JP4075316B2 - Thermal relay with CT - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal relay with CT applied to a large current circuit in which a CT (current transformer) is combined with a thermal relay, and a secondary output of the CT is operated by energizing a heater element of the thermal relay.
[0002]
[Prior art]
From the same applicant of the present invention, the thermal relay with CT described above has a configuration in which the laminated core of the CT is sandwiched and fixed from the left and right with a two-part insulation case to reduce the number of parts. Japanese Patent Laid-Open No. 2000-156145 has been proposed previously, and its assembly structure is shown in FIGS.
[0003]
In each figure, 1 is a CT, 2 is a thermal relay mounted externally on CT1, and CT1 is a frame-shaped laminated iron core 3 in which a large number of magnetic steel plates 3a are laminated, and a primary conductor 4 penetrating the iron core. The lead wire of the secondary winding 5 comprises an assembly of a secondary winding 5 wound around the winding frame 5a and fitted into the iron core 3, and an insulating case (molded product of thermoplastic resin) 6. 5b is connected to a heater element (not shown) built in the thermal relay 2 so that the thermal relay 2 is operated with a secondary output of CT.
[0004]
Further, as shown in FIG. 5, embosses 3b are formed for each sheet at several locations of the magnetic steel plates 3a constituting the laminated core 3, and the magnetic steel plates 3a are laminated by overlapping the embosses 3b. Yes.
On the other hand, the insulating case 6 has a split structure in which split cases 6a and 6b whose one side is open are overlapped on the left and right and fastened with bolts 7, and the laminated core 3 is sandwiched between the split cases 6a and 6b. A rib piece 6c is formed, and in the assembled state of CT1, the laminated iron core 3 is sandwiched from the left and right via the rib piece 6c and fixed in place as shown.
[0005]
The operation principle of the thermal relay with CT having such a configuration is well known, and the description thereof is omitted here.
[0006]
[Problems to be solved by the invention]
The above-described thermal relay with CT is intended for adaptation to a load circuit with a large rated current, and its operation characteristics often require a longer operation time than the operation characteristics of the thermal relay itself mounted on the CT. .
Therefore, in order to cope with such a demand for slow operation characteristics (referred to as “slow-acting type” with respect to “standard type”), the conventional CT thermal relay has a secondary CT in the rated current range. Designed to give the output a linear characteristic and to have a saturation characteristic for the secondary output in the overcurrent region beyond that, keep the current flowing to the thermal relay low, and increase the operating time of the thermal relay (for example, Even if an overcurrent of 7 times the rated current flows on the primary side of CT, the operation time of the thermal relay will be settled if the secondary output is suppressed to about 5 times the settling current of the thermal relay. When the delay characteristic with a longer operation time is required, the method shown in FIGS. 6 and 7 is used.
[0007]
That is, in FIG. 6, a resistor 8 is externally connected in series as a secondary burden of CT1, and the current flowing through the heater element 2a of the thermal relay 2 is reduced to a low value, thereby making the multiple of the settling current of the thermal relay actual. However, the operation time is lengthened by keeping it low. In FIG. 7, a saturable reactor 9 is externally connected in parallel with the heater element 2a of the thermal relay 2 on the secondary side of CT1, and the secondary output of CT is shunted to the saturable reactor 9 in the overcurrent region. The operation time of the thermal relay 2 is extended.
[0008]
Incidentally, the conventional methods shown in FIGS. 6 and 7 have the following problems. In other words, a slow acting CT thermal relay with a resistor 8 and a saturable reactor 9 externally attached to the CT has a larger and more complicated structure and a larger installation space than that of the standard type. In addition, there is a problem that heat dissipation measures are required for this, and parts such as the standard structure terminal cover cannot be shared with the slow-acting type.
[0009]
The present invention has been made in view of the above points, and an object of the present invention is to provide a thermal relay with CT that solves the above-described problems and enables the specification to be changed to a delayed type having a long operating time with the same external structure as the standard type. It is to provide.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a frame-shaped laminated iron core laminated with magnetic steel sheets, a primary conductor penetrating the laminated innovation, and wound around a winding frame and inserted into the laminated iron core. In the thermal relay with CT, in which a thermal relay is mounted on a CT consisting of an assembly of secondary winding and insulating case, and the secondary output of CT is energized to the thermal relay, in response to the demand for slow operation characteristics In this case, the thickness of the laminated core in the stacking direction is made smaller than the standard thickness, and a nonmagnetic spacer having a thickness corresponding to the thickness reduction is superposed on the laminated core , and then the insulating case is formed. By sandwiching and fixing, the operation time of the thermal relay is lengthened (Claim 1), and as its specific assembly structure, a CT insulating case is a two-part structure in which the divided cases are combined face-to-face, Each split case has a pair A configuration in which the rib pieces for clamping fixing the laminated core of the standard thickness of the right and left in the state.
[0011]
According to the above configuration, in response to the demand for slow operation characteristics for the thermal relay, the number of laminated steel cores of the CT laminated core is reduced and set to be smaller than the standard thickness, so that the CT can be made as in the conventional case. Without externally attaching a resistor, a saturable reactor, etc., the secondary output of CT can be provided with a saturation characteristic, and a desired delayed operation characteristic can be imparted to the thermal relay.
