive relays 5 and 6. As a solution to these problems, as shown in FIG. 3, a trip circuit using a secondary current of a current transformer as a power source and a fuse as a time element is known.

In the figure, the main circuit currents of the three-phase (R, S, T) circuit breakers 3 _{1 to} 3 ₃ are respectively transformed by the current transformers 4 ₁ to 4 ₃ , and the two current transformers are transformed. Fuse 9 _{1 in the} next circuit
˜9 ₃ and trip coils 5 _{1 to} 5 ₃ are connected in parallel.

In this configuration, the current transformer 4 ₁ is normally used.
To 4 ₃ of the secondary current flows in the fuse 91 _to 93 _3, trip coil 5 ₁ to 5 ₃ are short-circuited. When the earth絡又the load side short circuit fault occurs, the current transformer 41 _{to 3} secondary current increases, the fuse 9 ₁ to 9 ₃ is the time - blown according fusing characteristics, this blown The secondary current of the current transformer flows through the trip coils 5 _{1 to} 5 ₃ and the circuit breakers 3 ₁ to ₃ 3 perform a breaking operation.

When the load side accident is a three-phase short circuit, all trip coils 5 _{1 to} 5 ₃ are excited, and in the case of a ground fault, the trip coil of the ground fault phase is excited and the current of the fault phase is cut off. To be done.

FIG. 4 shows another trip circuit diagram. FIG rectifies the secondary current of the current transformer ₄₁ to ₃ to another phase in the rectifier circuit 10, a case where a single DC trip coil 5 is provided on the DC side. The two fuses 9 ₁ , 9 ₂ short-circuit the secondary circuit of the current transformer with each other.

The operation in the case of this conventional example is almost the same as that in the case of FIG. 3, and the AC input of the rectifier circuit 10 is short-circuited by the fuses 9 ₁ and 9 _{2 to} prevent the circuit breakers 3 _{1 to} 3 ₃ from tripping. One or both of the fuses 9 ₁ and 9 ₂ are blown by an electric current, the trip coil 5 is excited by direct current, and all the circuit breakers 3 ₁
Shut off 3 to ₃ at once.

FIG. 5 is a schematic view of the circuit breaker operating mechanism. The circuit breaker 3 is shown as a vacuum interrupter, and the movable contact 3b is biased by the accumulating spring 11 on its trip side with respect to the fixed contact 3a.

The operation rod 12 has a main shaft 13 as a center of rotation and one end engages with an operation end of the movable contact 3b, and the other end engages with a trip hook 15 via a roller follower 14. The trip hook 15 is rotationally driven by the plunger mechanism of the trip coil 5.

In this structure, the main shaft 13 is operated in the clockwise direction by a mechanism (not shown), and the operating rod 12 pushes the movable contact 3b toward the fixed contact 3a, and the closing operation of the circuit breaker 3 is obtained. At this time, the roller follower 14
Engages with the trip hook 15 to maintain the closed state of the circuit breaker 3, and the energy storage spring 11 stores the energy in the tensioned state.

In this state, when the trip coil 5 is excited, the protrusion of the plunger rod disengages the trip hook 15 from the roller follower 14,
The movable contact 3b is pulled out by the driving force of the energy storage spring 11 to disconnect the circuit breaker 3.

FIG. 6 shows three trip coils 5 _{1 to} 5 _3.
The provided shows the positional relationship of the trip hook 15 and trip coil 5 ₁ to 5 ₃ of the circuit arrangement of FIG. 3, either by the excitation of a single trip coil 5 ₁ to 5 _3, circuit breaker 3 ₁ three-phase
Shut off 3 to ₃ at once.

[0015]

In the circuit of FIG. 3, the conventional automatic trip device requires three trip coils and fuses in order to use the AC current of the current transformer as the exciting current of the trip coil as it is. The circuit becomes complicated and expensive.

In this respect, in the configuration of FIG. 4, one trip coil and two fuses are sufficient by rectifying by the rectifier circuit. However, the rectifier circuit 10 requires eight diodes, and has the same problem in cost as in the former case.

In both cases, it is necessary to make the trip coil have a low impedance to keep the secondary side of the current transformer close to a short-circuited state, and thus the coil is formed with a small number of turns and a conductor having a large diameter. Make it difficult to make.

It is an object of the present invention to provide an automatic trip device which has a simple trip coil circuit configuration and is easy to manufacture.

[0019]

In order to solve the above-mentioned problems, the present invention transforms the main circuit current of a circuit breaker with a current transformer,
In an automatic trip device for a circuit breaker, which operates the operating mechanism of the circuit breaker by exciting the trip coil using this modified current as a power source, three current transformers that respectively transform the main circuit currents of the three-phase circuit breaker, Three fuses, each of which is connected in parallel to the secondary side of each of the current transformers and has a predetermined current-time characteristic to blow out, and three fuses of which are connected in parallel to the secondary side of each of the current transformers, respectively. A plunger for circuit breaker operation is configured by having three overvoltage suppressing elements for suppressing overvoltage, three electromagnetic coils and one plunger rod in one bobbin, and the three electromagnetic coils are connected to the two current transformers. Trip coil connected to the next side,
It is characterized by having.

