JPH0119312Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] This invention relates to an overcurrent detection device that is applied to remote control type circuit breakers, etc.

[Background technology]

FIG. 5 shows a conventional example. That is, the figure shows a part of the electric circuit configuration inside the circuit and disconnector, 100 is a load terminal, 101 is a short circuit detection coil, 102 is a braided copper wire covered with an insulating tube 103, 104
105 is an overcurrent detection device, 105 is a frame, 106 is a braided copper wire, and 107 is a movable contact facing a fixed contact (not shown). The overcurrent detection device 104 is constructed by bending the bimetal 108 into an L-shape, welding the base end 109 of the bimetal 108 to the frame 105, and wrapping the heater 112 around the operating part 110 via the insulating tube 111. One end of the wire is spot welded near the bent portion 113 of the bimetal 110, and the other end is welded to the braided copper wire 102, which is a so-called direct heating type.

Incidentally, the overcurrent characteristic for the power of the overcurrent detection device is set to be slower than that for the wiring so that the circuit or disconnector does not trip due to the starting current of the motor. The standard is 3 to 45 seconds at 500% _IN . In order to achieve this characteristic, the bimetal part is configured as an indirect heating type or a direct heating type.For example, the above structure is adopted for remote control type circuit breakers for 0.2KW (1.3A) to 3.7KW (15A). .

However, 5.5KW (25A) or 7.5KW (32A)
If the above structure is adopted for a relatively high capacity device, the directly heated part (the bent part 11 of the bimetal 108)
3 to frame 105) accounts for more than half of the required resistance, and bimetal 1
Since the bent portion 113 influences the amount of deflection of 08 by a little less than 50%, there was a drawback that the delay was not long enough to satisfy the overcurrent characteristics near 500% I _N. To solve this problem, the thermal time constant can be increased by reducing the directly heated part and increasing the indirectly heated part, but bimetal 1
As long as the heater 112 has an L-shape due to the structure of the circuit or disconnector, there is a limit to the wrapping method of the heater 112.

[Purpose of invention]

The purpose of this invention is to provide an overcurrent detection device which can sufficiently obtain relatively high capacity type power overcurrent characteristics and which can be achieved with a simple configuration.

[Disclosure of invention]

The overcurrent detection device of this invention consists of a bimetal that is bent into an L shape and has one end as a base end and the other end as an operating part, and a gap is provided between the bent part of the bimetal and an insulator is placed on the bimetal. and a flexible heater having one end fixed to the proximal end side and a holding piece formed at the other end slidably engaged with the operating part side. In other words, because there are fewer directly heated parts and the bent parts are indirectly heated with gaps, the
A sufficient delay around %I _N can be obtained, and the overcurrent characteristics for power use of a capacitive type can be relatively satisfied. Moreover, the structure is simpler than the conventional one.

A remote control type circuit breaker to which an embodiment of this invention is applied is shown in FIGS. 1 to 4. First, in the overcurrent detection device 1, the bimetal 2 is L-shaped with the low expansion part on the inside, and the proximal end 3, which is one end, is welded to the frame 4, and the operating part 5, which is the other end, is provided with a gap adjustment screw 6. It will be done. The bimetal 2 has an insulating tube 8 passed through the operating part 5 side and the bending part 7. The flexible heater 9 is also a belt-shaped plate that is almost the same as the bimetal 2, and is bent into an L shape along the bimetal 2, and one end 9a of the flexible heater 9 is bent into an L shape along the bimetal 2.
It is spot welded to the frame attachment part 3a of the base end part 3 of 11 connecting tongues 12 (which may be lead wires) are formed. A predetermined gap 14 is provided between the bent portion 13 and the bent portion 7 of the bimetal 2 to suppress the temperature rise of the bent portion 7 and to prevent the bending movement of the bimetal 2 from being inhibited.
In this way, the heater 9 is constructed as a completely indirect heating type, and the heater 9 is energized between the braided copper wire 11, the frame 4, and the frame attachment portion 3a of the bimetal 2. Therefore, when an overcurrent flows, the amount of heat generated by the heater 9 increases,
Via the insulating tube 8 (at the bent part 7, the gap 14
and the insulating tube 8), and the operating portion 5 of the bimetal 2 falls toward the low expansion portion side (in the direction of the arrow).

With this configuration, the direct heating part is almost completely eliminated, making it an indirect heating type. Moreover, by providing the gap 14 in the bending part 7, the thermal time constant is larger than that of the conventional one, and the power output is 5.5KW or more. Even if applied to 7.5KW
At around 500% I _N, there is a delay in heat transfer and the power overcurrent characteristics become satisfactory. Further, by providing the gap 14, when the bimetal 2 is deflected, the heater 9 does not act as resistance to the deflection. Furthermore, compared to the conventional winding method, the structure and assembly are simplified because it is only applied to one side of the bimetal 2.

In the remote control type circuit breaker, the electric path includes the load side terminal 15, the coil 17 of the short circuit sensor 16, the braided copper wire 11, the heater 2, the bimetal mounting part 3a, the frame 4, the braided copper wire 18, the movable contact 19, It is composed of a fixed contact 20, a copper wire 1, and a power supply terminal 22. Further, 23 is a trip link that faces the gap adjustment screw 6 of the bimetal 2 and also faces the short circuit sensor 16, and 24 is latched to the trip link 23. Latchlink, 25
is a handle, and 26 is a remote control electromagnet. When the handle 25 is tilted to the left about the shaft 27 with the latch link 24 latched to the trip link 23 (FIG. 4), the movable contact 19 moves the latch link connecting shaft 28. Open the pole at the center (off) and turn the handle 2
5 to the right (FIG. 4), the movable contact 29 contacts the fixed contact 30 and turns on. This operation can also be performed by driving the electromagnet 26 with a remote signal to operate the handle 25. in this case,
The handle 25 is held in each state by the holding force of the plunger 32 of the permanent magnet 31 of the electromagnet 26. On the other hand, in the on state, bimetal 2 is deflected due to overcurrent.
When the trip link 23 is rotated and the latch link 24 is unlatched by pushing the trip link 23 with the gear adjustment screw 6 or by pushing the trip link 23 with the short circuit sensor 16 that detects a short circuit accident, the latch link 24 rotates around the shaft 33. Spring 3
4, the shaft 28 moves and the movable contact 39 separates from the fixed contact 30, resulting in a trip state. Resetting is performed by turning the handle 25 to the off side.

Note that 35 is a contact pressure spring, 36 is a manual trip lever, 37 is an arc extinguishing device, 38 is a remote signal input terminal, and 39 is a trip display device.

In addition, in this invention, even if one end of the heater 9 is fixed to the base end 3 of the bimetal 2, the frame 4
It may be fixed directly to. Furthermore, the heater 9 may be provided along the inside of the bimetal 2 instead of the outside.

[Effect of idea]

This invention has the advantage that it can be applied to a relatively high-capacity type, and satisfies power overcurrent characteristics with a simple configuration.

[Brief explanation of the drawing]

Figure 1 is a side view of one embodiment of this invention, Figure 2 is its front view, Figure 3 is a perspective view of the heater, Figure 4 is a sectional view of the remote control type circuit breaker, and Figure 5. 1 is a diagram showing a conventional electrical circuit configuration. 2... Bimetal, 3... Base end, 5... Operating part, 7... Bent part, 8... Insulating tube (insulator), 9... Flexible heater, 9a... One end, 1
0...Holding piece, 13...Bending portion, 14...Gap.

Claims (1)

[Scope of utility model registration request] A bimetal is bent into an L shape and has one end as a base end and the other end as an operating part, and a gap is provided between the bent part of this bimetal and the bimetal is bent along the bimetal through an insulator and one end is connected to the base. An overcurrent detection device comprising: a flexible heater fixed to one end and having a holding piece formed at the other end to slidably engage with the operating portion.