JP2983803B2 - Earth leakage cutoff device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth leakage interrupting device for interrupting a circuit when an earth leakage occurs in a main power supply line and an auxiliary power supply line drawn from a single generator.

[0002]

2. Description of the Related Art Conventionally, an engine generator has been used in outdoor construction and the like, and a three-phase main power line and a single-phase auxiliary power line are drawn from the engine generator. A large-capacity load mainly for construction is connected to the main power line, and a small-capacity load such as lighting is connected to the auxiliary power line.

[0003] An earth leakage interrupting device is provided to shut off a circuit when an earth leakage occurs in the main power supply line or the auxiliary power supply line. As shown in FIG. 2, this earth leakage breaker grounds a ground line 52 connected to a neutral point of a star-connected output winding 50 of a generator via a capacitor 54, and connects the ground line 52 to a main zero. It is a primary winding of the phase current transformer 56.

The main zero-phase current transformer 56 is connected to a main ground-fault detector 58, and when the main ground-fault detector 58 detects an induced current flowing through the main zero-phase current transformer 56, it is connected to the output winding 50. The main power supply lines 60, 61, and 62 are configured to be cut off by opening the contacts of the main circuit breaker 64 interposed between the connected three-phase main power supply lines 60, 61, and 62.

Further, an auxiliary zero-phase current transformer 70 having a single-phase auxiliary power supply line 66, 68 connected to one phase of the output winding 50, for example, U-phase, is provided. An auxiliary ground fault detector 72 is connected to the flower 70. Auxiliary zero-phase current transformer 7
When the auxiliary ground fault detector 72 detects an induced current flowing through the auxiliary power supply line 66, the contact of the auxiliary circuit breaker 74 interposed between the auxiliary power supply lines 66, 68 is opened to cut off the auxiliary power supply lines 66, 68. Was.

[0006]

However, in such a conventional device, when a leakage occurs in one auxiliary power supply line 66, an induced current flows in the auxiliary zero-phase current transformer 70, and the auxiliary ground fault detector 72 And the auxiliary power supply lines 66 and 68 are cut off by the auxiliary circuit breaker 74. At the same time, a leakage current also flows through the U-phase of the output winding 50 and the ground wire 52, so that an induced current flows through the main zero-phase current transformer 56, and the main ground fault detector 58 detects this, and There is a problem that the main circuit breaker 64 also cuts off the main power supply lines 60, 61, 62 even though no electric leakage occurs on the lines 60, 61, 62 side.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problem, distinguishing between a main power supply line and an auxiliary power supply line,
An object of the present invention is to provide a leakage detection device that can shut off only a side where a leakage has occurred.

[0008]

In order to achieve the above object, the present invention has the following structure as means for solving the problems. That is, the main power is disconnected to the three-phase main power supply line connected to the star-connected output winding of the generator, and to the single-phase auxiliary power supply line connected to one phase of the star-connected output winding. The earth leakage wire connected to the neutral point of the star connection is used as the primary winding of the main zero-phase current transformer, and the auxiliary power supply wire is supplemented. The primary winding of the zero-phase current transformer, and a main ground fault detector that opens the main circuit breaker by induced current is connected to the secondary winding of the main zero-phase current transformer to form a main closed circuit. The two ends of a shunt in which an auxiliary ground fault detector that opens the auxiliary circuit breaker by an induced current in the secondary winding of the auxiliary zero-phase current transformer is connected in series are connected to both ends of the main zero-phase current transformer. Induced current generated in the secondary winding of the main zero-phase current transformer and the shunt when leakage current occurs on both sides and the auxiliary power line side Cancel, configuration fault interrupter device, characterized in that the main ground fault detection device is connected to not opening operation of the main circuit breaker is it.

[0009]

In the earth leakage breaker having the above construction, when an earth leakage occurs on the main power supply line side, a leakage current flows through the ground line, and an induced current is induced in the secondary winding of the main zero-phase current transformer. The main ground fault detector detects this, opens the main circuit breaker, and cuts off the main power line.

When leakage occurs on the auxiliary power supply line side, an induced current is induced in the secondary winding of the auxiliary zero-phase current transformer, and the auxiliary ground fault detector detects this, opens the auxiliary circuit breaker, Cut off the power line. Along with this, a leakage current also flows through the ground wire, and an induced current is induced in the secondary winding of the main zero-phase current transformer. The induced current in the secondary winding of the main zero-phase current transformer and the induced current in the shunt cancel each other to prevent the main ground fault detector from opening the main circuit breaker.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram of a leakage interrupting device according to one embodiment of the present invention. Reference numeral 1 denotes a star-connected output winding of the generator, which is driven by an engine (not shown). Main power lines 2 to 4 are connected to the U, V, and W phases of the output winding 1, respectively, and a main circuit breaker 6 is interposed between the main power lines 2 to 4. The main circuit breaker 6 includes contacts 8 to 10 corresponding to the main power lines 2 to 4, and contacts 8 to 1.
By opening 0, the main power supply lines 2 to 4 can be cut off.

Further, one phase of the output winding 1, in this embodiment U
The single-phase auxiliary power lines 14 and 15 are connected to the phase and the neutral point 12 of the output winding 1, respectively.
An auxiliary circuit breaker 16 is interposed in 15. The auxiliary circuit breaker 16 is connected to the contacts 18,
The auxiliary power supply lines 14 and 15 can be cut off by opening the contacts 18 and 19.