[0020]

The trip coil has three windings and one plunger rod, and the overvoltage suppressing element is provided in parallel with the fuse to drive the trip coil with an alternating current, thereby eliminating the need for a rectifier. Use only one trip coil.

Further, the coil can be configured to have a high impedance by suppressing the overvoltage by the overvoltage suppressing element, and the trip coil can be configured to have a high number of windings and a conducting wire having a small diameter, which facilitates its manufacture.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an apparatus showing one embodiment of the present invention.

A fuse 9 is provided in each of the current transformers 4 ₁ to 4 _3.
A parallel circuit of _{1 to} 9 ₃ and the overvoltage suppressing elements 16 _{1 to} 16 ₃ is connected. The overvoltage suppressing elements 16 _{1 to} 16 ₃ are, for example, Zener diodes or nonlinear resistors.

The trip coil 17 has three bobbins.
An electromagnetic coil is formed by winding two coils 17 _{1 to} 17 ₃ , and a plunger rod 17 ₄ is provided at the center of the bobbin. This plunger rod 17 ₄ has a trip hook 1
5 is pushed out and engaged.

The coils 17 _{1 to} 17 ₃ are connected in parallel with the fuses 9 _{1 to} 9 ₃ and the overvoltage suppressing elements 16 _{1 to} 16 ₃ to the secondary circuits of the current transformers 4 ₁ to 4 ₃ . These coils 1
The number of turns of 7 _{1 to} 17 ₃ is designed so as to have a relatively high impedance.

In this embodiment, the current transformer 4 ₁ is normally operated.
To 4 ₃ of the current is low, the secondary current is circulated through the fuse 91 _to 93 _3.

Here, when a ground fault or a short circuit occurs in the load connected to the circuit breakers 3 ₁ to _{3 3} , the secondary current of the current transformers 4 ₁ to 4 ₃ increases, and the fuses 9 _{1 to} 9 _{3 become} 1 One or all will blow out with a time delay according to its current-time characteristic.

As a result, the secondary current of the current transformers 4 ₁ to 4 ₃ is limited to a constant voltage determined by the overvoltage suppressing elements 16 _{1 to} 16 ₃ and flows into one or all of the coils 17 _{1 to} 17 ₃ , the plunger rod 17 ₄ rotates the trip hook 15 protrudes by the current, interrupting the operation of each phase of the circuit breaker shown in circuit breaker 3.

Therefore, in this embodiment, as the structure from the current transformer to the trip coil, one trip coil 17, three fuses and an overvoltage suppressing element may be provided, and it is possible to configure with a small number of circuit elements.

Further, since the overvoltage is suppressed by the overvoltage suppressing element, the trip coil can be made to have a relatively high impedance, and a conductor coil having a relatively small diameter can be used to make a large number of turns of the trip coil, which facilitates its manufacture. .

In the embodiment, the circuit breaker and its operating mechanism can be replaced with those of other systems to obtain the same effect.

[0032]

As described above, according to the present invention, the secondary circuit of the current transformer is constituted by the fuse, the overvoltage suppressing element, and one trip coil having three coils wound around one bobbin. , Has the following effects.

(1) Since the trip coil is excited by using the transformer current of the current transformer as a power source, an external power source becomes unnecessary.

(2) Since the trip coil has three windings and one plunger rod, the fuse is provided with an overvoltage suppressing element in parallel, and the trip coil is driven by an alternating current, a rectifier is not required. At the same time, only one trip coil is required, which simplifies the configuration.

(3) The coil can be made to have a high impedance by suppressing the overvoltage by the overvoltage suppressing element, and the trip coil can be made to have a high number of windings and a conductor having a small diameter, which facilitates its manufacture.

[Brief description of drawings]

FIG. 1 is a device configuration diagram showing an embodiment of the present invention.

FIG. 2 is a single-line diagram of a ring main unit.

FIG. 3 is a conventional trip circuit diagram.

FIG. 4 is a conventional trip circuit diagram.

FIG. 5 is a schematic diagram of a circuit breaker opening operation.

FIG. 6 is another operating mechanism diagram.

[Explanation of symbols]

3 ₁ 3 ₃ Circuit breaker 4 ₁ 4 ₃ Current transformer 5 ₁ 5 ₃ Trip coil 9 ₁ 9 ₃ Fuse 10 Rectifier circuit 11 Energy storage spring 15 Trip hook 16 ₁ 16 ₃ … Overvoltage suppression element 17… Trip coil

Claims (1)

[Claims] 1. A main circuit current of a circuit breaker is transformed by a current transformer,
In an automatic trip device for a circuit breaker, which operates an operating mechanism of the circuit breaker by exciting a trip coil using the modified current as a power source, three current transformers that respectively transform the main circuit currents of the three-phase circuit breaker, Three fuses that are respectively connected in parallel to the secondary side of each of the current transformers and have a predetermined current-time characteristic to blow out, and three fuses that are respectively connected in parallel to the secondary side of each of the current transformers due to the blowout of the fuses A plunger for circuit breaker operation is configured with three overvoltage suppressing elements for suppressing overvoltage, three electromagnetic coils and one plunger rod on one bobbin, and these three electromagnetic coils are connected to the two current transformers. An automatic trip device for a circuit breaker, which is provided with a trip coil connected to each of the secondary sides.