JPH04123740A - Circuit breaker for wiring - Google Patents

Abstract

PURPOSE:To easily convert a mechanical circuit breaker for wiring into an electronic type by installing a unified electronic overcurrent trip device on the mechanical circuit breaker for wiring, and by actuating a voltage/ undervoltage trip device through an overcurrent trip signal. CONSTITUTION:When the current flown in a main circuit conductor 4 as well as a through conductor 17 is in an overcurrent state, an overcurrent trip relay 19 is driven by an electronic circuit by which the overcurrent state is detected through a current transformer 16, in the delay time correspondent to the current, and a trip command is sent to a voltage trip device 10, and a trip coil is excited thereby. The locking mechanism of a switch mechanism part 11 is opened by the device 10, and a moving contact is separated therefrom. Different functions are carried out by mechanical or electronic overcurrent trip devices based on operational characteristics; tripping is carried out by an electronic device when the capacity is not more than a rated circuit breaking capacity, while the switch mechanism 11 is separated and actuated by a mechanical device in the current region exceeding the abovementioned level. A circuit breaker for wiring that is available for both mechanical and electronic types can thus be formed.

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to a molded circuit breaker for the purpose of wiring protection.
More specifically, the present invention relates to a molded case circuit breaker that facilitates the selection of overcurrent tripping methods. 2. Description of the Related Art Mechanical and electronic overcurrent tripping devices are known to be provided in molded circuit breakers. Mechanical overcurrent tripping devices use bimetals and electromagnets to detect current, and when an overcurrent flows, the opening/closing mechanism is activated after a predetermined delay time or instantaneously due to the thermal deformation of these and the suction action of the movable iron piece. This acts to open the blocking section. On the other hand, electronic overcurrent tripping devices constantly monitor the current signal detected by the current transformer using an electronic circuit, and when it is determined that an overcurrent condition has occurred, a trip coil is triggered with a delay time corresponding to the magnitude of the current. This outputs a tripping signal. Compared to mechanical types, electronic types have the advantage of being easier to realize the function of adjusting operating characteristics, and the ability to add various alarm functions and display functions.

[Problem to be solved by the invention]

By the way, a molded case circuit breaker equipped with the above-mentioned mechanical overcurrent tripping device (hereinafter referred to as a mechanical circuit breaker) and a molded case circuit breaker equipped with the above electronic overcurrent tripping device (hereinafter referred to as an electronic type circuit breaker) They are positioned as independent models because they have parts that cannot be standardized, such as the main body case and cover, and each type has its own unique manufacturing process. Therefore, conventionally, the user had to specify one of the methods to the manufacturer at the time of ordering, and the method could not be changed after manufacturing. However, mechanical and electronic types each have their own unique advantages, and you may want to use them selectively depending on the application.
In particular, electronic type circuit breakers can provide various additional functions, so if a user can easily change a mechanical molded case circuit breaker to an electronic type, molded case circuit breakers will become extremely easy to use. The present invention has been made in response to such demands, and an object of the present invention is to provide a molded case circuit breaker that can be easily converted from a mechanical molded case circuit breaker to an electronic type circuit breaker.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a current transformer at the load side terminal portion of a mechanical molded case circuit breaker incorporating a voltage tripping device or an undervoltage tripping device. , a through conductor that passes through this current transformer and is connected to the main circuit conductor of the mechanical circuit breaker; a fault current passing through this through conductor is detected via the current transformer, and the magnitude of this fault current is determined; An electronic overcurrent tripping device is installed in which an electronic circuit that generates an overcurrent tripping signal after a predetermined time corresponding to the overcurrent tripping signal is housed in a molded case to form a unit, and the overcurrent tripping signal causes the voltage to be tripped. It is configured to operate a disconnection device or an undervoltage tripping device.

[For use]

When an overcurrent flows through the main circuit conductor of a mechanical circuit breaker equipped with an electronic overcurrent trip device unit, the electronic overcurrent trip device determines the overcurrent condition and responds to the magnitude of the overcurrent. Outputs an overcurrent trip signal after the specified time has elapsed. Therefore, this signal operates a voltage tripping device or an undervoltage tripping device built into the mechanical molded case circuit breaker, thereby opening the molded case circuit breaker and protecting the electrical circuit. In that case, by removing the mechanical overcurrent tripping device before installing the electronic overcurrent tripping device unit, the mechanical molded case circuit breaker can be used as a normal electronic type molded case circuit breaker. Further, by attaching an electronic overcurrent tripping device unit while leaving the mechanical overcurrent tripping device, a molded circuit breaker that can be used in combination with both types can be constructed.

【Example】

Hereinafter, based on FIGS. 1 and 2, the present invention will be implemented when an electronic overcurrent trip device unit is attached to a mechanical molded case circuit breaker to configure a molded case circuit breaker that uses both types. Let's discuss an example. Here, FIG. 1(A) is a schematic vertical cross-sectional view of the main parts of the molded circuit breaker, FIG. 1(B) is its plan view, and FIG.
The figure is an internal wiring diagram of the molded circuit breaker of FIG. 1. First, in FIG. 1, reference numeral 1 denotes a mechanical circuit breaker, and various components are housed in an outer box consisting of a case 2 and a cover 3 made of molded resin. Reference numeral 4 denotes a load-side main circuit conductor with one end serving as a load-side terminal plate, and the other end connected to a movable contact (not shown) via a flexible conductor. 5 is a bimetal of a mechanical overcurrent tripping device, and 6 is a fixed magnet, which are fixed together to the conductor 4 by a rivet 7. 8 is a movable iron piece placed opposite to the fixed magnet 6, and 9 is its return spring. Reference numeral 10 denotes a voltage tripping device, which is disposed on the opposite side of the bimetal 5 and movable iron piece 8 of the mechanical overcurrent tripping device, with a trip cross spar 11a constituting a part of the opening/closing mechanism section 11 in between. On the other hand, reference numeral 12 denotes an electronic overcurrent tripping device unit, which includes a current transformer δ16 mounted on a printed board 15, a through conductor I7 passing through this, and a current transformer 16 in a molded case consisting of a case body 13 and a cover 14. Printed board 1 equipped with an electronic circuit that monitors the current flowing through the through conductor 17 through the
8. The through conductor 17, which houses the overcurrent trip relay 19 and the like controlled by the output of this electronic circuit and is made into a unit, is tightened from the back side to the case body 13 with screws 20, and one end 17a is attached to the circuit breaker body. 1 load side terminal board 4
The other end 17b serves as a terminal board on the new load side. As shown in FIG. 1(B), the case body 13 is attached to the circuit breaker body 1 by fitting an engaging protrusion 13a having a bulge at the tip into a same-shaped mat 2a formed between the phases of the case 2. The connecting end 17a of the through conductor 17 is fastened to the terminal plate 4a from the back side of the case 2 with a screw 21. Note that the groove 2a is used as a standard equipment for mounting an interphase barrier. The cover 14 is secured with screws 22 from the front side, and screws 23 from the back side of the case 2.
are respectively tightened to the case body 13. As shown in FIG. 1(B) and FIG. 2, one end of the contact terminal of the overcurrent trip relay 19 is connected to one phase of the through conductor 17, and the other end is connected to the electronic overcurrent trip device unit. 12 output terminal 24, and further output terminal 2
The other end of 4 is connected to the other phase of the through conductor 17. Lead wires of the voltage trip device 10 are connected to both ends of the output terminal 24 . In such a configuration, when the current flowing through the conductors 4 and 17 becomes an overcurrent state, the electronic circuit that detects this via the current transformer 16 drives the overcurrent trip relay 19 with a delay time depending on the current. A tripping command is sent to the voltage tripping device IO, and a tripping coil (not shown) is energized. As a result, the voltage tripping device 10 is activated by the plunger 10a (see FIG. 1).
B)) is attracted and drives the trip crossbar 11a to the left in the figure, opening the locking mechanism of the opening/closing mechanism section 11 and separating the movable contact 25 (FIG. 2). Here, the mechanical and electronic overcurrent tripping devices each have their own roles in terms of operating characteristics, and if the rated breaking capacity is below, the electronic overcurrent tripping device will trip.
In a current range exceeding this, the movable iron piece 8 of the mechanical overcurrent tripping device resists the return spring 9 and instantly releases the fixed magnet 6.
The trip crossbar 11a is moved to open and close the opening/closing mechanism 11. In addition, if the electronic overcurrent tripping device becomes inoperable due to some abnormality, the trip crossbar lla is pushed by the curvature of the bimetal 5 heated by the heat generated by the conductor 4 due to Joule heat, and the tripping operation is performed. be exposed. Note that in a molded case circuit breaker incorporating an undervoltage tripping device instead of the voltage tripping device 10, this is handled by inverting the control signal for the overcurrent tripping relay 19. Further, in the above embodiment, an example was shown in which both a mechanical and an electronic overcurrent tripping device are used, but it is of course possible to remove the mechanical overcurrent tripping device and use it as a simple electronic molded circuit breaker. It is.

【Effect of the invention】

According to this invention, a mechanical molded case circuit breaker that is already in use can be converted into an electronic molded case circuit breaker by using the built-in voltage tripping device or undervoltage tripping device, or Various alarm functions and display functions unique to electronic overcurrent tripping devices can be easily added to the device, providing flexibility between mechanical and electronic molded circuit breakers, which have traditionally been positioned as completely different devices. It becomes possible to give gender.

[Brief explanation of the drawing]

FIG. 1(A) is a longitudinal cross-sectional view of a main part of an embodiment of the present invention.
Figure (B) is a plan view thereof, and Figure 2 is an internal wiring diagram of the molded circuit breaker of Figure 1. l...Mechanical hardwired circuit breaker, 4...Main circuit conductor, 1
0... Voltage tripping device, 11... Opening/closing mechanism section, ll
a...Trip crossbar 12...Electronic overcurrent trip device unit, Engineering 6...Current transformer, 17...Through conductor.

Claims (1)

[Claims] 1) A current transformer is installed at the load side terminal portion of a mechanical molded case circuit breaker with a built-in voltage trip device or undervoltage trip device, and the main circuit conductor of the mechanical molded case circuit breaker passes through this current transformer. A through conductor connected to the through conductor, an electronic circuit that detects a fault current passing through the through conductor via the current transformer, and generates an overcurrent trip signal after a predetermined time corresponding to the magnitude of the fault current, etc. is housed in a molded case and equipped with a unitized electronic overcurrent tripping device, and the voltage tripping device or the undervoltage tripping device is operated by the overcurrent tripping signal. Hardwire circuit breaker.