[0012]
Also, in the CT assembly structure, the non-magnetic spacer is superimposed on the iron core so as to fill the thickness reduction of the laminated core described above, so that the laminated core can be formed without changing the structure, dimensions, and fixing method of the insulating case. Can be clamped and fixed in a standard insulation case.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an assembly structure of a delay type CT-equipped thermal relay according to an embodiment of the present invention will be described based on the embodiments shown in FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the member corresponding to FIG. 3, and the description is abbreviate | omitted.
That is, in the illustrated embodiment, the assembly structure of the thermal relay with CT is basically the same as the conventional standard structure shown in FIGS. 3 to 5, but the laminated iron core 3 of CT1 constitutes the laminated iron core. The number of laminated magnetic steel plates is reduced to be smaller than the standard thickness in FIG. Thereby, when an overload current flows on the primary side of CT, the laminated iron core 3 is magnetically saturated, and the increase in the secondary output of CT1 is suppressed low, and as a result, the operation time of the thermal relay becomes long. The thickness of the laminated iron core 3 is set in accordance with the operating characteristics required for the slow-acting thermal relay.
[0014]
Further, when the laminated core 3 is incorporated in the CT insulation case 6, as shown in the drawing, a nonmagnetic spacer 10 is superimposed on the laminated core 3 so as to compensate for the thickness reduction of the iron core. 6a and 6b are interposed, and the laminated core 3 is sandwiched and fixed at a fixed position in the case via the rib piece 6c. As the nonmagnetic spacer 10, as shown in FIG. 2, a necessary number of nonmagnetic plates having the same thickness as the magnetic steel plate are stacked on the side surface of the iron core 3, and the total thickness of the laminated iron core 3 and the nonmagnetic spacer 10 is overlapped. d can be a predetermined dimension. As a result, a slow-acting CT in which the thickness of the laminated iron core 3 is reduced by using the insulating case made for the standard type as a common part without changing the structure, outer dimensions, and fixing method of the iron core. A thermal relay can be assembled.
[0015]
【The invention's effect】
As described above, according to the present invention, the thickness of the laminated core of CT is set smaller than the standard thickness in accordance with the slow operation characteristics required for the thermal relay with CT. Thus, without adding external resistance, saturable reactor, etc. to the secondary side of CT, just reducing the number of magnetic steel plates that make up the iron core, and adding saturation characteristics to the secondary output of CT, it becomes a thermal relay. Desired slow motion characteristics can be imparted.
[0016]
In addition, regarding the assembly structure of the thermal relay with CT, the insulation case has a two-part structure in which the division cases are stacked face to face, and the division case holds a laminated iron core of standard thickness from the left and right in the assembled state of the CT. The structure is such that rib pieces to be fixed are formed, and the laminated iron core is sandwiched and fixed between the divided cases of the insulating case, with a nonmagnetic spacer having a thickness corresponding to the reduced thickness. With this configuration, the slow-acting type that reduces the thickness of the laminated core using the insulating case made for the standard type as a common part without changing the structure, external dimensions, and fixing method of the core. The CT-equipped thermal relay can be assembled.
[Brief description of the drawings]
FIG. 1 is an assembly structure diagram of a thermal relay with a delay type CT according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the main structure of a CT in FIG. Assembly structure diagram [FIG. 4] Side view of the assembly of the laminated core and secondary winding in FIG. 3 [FIG. 5] Partial enlarged sectional view of the laminated core in FIG. [Fig. 6] Resistance on the secondary side of CT Circuit diagram of the conventional method for connecting and providing the slow operation characteristics to the thermal relay. [FIG. 7] Circuit diagram of the conventional method for connecting the loadable reactance to the secondary side of the CT and imparting the slow operation characteristics to the thermal relay. [Explanation of symbols]
1 CT
2 Thermal Relay 3 Laminated Core 4 Primary Conductor 5 Secondary Winding 5a Winding Frame 6 Insulating Case 6a, 6b Split Case 6c Rib Piece 10 Nonmagnetic Spacer

Claims (2)

The CT is composed of a frame-shaped laminated iron core in which magnetic steel plates are laminated, a primary conductor penetrating the laminated iron core, a secondary winding wound around a winding frame and fitted into the laminated iron core, and an insulating case assembly. In a thermal relay with CT, which is equipped with a thermal relay and energizes the secondary output of CT to the thermal relay, the thickness in the stacking direction of the laminated core is higher than the standard thickness in response to the demand for slow operation characteristics The CT thermal relay is characterized in that the non-magnetic spacer having a thickness corresponding to the thickness reduction is superimposed on the laminated iron core, and is sandwiched and fixed in an insulating case . 2. The thermal relay with CT according to claim 1, wherein the insulating case of CT has a split structure in which the split cases are combined face to face, and each split case has a rib that clamps and fixes a laminated iron core of standard thickness from the left and right in the assembled state. A thermal relay with CT, characterized by having a configuration in which a piece is formed.

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