JPS583334B2 - Thermal response trip device for circuit breakers and breakers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal tripping device for a three-pole type circuit breaker, and in particular to a thermal tripping device for a circuit breaker equipped with a closed jacket made of an insulating material, which has an open-phase protection function. The purpose is to provide the following.

A circuit breaker equipped with a closing jacket made of an insulating material, which is the background of this invention, has three pairs of contacts that can be moved to open and close relative to each other within the closing jacket, and an opening/closing mechanism for opening and closing these contacts. This type of circuit breaker is called a wiring circuit breaker and a motor protection circuit breaker, which houses a mechanism and a tripping device that responds to overload current so as to act on the latch of the opening/closing mechanism and release it. The device is a tripping device that acts on the latch of the opening/closing mechanism to trip the opening/closing mechanism, and detects overcurrent by heating and bending the bimetal provided at each pole using Joule heat caused by the overload current of each pole. , circuit breakers equipped with thermal response trip devices that trip the circuit breaker even when the bimetal of one of the poles bends, opening all three poles at the same time, are commonly used. Unlike when only one phase is blown out, all three poles are opened at the same time, so the open phase protection function is considered unnecessary, and conventionally there has been no circuit breaker that has an open phase protection function.

However, in this invention, one phase of the electric wire connected to the circuit breaker is often disconnected in the middle, or an open phase occurs due to an error in connection. Focusing on the fact that variable equipment burns out due to open-phase power distribution, the thermal response trip device installed in the circuit breaker operates at a current slightly lower than the current-carrying trip setting value. A thermal response tripping device for a circuit breaker that also has an open-phase protection function by opening the circuit breaker has been developed to expand the protection range.

The drawings show an embodiment of the thermally responsive trip device for a circuit breaker according to the present invention, and in FIGS. 1 and 2, the closing envelope of the circuit breaker includes a mold base 1 made of an insulating material and a mold cover. 2, an opening/closing mechanism (not shown)
A trip lever 3 is provided which is operatively connected to the trip lever 3, and a latch pin 4a of a latch 4 is releasably engaged at the tip of the trip lever 3.

A tripper 5 consisting of a three-pole interlocking plate is integrally attached to the latch 4, and a shaft 6 is rotatably supported by a fixed frame γ.

A return spring 8 of the trip bar 5 is installed between the fixed frame 7 and a spring mounting plate 9 provided on the latch 4, and constantly applies a clockwise rotational force to the latch 4 and the tripper 5.

The bimetal 10 is provided for each pole as a thermally responsive tripping element of the overcurrent tripping device, and is mounted on the mold base 10 substrate so that its curved direction is parallel to the pole arrangement direction. It is connected to the intermediate connection terminal 11 at the connecting plate 12 and to the contactor member by a conductive member (not shown), and its upper free end is connected to the conductive terminal 14 via the flexible conductor 13. 6 In addition, the U-shaped fixed core 15 of the electromagnet device for instantaneous tripping has a bimetal 1 of each pole inside this fixed core 15.
0 is provided so as to penetrate therethrough, and the fixed core 1 is further provided so as to pass through it.
A movable core 16 is provided corresponding to the movable core 16, and when the fixed core 15 is attracted, the lower end of the tripper 5 is actuated to rotate the tripper 5 counterclockwise.

Further, an adjustment screw 17 is attached to the free end of the bimetal 10, and an enlarged head 17a is attached to one end of this adjustment screw 17.
is provided.

The auxiliary tripper 18 is rotatably supported at its end by a shaft 19 provided on the fixed frame 7 in parallel to the rotation axis 6 of the tripper 50, and each of the auxiliary trippers 18 is supported so as to face the tripper 5 that interlocks the three poles. It is extremely extended.

This auxiliary tripper 18 is provided with adjustment screw through holes 20 for each pole as shown in FIG.
By inserting the enlarged head 17a of the adjustment screw 17 into the enlarged hole 20a of 0 and then fitting the neck of the adjustment screw 17 into the through hole 20b, the adjustment screw 17 can move freely in the direction of the tip of the enlarged head, but the auxiliary trip The auxiliary tripper 18 engages with the enlarged head 17a to prevent the parr 18 from rotating in the same direction.

Near the other end of the auxiliary tripper 18, there is an auxiliary lever 2 separated for each pole at a portion corresponding to the adjustment screw 17 of each pole.
1 is attached so that the enlarged head 17a of the adjustment screw 1T is sandwiched between an auxiliary tripper 18 and an auxiliary lever 21.

