JPS638045Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an overload relay with phase loss protection that improves the accuracy of detecting phase loss.

BACKGROUND ART Conventionally, as one type of protective relay, there has been a thermal type overload relay with open phase protection that can provide open phase protection. Such a thermal type overload relay with phase loss protection uses a bimetal as the thermal element, and when a phase loss occurs, the amount of displacement between the bimetal of the phase that has lost its phase and the bimetal of the other phase can be reduced. Structures that operate based on the difference have generally been adopted.

FIG. 1 shows an example of the configuration of this type of overload relay with open-phase protection. In other words, as shown in Fig. 1, this overload relay with phase loss protection includes three phase bimetals 4R, 4S, and 4T as thermal elements that bend in response to each phase current, and each bimetal 4R. , 4S, 4T and moves in at least one bimetallic curve.
and a second shifter 2 that comes into contact with each of the bimetals 4R, 4S, and 4T and is prevented from moving when at least one bimetal does not bend; A lever 3 that is movably supported, a portion of which is rotatably supported by an end in the direction of movement of the first shifter 1, and is rotated by the movement of the first shifter 1;
Consisting of an actuating piece 18 that comes into contact with the free end 3a of the lever 3 and operates the contact opening/closing mechanism by rotation of the lever 3, an insulating case 5 that houses each of the above elements, and a cover 6 attached to the insulating case 5. has been done.

FIG. 2 shows the operating state when an open phase occurs in the overload relay with open phase protection configured as described above, and the figure shows a simplified case where the S phase is open. In such a phase failure, a force F = (n-1)P acts on the bimetal of the phase S, where P is the operating force required to operate the contact opening/closing mechanism, and n is the lever size ratio. do. For this reason, this bimetal 4S causes displacement and deteriorates the operation at the time of phase loss. Therefore, in order to reduce this, it is necessary to increase the spring constant of the bimetal 4S, but on the other hand, the spring constant Cb of the bimetal 4 is such that the elastic modulus of the bimetal 4 is E, the width is b,
When the thickness is t and the length is L, it is expressed as Cb=E×b×t ³ /4×L ³ , and the displacement of the open-phase bimetal due to the above acting force F is D ₁
is expressed as D ₁ =1/Cb×F =4×L ³ ×F/E×b×t ³ . On the other hand, the amount of displacement D ₀ of the bimetal due to the heat generated by the current during normal times when there is no open phase is expressed as D ₀ = K×L ² ×θ/t ³ where K is the curvature constant and θ is the bimetal temperature. . If the displacement D ₁ of the bimetal with the open phase is large, the accuracy of detecting the open phase will decrease. Therefore, in order to prevent the operation from becoming worse than the ideal state during phase loss,
Possible methods include increasing the width of the bimetal 4 and increasing the thickness t of the bimetal 4 to increase the temperature of the bimetal 4 by that amount. however,
These disadvantages include that the overload relay becomes larger in size and that the temperature rise is large, degrading the surrounding insulation.

The present invention was developed to solve the above-mentioned problems, and its purpose is to suppress the displacement of the bimetal in the open phase without reducing the displacement of the bimetal due to the heat generated by the current. An object of the present invention is to provide a compact overload relay with open-phase protection capable of performing highly accurate open-phase protection by reducing the deterioration of the phase operation from an ideal state.

In order to achieve the above object, the overload relay with open phase protection of the present invention is made by laminating multiple bimetals of the same size that bend in response to each phase current, and fixing one end of the bimetal. a first shifter that contacts the bimetal of each of the thermal elements and moves with the curvature of the bimetal of at least one of the thermal elements; a second shifter whose movement is prevented when the bimetal of the two thermal elements does not bend; and a second shifter rotatably supported at an end in the direction of movement of the second shifter, and a first shifter located midway. a lever that is rotatably supported at the end in the direction of movement of the lever and is rotated by the movement of the first shifter; and a lever that comes into contact with the free end of this lever and operates a contact opening/closing mechanism by the rotation of the lever. The present invention is characterized in that it is configured to include an actuating piece for activating the actuator, and an insulating case for housing each of the above-mentioned elements.

