JPH05176445A - Three-phase short circuit suppressor - Google Patents

Abstract

PURPOSE:To sharply reduce thyristor switch elements. CONSTITUTION:Thyristor switch elements Sh11-Sh13 are connected to three-phase distribution lines U, V, and W, with the polarities directed in one direction. The thyristor switch elements Sh11-Sh13 are ignited by the gate signals form a controller CNL. The controller CNL sends out a gate signal when the current on load side from a current transformer CT becomes a preset value or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase short-circuit suppressing device for suppressing arc short-circuit current on the load side in a three-phase distribution line.

[0002]

2. Description of the Related Art As shown in FIG. 2, three-phase distribution lines U, V,
In W, it is assumed that two or more ground faults occur in the load-side distribution line due to a lightning strike, which causes a two-phase or three-phase line-to-line short circuit accident. In this case, unless the accident current is promptly reduced, the distribution line may be broken due to the arc current. In order to prevent this, three-phase distribution lines U, V,
Thyristor switch element S connected in anti-parallel to the power supply side of W
The h ₁ ~Sh ₆ connected between the phases, to several cycles fired at a gate signal from these thyristor switching element Sh ₁ ~Sh ₆ controller CNL. The current transformer C is provided in the control device CNL.
The load side current detected at T is supplied. Control device CNL
When the load current exceeds a preset value (for example, a ground fault of two or more lines occurs), a gate signal is given to the thyristor switch elements Sh ₁ to Sh ₆ to apply the gate signal to the thyristor switch elements Sh _{1 to} Sh ₆ as described above. Ignition Sh ₆ for several cycles,
Reduce the line voltage. This extinguishes the arc voltage. After that, the thyristor switch elements Sh _{1 to} Sh ₆
Turns off and the circuit recovers.

[0003]

As shown in FIG. 2, the conventional three-phase short-circuit suppressing device requires six circuits of three-phase distribution lines U, V, W for thyristor switching elements Sh _{1 to} Sh ₆ connected in antiparallel. there were. In particular, in a 6.6 KV class distribution line, a plurality of thyristor switch elements connected in series must be connected in antiparallel, which causes a problem that the number of thyristor switch elements becomes extremely large.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a three-phase short-circuit suppressing device in which the number of thyristor switch elements can be significantly reduced.

[0005]

In order to achieve the above object, the present invention detects a short circuit arc current on the load side by connecting a thyristor switch element between the phases in one direction in a three-phase distribution line. At this time, the thyristor switch elements between the respective phases are simultaneously fired.

[0006]

When the arc current is generated on the load side, this current is detected and the thyristor switch element is ignited. As a result, no current flows from the power supply side to the load side, and the arc current is suppressed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In Figure 1, U, V, W in three phases distribution line, connects the thyristor switching element Sh ₁₁ ~Sh ₁₃ toward the three-phase distribution line U, V, between each phase of the W in one direction. These thyristor switch elements Sh _{11 to} Sh ₁₃ are control devices CN.
It is fired by the gate signal from L. The controller CNL is configured to send a gate signal when the load-side current supplied from the current transformer CT exceeds a preset value.

In the embodiment configured as described above,
If a two-phase or three-phase line short-circuit accident occurs on the load side distribution line, an arc short-circuit current flows at that point. This current is detected by the current transformer CT and supplied to the controller CNL. Then the gate signal from the control unit CNL is given to the thyristor switch element Sh ₁₁ ~Sh _13, thyristor switching element Sh ₁₁ ~Sh ₁₃ is ignited at the same time. For this reason, the line voltage is changed to the thyristor switches Sh _{11 to} Sh ₁₃
Short-circuited by. As a result, the arc short-circuit current on the load side disappears. Then, the thyristor switch element Sh ₁₁
When the gate signal ～Sh ₁₃ is not supplied, the thyristor switching element Sh ₁₁ ~Sh ₁₃ circuit turned off is restored to a sound state. A plurality of thyristor switch elements between each phase are connected in series for use.

[0009]

As described above, according to the present invention,
Since the thyristor switch elements are connected to each phase in one direction, the number of elements can be significantly reduced.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

U, V, W ... three-phase distribution lines, Sh ₁₁ ~Sh ₁₃ ... thyristor switching element, CNL ... controller, CT ... current transformer.

Claims (1)

[Claims] 1. In a three-phase distribution line, a thyristor switch element is connected between the phases in one direction, and when an arc short-circuit current on the load side is detected, the thyristor switch elements between the phases are simultaneously ignited. The three-phase short-circuit suppressing device characterized in that