This auxiliary lever 21 is formed in a stepped shape as shown in FIGS. 6 and 7, and has a protruding piece 2lb at the upper end corresponding to the tripper 5, and a bent protruding piece 21a at the lower end. It is inserted into a mounting hole provided in the auxiliary tripper 18 and is engaged with the auxiliary tripper 18, and is always kept biased toward the auxiliary tripper 18 by elastic means consisting of an elastic plate 22 fixed to the free end of the auxiliary tripper 18. ing.

In the thermally responsive tripping device for a circuit breaker of the present invention configured in this manner, when a normal three-phase balanced overload current flows through the bimetal 10, as shown in FIG. The tips of the enlarged heads 17a of the adjustment screws 17 of each pole press the auxiliary lever 21, so that
The auxiliary tripper 18, which is engaged and connected to the lower end of the lever 21, is also rotated together with the shaft 19 as a fulcrum, and the auxiliary lever 21
Since the projection piece 21b at the upper end serves as the operating point and rotates the tripper 5 counterclockwise, the engagement between the latch pin 4a and the trip lever 3 is released, and the trip lever 3 is rotated counterclockwise and activated. The circuit breaker is tripped and opened by collapsing the opening/closing mechanism that is connected to the circuit breaker.

Next, when one of the three phases is energized in a non-energized state, the bimetal 10 at the pole of the non-energized phase does not bend as shown in FIG. 17a
engages with the auxiliary tripper 18 and the auxiliary tripper 1
8 is restrained from moving, and the other energized phase has two poles of bimetal 10.
is curved, and the tip of the enlarged head 17a of the adjustment screw 17 is rotated by the auxiliary lever 21 against the elastic plate 22, using the engagement point with the auxiliary tripper 18 as a rotational fulcrum, as shown by the dotted line in FIG. This causes the trip lever 5 to rotate and operate to open the circuit breaker to the tripped state.

Since the minimum trip current that should be activated during a phase loss is lower than that during a three-phase balanced overload, the amount of displacement of the bimetal 10 is small during a three-phase balanced overload; The amount of displacement is small.

Therefore, even if the amount of displacement of the bimetal 10 is different, it is necessary to apply the same rotation angle to the tripper 5 to trip the circuit breaker.

For this purpose, an auxiliary tripper 1 is used as shown in FIG.
80 Operating point X of the adjustment screw 17 from the axis 19 that forms the rotation fulcrum
a, the distance from the operating point X of the adjustment screw 17 to the rotational fulcrum Y of the auxiliary lever 21 is b, and the distance from the operating point A of the auxiliary lever 21 to the rotational fulcrum 19 of the auxiliary tripper 180 is C. If the displacement of the bimetal during a three-phase balanced overload is D, then the displacement at point A is reduced by the auxiliary tripper 18 and the auxiliary lever 21, and if the displacement of the bimetal during an open phase load is D, then the displacement at point A is reduced. Since the displacement D'8 of auxiliary tripper 18 and point Y are fixed, the movement of D, is therefore amplified.

Also, D is the displacement at point A required for the circuit breaker to trip.

Then, D'=D. Or, if D'8=Do, the bimetallic metal is assumed to operate at a current of 1.25 times the rated current in a three-phase balanced overload, and 0.9 times the rated current in an open phase load because it will trip if D'8=Do. If the amount of displacement is proportional to the square of the current, then D=KX1.25"=1.5625K (K is a constant of proportionality)... However, K is a proportionality constant)・
...(5) Now, by substituting (4) and (5) into equation (3), we get a, b
, c are selected so as to satisfy equation (7) by changing the respective dimensions, and the tripping operation can be performed under predetermined conditions during a Sanwa balanced overload and an open phase.

This invention supports the bimetal 10 that curves in response to overcurrent as described above on the substrate 1 of each pole so that the bending direction is parallel to the respective pole arrangement direction, and the bimetal 10 expands by curving the bimetal 10. The tripper 5 that spans each pole is rotatably supported around a shaft 6 perpendicular to the direction, and the latch pin 4a of the latch 4 is removed from the trip lever 3 to release the opening/closing mechanism and trip. In a three-pole circuit breaker, the tripper 5
An auxiliary tripper 18 for each pole is supported around another shaft 19 arranged parallel to the axis 6 of the auxiliary tripper 18, one end of which is engaged with and supported on the free end side of the auxiliary tripper 18, and the other end of which is engaged with the free end of the auxiliary tripper 18. 50 An auxiliary lever 21 provided separately for each pole so as to correspond to a position A away from the rotation fulcrum 6, an elastic stage 22 that biases the auxiliary lever 21 toward the auxiliary tripper 18 side, and a bimetal 10 The adjustment screw 17 has an enlarged dog head 17a attached to the free end side of the adjustment screw 1T, and the adjustment screw 17 passes through the auxiliary tripper 18, and the tip of the adjustment screw 1T acts as the rotation fulcrum of the auxiliary lever 21. Corresponding to the intermediate position of the point, the enlarged head 17a is disposed between the auxiliary tripper 18 and the auxiliary lever 21 so that it can engage with the auxiliary tripper 18, and for normal three-phase balanced overload current. Due to the curvature of the bimetal 10 of each pole, the tip of the enlarged head 17a of the adjusting screw 17 is displaced in the same way for all three poles, presses the auxiliary lever 21, rotates together with the auxiliary tripper 18, and adjusts the tripper. 5 to bring the circuit breaker into a trip state, and when energizing one of the three phases in a non-energized state, the adjustment screw 17 of the bimetal 10 is enlarged so that the pole of the non-energized phase does not shift. While the head 17a engages with the auxiliary tripper 18 and restrains the auxiliary tripper 18 in the engaged position, the bimetal 10 of the conductive electrode of the other phase moves the auxiliary lever 21 using the engagement point with the auxiliary tripper 18 as a fulcrum. By rotating against the elastic means 22, the tripper 5 is rotated to lead the circuit breaker to the trip state, so the configuration is simple and it can be used in the event of a three-phase balanced overload or an open phase. A thermally responsive tripping device for a circuit breaker that satisfies the desired tripping operation is obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the thermal response tripping device for a circuit breaker according to the present invention. FIG. 1 is a sectional side view of the main part of the circuit breaker, and FIG. 2 is a sectional view of the main part of the circuit breaker. Top view, Figure 3 is an explanatory diagram showing the tripping operation due to three-phase balanced overload current, Figure 4 is an explanatory diagram showing the tripping operation in an open phase state, and Figure 5 is an auxiliary lever attached to the auxiliary trip bar. FIGS. 6 and 7 are front views and side views of the auxiliary lever, and FIG. 8 is an explanatory view showing the amount of displacement of each part due to the amount of displacement of the bimetal. In the figure, 3: trip lever, 4: latch, 4a: latch pin, 5: trip bar, 7: fixed frame, 8: spring, 10: bimetal, 15: fixed core, 16:
Movable core, 17: Adjustment screw, 17a: Enlarged head, 18
: Auxiliary trip bar, 20: Through hole, 20a: Enlarged hole,
20b: Through slot, 21: Auxiliary lever, 21a, 21b
: Projection piece, 22: Elastic plate.

Claims (1)

[Claims] 1 A bimetal that bends in response to overcurrent is supported on the substrate of each pole so that the direction of bending is parallel to the direction of each pole arrangement, and the bimetal's curvature causes the axis in the direction perpendicular to the bimetal's elongation direction to become a fulcrum. In a three-pole circuit breaker equipped with an insulating jacket, the trip bar is rotatably supported across each pole, and the trip bar is rotated to release the latch and release the opening/closing mechanism, leading to the trip state. An auxiliary trip bar that spans each pole is supported on another shaft that is arranged parallel to the rotation axis of An auxiliary lever is provided separately for each pole to correspond to a more distant position, an elastic means for biasing this auxiliary lever toward the auxiliary trip bar, and an enlarged tip attached to the free end of the bimetal. an adjustment screw having a head, the adjustment screw passing through the auxiliary trip bar, and the enlarged head tip of the adjustment screw being located between the pivot point and the actuation point of the auxiliary lever; The enlarged head of the auxiliary trip bar is arranged between the auxiliary trip bar and the auxiliary lever so that it can be engaged with the auxiliary trip bar, and for normal three-phase balanced overload current, the tip of the adjustment screw is Displaces all three poles, rotates the auxiliary trip bar and the auxiliary lever together, rotates the trip bar, and brings the circuit breaker into the trip state, causing any one of the three phases to become de-energized. When energization is applied in this state, the enlarged head of the adjustment screw of the bimetal of the pole of the non-energized phase restrains the auxiliary trip bar, and the bimetal of the other pole rotates the respective auxiliary lever against the elastic means to trip. A thermal response tripping device for a circuit breaker, characterized by rotating a bar to lead the circuit breaker to a trip state.