An embodiment of the present invention shown in the drawings will be described below. 3 and 4 show an example of the configuration of a thermal element used in the thermal type overload relay with open-phase protection of the present invention, and show a left side view and a front view thereof. In the figure, 7 and 8 are two (plural) laminated bimetals that have the same curved direction and the same dimensions, 9 is a support plate that supports and fixes one end of the bimetals 7 and 8, and 10 is the bimetal 7. , 8, and 11 is this insulator 1.
A heating element resistor bent in a U-shape across 0, 1
2 is a fastener for fastening the bimetals 7 and 8 and the heating element resistor 11 together; 13 is a power supply side terminal of the heating element resistor 11; and 14 is a load side terminal of the heating element resistor 11. . In other words, this thermal element has a structure in which a plurality of (two) bimetal sheets 7, 8 are laminated and one end of the bimetal is supported and fixed.

In the overload relay with open-phase protection according to this embodiment using the thermal element having such a configuration as the thermal element, the heat generated in the heating element resistor 11 is transferred to the insulator 10.
It is conducted to the bimetals 7 and 8 through the metal, and the bimetals 7 and 8 are thereby bent. The amount of curvature at this time is the same as when only one bimetal is used. In addition, the operation at the time of phase loss is simplified and shown in Fig. 5. At this time, even if the two bimetals 7 and 8 receive a force of F=(n-1)P, this force is The amount of displacement is one-eighth of the amount of displacement in the case shown in FIG. In other words, since this acting force is shared by the two bimetals 7 and 8, the thickness of the bimetal is considered to have doubled, so the displacement D of the open-phase bimetal due to this acting force F is ₂ becomes D ₂ =4×L ³ ×F/E×b×(2t) ³ =1/8×D ₁ . Therefore, the operation at the time of phase loss can be brought closer to the ideal state, the accuracy of phase loss protection can be improved, and the structure can be extremely compact in terms of external shape.

Note that the present invention is not limited to the above embodiments.

In the above embodiment, two bimetals are laminated as the thermal element, but the present invention is not limited to this, and three or more bimetals may be laminated.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

As explained above, according to the present invention, the amount of displacement of the bimetal during an open phase is suppressed without reducing the amount of displacement of the bimetal due to current heat generation, so the operation during an open phase becomes worse than the ideal state. Therefore, it is possible to provide a compact overload relay with open-phase protection that can perform highly accurate open-phase protection while reducing the amount of damage caused by open-phase protection.

[Brief explanation of drawings]

Figure 1 is a diagram showing an overview of a conventional thermal overload relay with open-phase protection, Figure 2 is a diagram showing its operating status, and Figures 3 and 4 are thermal overload relays according to the present invention. FIG. 5 is a left side view and a front view showing the structure of an embodiment of the thermal element of the relay, and FIG. 5 is a diagram showing the operating state of the thermal overload relay with open-phase protection using the thermal element according to the present invention. 1, 2...Shifter, 3...Lever, 4R,
4S, 4T...bimetal, 5...insulation case,
6... Cover, 7, 8... Bimetal, 9... Support plate, 10... Insulator, 11... Heating element resistor,
12... Stopper, 13, 14... Terminal, 7R, 7
S, 7T, 8R, 8S, 8T...Bimetal.

Claims (1)

[Scope of utility model registration request] A three-phase thermal element is formed by laminating a plurality of bimetals of the same size that bend in response to each phase current, and one end of the bimetal is fixed, and at least A first shifter that moves with the curvature of the bimetal of one thermal element, and the movement is prevented when the bimetal of at least one thermal element does not bend when it comes into contact with the bimetal of each of the thermal elements. a second shifter; a second shifter rotatably supported at an end in the moving direction of the second shifter; It is equipped with a lever that is rotated by the movement of the shifter, an actuating piece that comes into contact with the free end of this lever and operates a contact opening/closing mechanism by the rotation of the lever, and an insulating case that houses each of the above elements. An overload relay with open phase protection, which is characterized by: