WO2014156000A1

WO2014156000A1 - Ground-fault-detecting tripping unit

Info

Publication number: WO2014156000A1
Application number: PCT/JP2014/001309
Authority: WO
Inventors: 佐藤　昌弘; 稲次　崇
Original assignee: パナソニック株式会社
Priority date: 2013-03-26
Filing date: 2014-03-07
Publication date: 2014-10-02
Also published as: JP2014191909A; JP6037229B2; CN105122415A

Abstract

This ground-fault-detecting tripping unit (4), which can be externally mounted to a circuit breaker, is provided with the following: a housing (11); a load terminal that is connected to an electrical wire; a connecting terminal (7a) that is connected to a load-side terminal on the circuit breaker; a main circuit bar (7) that is provided so as to form an electrical path that connects the load terminal and the connecting terminal (7a); a ground-fault-detecting circuit that is provided on the path formed by the main circuit bar (7) and detects ground faults; and a tripping drive unit that drives the circuit breaker so as to break the circuit if the ground-fault-detecting circuit detects a ground fault. The housing (11) has the following: a first surface, on the side where the load terminal is, that has a first ventilation hole (16); and a second surface that faces the first surface and has a second ventilation hole (18). The main circuit bar (7) is located in the flow path between the first ventilation hole (16) and the second ventilation hole (18).

Description

Earth leakage detection trip unit

The present invention relates to a leakage detection trip unit that is applied to an external trip type earth leakage breaker including a circuit breaker and is externally attached to the circuit breaker.

Conventionally, an earth leakage circuit breaker that interrupts an electric circuit when an earth leakage is detected has been proposed (see, for example, Patent Document 1). Some earth leakage circuit breakers have a built-in leakage detection function in the circuit breaker, and others have a built-in leakage detection function in a device external to the circuit breaker. The latter is called an external trip type earth leakage breaker, and the device externally attached to the circuit breaker is called an earth leakage detection trip unit.

In general, a circuit breaker has a power supply terminal part on one end side and a load terminal part on the other end side, and a contact part, a trip mechanism part, and a handle for turning on and off the contact part between both terminal parts. And a mechanism part. In addition, there is also provided a grid portion that extinguishes an arc generated when the contact portion is tripped by the trip mechanism. On the other hand, the leakage detection trip unit has a connection terminal portion on one end side and a load terminal portion on the other end side, and a leakage detection circuit, a main circuit bar serving as an electric circuit, and a leakage detection signal between both terminal portions And a tripping drive unit that drives the tripping mechanism unit of the circuit breaker in response. In the external trip type earth leakage breaker, the connection terminal portion of the leakage detection trip unit is connected to the load terminal portion of the circuit breaker (hereinafter referred to as the connection terminal portion of the circuit breaker).

For example, a zero-phase current transformer (hereinafter referred to as “ZCT”) is used for detection of electric leakage by the leakage detection trip unit, and a main circuit bar is passed through this ZCT. For example, in the case of three-phase four-wire, four main circuit bars are passed through the ZCT. At the time of energization, the leakage detection circuit detects the difference between the current in the forward path and the return path passing through the ZCT. When there is no leakage, the difference is zero. However, when a leakage occurs, a difference occurs between the forward and return currents. This difference is amplified to cut off the electric circuit. One end side of the main circuit bar provided as an alternative to the electric wire forms a connection terminal portion of the leakage detection trip unit, and is fixed to the connection terminal portion of the circuit breaker with a terminal screw. The other end side of the main circuit bar is fixed to a load terminal portion of the leakage detection trip unit via a terminal plate with a terminal screw.

JP 2011-124217 A

In the external trip type earth leakage breaker, the temperature rise of the connection terminal of the circuit breaker when energized is greater than when the circuit breaker alone is energized. For this reason, the temperature rise of the cover in the vicinity of the connection terminal portion of the circuit breaker tends to increase.

An object of the present invention is to provide a leakage detection trip unit capable of suppressing a temperature rise in the vicinity of a connection terminal portion of a circuit breaker.

One aspect of the present invention is a leakage detection trip unit that can be externally attached to a circuit breaker. The leakage detection trip unit includes a housing, a load terminal connected to the electric wire, a connection terminal connected to the load-side terminal of the circuit breaker, the load terminal and the connection terminal. A main circuit bar provided as an electric circuit to be connected, a leakage detection circuit provided on the path of the main circuit bar to detect leakage, and a circuit breaking operation by driving the circuit breaker when leakage is detected by the leakage detection circuit A tripping drive unit for performing the operation, wherein the housing is provided on a side where the load terminal unit is located, and is opposed to the first surface having a first vent and the first surface. And the second surface having the second vent hole, and the main circuit bar is interposed in the flow path from the first vent hole to the second vent hole.

In one aspect, the leakage detection trip unit is further provided with a protrusion provided between the first vent and a zero-phase current transformer that constitutes the leakage detection circuit, and narrows the flow path. Also good.

In one embodiment, the housing may include a housing body that houses the main circuit bar and the leakage detection circuit, and a housing cover that closes an opening of the housing body. In this case, the first ventilation port includes a load terminal portion ventilation port provided on a surface of the housing body on which the load terminal portion is located, and the load terminal portion is located on the housing cover. And a bottom vent provided on the side surface.

In one embodiment, the main circuit bar, the load terminal portion vent and the second vent may be disposed on a line connecting.

In one embodiment, the leakage detection trip unit may further include a protrusion that is provided between the bottom vent and a zero-phase current transformer that constitutes the leakage detection circuit and narrows the flow path. .

According to the present invention, it is possible to suppress a temperature rise near the connection terminal portion of the circuit breaker.

The front view which shows the external trip type earth-leakage circuit breaker provided with the earth-leakage detection trip unit. FIG. 2 is a front view of the external trip type earth leakage breaker of FIG. 1 excluding a housing cover of the earth leakage detection trip unit. The perspective view of the earth-leakage detection trip unit except a housing | casing cover. The perspective view of a leak detection trip unit. The bottom view of a leak detection trip unit. Top view of the leakage detection trip unit. Sectional drawing of a leak detection trip unit.

Hereinafter, an embodiment of the leakage detection trip unit will be described.

Fig. 1 shows an external trip type earth leakage breaker. The earth leakage breaker generally includes a plurality (eg, four) of circuit breakers 3 and an earth leakage detection trip unit 4. Each circuit breaker 3 includes a power supply terminal portion 3a and a connection terminal portion 3b. An electric wire 1 is fixed to the power supply terminal portion 3a by a terminal screw 2. The connection terminal portion 3b is an example of a load side terminal portion. The leakage detection trip unit 4 includes a connection terminal portion 7a (see FIG. 3) and load terminal portions 4a (four in this case). An electric wire 1 is fixed to the load terminal portion 4a by a terminal screw 2. The four circuit breakers 3 are connected to each other by a connecting handle 5 as a handle mechanism. The connection handle 5 is connected to the interlock handle 6 of the leakage detection trip unit 4 and shuts off the circuit in conjunction with the operation of the interlock handle 6 when a leak is detected. The interlocking handle 6 is an example of a trip driving unit.

As shown in FIG. 2, main circuit bars 7 (four in this case) serving as electric circuits are routed inside the leakage detection trip unit 4. The tip of each main circuit bar 7 is welded to the terminal board 8. On the path of the four main circuit bars 7, a zero-phase current transformer (hereinafter referred to as ZCT) 9 is provided as a leakage detection circuit that detects leakage and generates a leakage detection signal. The interlocking handle 6 drives the circuit breaker 3 when the leakage current is detected by the ZCT 9 to perform the circuit breaking operation.

As shown in FIG. 3, one end side of the main circuit bar 7 is provided as a connection terminal portion 7a, and this connection terminal portion 7a is connected to the connection terminal portion 3b (see FIG. 1) of the circuit breaker 3 with a terminal screw 2. It is fixed. The other end side of the main circuit bar 7 is fixed to the load terminal portion 4 a of the leakage detection trip unit 4 via the terminal plate 8 with the terminal screw 2.

As shown in FIG. 4, the leakage detection trip unit 4 includes a terminal cover 10, a casing body 11, and a casing cover 12, which form a casing of the leakage detection trip unit 4. Yes. The earth leakage detection trip unit 4 includes a heat transfer member 14. The heat transfer member 14 is formed of, for example, a plate material bent into a substantially L shape. The plate material includes a first plate portion and a second plate portion. One end side of the heat transfer member 14 provided as the first plate portion is in contact with the end face 10 a of the terminal cover 10. The connection terminal portion 7 a of the main circuit bar 7 protected by the terminal cover 10 passes through the first plate portion of the heat transfer member 14. The other end side of the heat transfer member 14 provided as the second plate portion is disposed on the side surface of the housing body 11 located on the side close to the mechanical portion 13.

Further, as shown in FIG. 3, the leakage detection trip unit 4 includes an in-casing heat transfer member 15. The in-casing heat transfer member 15 is formed of, for example, a plate material bent into a substantially U shape. The

heat transfer members

14 and 15 are opposed to each other with the wall of the housing body 11 interposed therebetween.

As shown in FIG. 5, a substantially ellipse-shaped load terminal portion vent hole 16 is formed on the surface 11a of the housing body 11 provided on the side where the load terminal portion 4a is located. Further, a bottom vent 17 having the same shape as the load terminal vent 16 is also formed on the surface 12a of the housing cover 12 provided on the side where the load terminal 4a is located. When the leakage detection trip unit 4 is installed, the surfaces 11a and 12a are directed to the ground side. Thereby, air whose temperature is lower than that inside the housing can be taken into the housing from the ground side.

As shown in FIG. 6, in the housing body 11, an upper surface vent 18 having the same shape as the

vents

16 and 17 is formed on the surface 11 b opposite to the surface 11 a. The load terminal portion vent 16 and the upper vent 18 are on the same line, and the main circuit bar 7 is arranged on this line. The upper surface vent 18 can discharge the air flowing in from the ground side through the load terminal portion vent 16 and the bottom vent 17 from the inside of the housing to the outside. Thereby, the leakage detection trip unit 4 has a function of cooling the inside of the housing by ventilation. As shown in FIGS. 2 and 3, the main circuit bar 7 is interposed in the flow path from the load terminal portion vent 16 and the bottom vent 17 to the top vent 18.

As shown in FIG. 7, a projection 19 is formed on the inner side of the housing cover 12 from the portion between the interlocking handle 6 and the surface 12 a toward the housing body 11. The protrusion 19 is located between the bottom vent 17 formed on the surface 12a and the ZCT 9. The projection 19 narrows the flow path from the bottom vent 17 to the top vent 18 so that a faster airflow can be applied directly to the main circuit bar 7 than when there is no projection 19.

Next, the operation of the leakage detection trip unit 4 will be described.

The air taken into the housing from the ground side through the load terminal portion vent 16 and the bottom vent 17 flows toward the top vent 18. At this time, since the main circuit bar 7 is interposed in the flow path from the load terminal portion vent 16 and the bottom vent 17 to the top vent 18, the temperature increases as the temperature of the main circuit bar 7 increases during energization. The converted air inside the casing is released to the outside of the casing through the upper surface vent 18. In addition, since the flow path area is narrowed by the protrusions 19, an air flow having a higher flow velocity hits the main circuit bar 7, so that heat release to the outside is enhanced. As described above, the leakage detection trip unit 4 improves the cooling performance as well as the air permeability inside the housing by the cooperation of the load terminal portion vent 16, the bottom vent 17, the top vent 18, and the protrusion 19. The main circuit bar 7 is easily cooled. Therefore, even when the temperature of the connection terminal portion 7a of the main circuit bar 7 rises, the temperature rise value can be reduced by heat transfer due to ventilation.

This embodiment has the following advantages.

(1) The air inside the housing heated by the temperature rise of the main circuit bar 7 during energization due to the airflow flowing through the flow path from the load terminal portion vent 16 and the bottom vent 17 to the top vent 18 Can be discharged outside the housing. Thereby, since the heat generated in the main circuit bar 7 is dissipated and the connection terminal portion 3b of the circuit breaker 3 is cooled, an increase in temperature near the connection terminal portion 3b of the circuit breaker 3 can be suppressed.

(2) By providing the protrusion 19, the channel area becomes narrower and the flow velocity becomes faster than when the protrusion 19 is not provided. For this reason, the main circuit bar 7 is exposed to an airflow having a higher flow velocity. Therefore, the cooling effect of the main circuit bar 7 can be promoted.

(3) Heat that reaches the inside of the housing through the heat transfer member 14 and the heat transfer member 15 in the housing from the connection terminal portion 7a can be released to the outside of the housing along with the airflow.

(4) Since the temperature rise in the vicinity of the connection terminal portion 3b of the circuit breaker 3 is suppressed, it is not necessary to separately attach a cover that covers the connection terminal portion 3b. That is, it is not necessary to provide a dedicated member for lowering the temperature of the housing near the connection terminal portion 3b.

The above embodiment can be modified as follows.

The arrangement of the load terminal vent 16, the bottom vent 17, and the top vent 18 is not limited to the above embodiment. However, it is desirable that the airflow flows from the ground in the facing direction when the leakage detection trip unit 4 is installed. Thereby, air whose temperature is lower than that inside the housing can be taken in.

The shapes of the load terminal vent 16, the bottom vent 17, and the top vent 18 are not limited to the above embodiment. However, it is desirable that these vents 16 to 18 have a shape that can be easily processed.

The shape, position, angle, number, and the like of the protrusions 19 can be arbitrarily set according to the flow velocity or flow rate required for the airflow.

Claims

An earth leakage detection trip unit that can be externally attached to a circuit breaker,
A housing,
A load terminal connected to the wire;
A connection terminal portion connected to a load side terminal portion of the circuit breaker;
A main circuit bar provided as an electrical circuit connecting the load terminal portion and the connection terminal portion;
A leakage detection circuit provided on the path of the main circuit bar for detecting leakage;
A tripping drive unit that drives the circuit breaker to perform a circuit breaking operation when leakage is detected by the leakage detection circuit, and
The housing is
A first surface provided on the side where the load terminal portion is located and having a first vent;
A second surface facing the first surface and having a second vent,
A leakage detection trip unit in which the main circuit bar is interposed in a flow path from the first vent to the second vent.
The leakage detection trip unit according to claim 1, further comprising a protrusion provided between the first vent and a zero-phase current transformer constituting the leakage detection circuit and narrowing the flow path.
The housing is
A housing body that houses the main circuit bar and the leakage detection circuit;
A housing cover that closes the opening of the housing body,
The first vent is
A load terminal portion vent provided on a surface of the housing body on which the load terminal portion is located;
A bottom vent provided on a surface of the housing cover on which the load terminal portion is located,
The electric leakage detection trip unit according to claim 1.
The main circuit bar is disposed on a line connecting the load terminal portion vent and the second vent;
The leakage detection trip unit according to claim 3.
The leakage detection trip unit according to claim 3, further comprising a protrusion provided between the bottom vent and the zero-phase current transformer constituting the leakage detection circuit and narrowing the flow path.