One end of a ground line 20 is connected to the neutral point 12, and a capacitor 22 in this embodiment is connected to the ground line 20.
And the other end of the ground line 20 is grounded.
Note that a resistor may be used instead of the capacitor 22. A main zero-phase current transformer 24 having the ground wire 20 as a primary winding is provided, and a secondary winding 24a of the main zero-phase current transformer 24 is connected to a main ground fault detector 26 to form a main closed circuit. 27 are formed. When a leakage current flows through the ground wire 20, the main ground fault detector 26 responds to the secondary winding 24 a of the main zero-phase current transformer 24.
The main ground fault detector 26 detects the induced current, excites the trip coil 26a, opens the contacts 8 to 10, and cuts off the main power lines 2 to 4.

An auxiliary zero-phase current transformer 28 having auxiliary power lines 14 and 15 as primary windings is provided, and one end of a secondary winding 28a of the auxiliary zero-phase current transformer 28 is connected to an auxiliary ground fault detection. Vessel 30
Are connected in series to form a shunt 31. Both ends of the shunt 31 are connected to both ends of the main zero-phase current transformer 24. Further, the shunt 31 is connected such that induced currents generated in the secondary winding 24a of the main zero-phase current transformer 24 and the shunt 31 cancel each other.

When a leakage occurs and a difference occurs between the currents of the auxiliary power supply lines 14 and 15, an induced current is induced in the secondary winding 28a of the auxiliary zero-phase current transformer 28, and an auxiliary ground fault is detected. The detector 30 detects this, excites the trip coil 30a, opens the contacts 18, 19, and cuts off the auxiliary power lines 14, 15.

Next, the operation of the above-described electric leakage breaker of this embodiment will be described. First, a generator is rotated by the engine to generate power, and three-phase AC power is supplied from the output winding 1 to the main power supply lines 2 to 4. In addition, single-phase AC power is supplied to the auxiliary power lines 14 and 15.

When leakage occurs on the main power supply lines 2 to 4, a leakage current flows through the ground line 20, and an induced current I ₀₁ is induced in the secondary winding 24 a of the main zero-phase current transformer 24. This induced current I
₀₁ is detected by the main ground fault detector 26, the trip coil 2
6a is excited, the contacts 8 to 10 of the main circuit breaker 6 are opened, and the main power supply lines 2 to 4 are cut off.

When a leakage occurs on the auxiliary power supply lines 14 and 15, an induced current _I02 is induced in the secondary winding 28a of the auxiliary zero-phase current transformer 28. Auxiliary ground fault can 30 has detected induced current I ₀₂ flowing through the secondary winding 28a of the auxiliary ZCT 28, and energizes the tripping coil 30a, the contact 18, 19 of the auxiliary circuit breaker 16 Open, auxiliary power line 14,1
Block 5

[0019] At this time, also the leakage current flows to the ground line 20, the main ZCT induced currents I ₀₁ to the secondary winding 24a of 24 is induced. Secondary winding 2 of auxiliary zero-phase current transformer 28
The induced current I ₀₂ of 8a, the main ZCT 24 secondary winding 2
The induced current I _{01 of} FIG. 4a cancels each other out, and the current I ₀₃ (= I ₀₁ −I ₀₂ ) flowing through the main ground fault detector 26 becomes zero, so that the tripping coil 26a is not excited and Lines 2-4 are not interrupted.

As described above, according to the earth leakage breaker of this embodiment, the earth leakage on the main power lines 2 to 4 and the auxiliary power lines 14 and 1
The side on which the leakage has occurred can be cut off by distinguishing the leakage on the 5th side. As described above, the present invention is not limited to such embodiments at all, and can be implemented in various modes without departing from the gist of the present invention.

[0021]

As described in detail above, the earth leakage breaker of the present invention can distinguish between earth leakage on the main power line side and earth leakage on the auxiliary power line side and shut off the side where the earth leakage has occurred. It works.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an earth leakage cutoff device as one embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional earth leakage breaker.

[Explanation of symbols]

1,50 ... Output winding 2-4,60 ... Main power supply line
6, 64: Main circuit breaker 12: Neutral point 14, 15, 66: Auxiliary power line 16, 74: Auxiliary circuit breaker 20, 52: Ground line 24, 56: Main zero-phase current transformer 26, 58: Main area Fault detector 27 ... Main closed circuit 28,70 ... Auxiliary zero-phase current transformer 30,72 ... Auxiliary ground fault detector 31 ... Shunt

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02H 3/32-3/52 H02H 7/06 H02P 9/00-9/48

Claims (1)

(57) [Claims] 1. A three-phase main power supply line connected to a star-connected output winding of a generator and a single-phase auxiliary power supply line connected to one phase of the star-connected output winding. In the earth leakage breaker in which the main circuit breaker and the auxiliary circuit breaker are interposed, a ground wire connected to a neutral point of the star connection is used as a primary winding of a main zero-phase current transformer, and the auxiliary power supply is A main ground fault detector for opening the main circuit breaker by induced current to the secondary winding of the main zero-phase current transformer; The two ends of a shunt in which an auxiliary ground fault detector for opening the auxiliary circuit breaker by an induced current is connected to the secondary winding of the auxiliary zero phase current transformer in series are connected to the main zero phase transformer. Connected to both ends of the current transformer, and when a leakage occurs on the auxiliary power line side, the leakage occurs on the secondary winding and the shunt of the main zero-phase current transformer. An earth leakage breaker, wherein the induced currents cancel each other, and the main ground fault detector is connected so as not to open the main circuit breaker.