KR20060117782A - Thermal overload relay - Google Patents

Abstract

A thermal overload relay is provided to enable a user to selectively check an opening operation of a movable contact point of a main circuit without tripping by selectively operating a compulsory trip test and the opening operation of the movable contact point of the main circuit. A test button(41) has a head unit, and a power transfer unit. The head unit is protruded to an upper part of a thermal overload relay and is pushed or pulled by a user. The power transfer unit is installed to be extended downward from the head unit. When a user pushes the head unit, the power transfer unit transfers a pressure of a user downward. A test link(51) is coupled to the test button(41), and is installed to press a movable contact point of a main circuit to be transited to an opening position. The test link(51) is rotated by a down pressure of the test button(41) and transits the movable contact point of the main circuit to the opening position. A spring(43) provides an elastic force upward to the test button so that the test button(41) is recovered to an original position if the down pressure of the user is removed.

Description

 Thermal Overload Relay {THERMAL OVERLOAD RELAY}

1 is a perspective view of a conventional thermal overload relay,

FIG. 2 is a longitudinal cross-sectional view of the thermal overload relay taken along line II-II of FIG. 1;

3 (a) shows a case in which the opening and closing mechanism of FIG. 2 is in a normal energized state,

3 (b) shows a case where the opening and closing mechanism of FIG. 2 is in a tripped state,

Figure 4 (a) is a perspective view of a test button according to an embodiment of the present invention,

Figure 4 (b) is a perspective view of a test link in conjunction with the test button of Figure 4 (a) in accordance with a preferred embodiment of the present invention,

5 is a perspective view of an auxiliary holder according to an embodiment of the present invention,

6 shows an initial state of the overload relay according to an embodiment of the present invention employing the configuration of FIGS.

FIG. 7A illustrates a state in which the test button of FIG. 6 is pressed down.

FIG. 7B illustrates a state in which the test button of FIG. 6 is pulled up.

 <Description of the symbols for the main parts of the drawings>

11: heater 12: lower case

21: opening and closing mechanism 22: upper case

31: auxiliary holder 33: exposed portion

35: insertion groove 36: protrusion

37: tripping protrusion 41: test button

42: head 43: spring

44: body 45: power transmission lever

48: leg 49: power transmission projection

51: test link 52: bearing part

53: rotating shaft hole 55: vertical ring portion

58: opening projection 60: spring support jaw

The present invention relates to a thermal overload relay, and more particularly to a thermal overload relay having a test apparatus that can not only test whether the relay is normally operated but also differentiate the test range according to the test purpose. It is about.

 In general, the thermal overload relay forms an electromagnetic switch together with a magnetic contactor to prevent the motor from being burned out by tripping the circuit after a predetermined time when the current supplied to the motor exceeds the preset current value. It is an electric device.

In addition, the current of the three phases (R, S, T) flows through the motor, but when any one of the three phases is disconnected and no current flows, an overload occurs as the current is concentrated in the remaining phases. As a result, the temperature rises, which causes problems such as damage to the winding insulation.

In order to prevent this, the overload relay as mentioned above is usually connected to the motor in order to prevent burnout during overload or phase loss.

For this overload relay, Figure 1 is a perspective view of a conventional thermal overload relay, Figure 2 is a longitudinal cross-sectional view of the thermal overload relay taken along the line (II-II) of Figure 1, Figure 3 (a) The opening / closing mechanism of 2 is shown in the normal energized state, and FIG. 3 (b) shows a case in which the opening / closing mechanism of FIG. 2 is in the tripped state.

The overload relay may be classified into a heater part 11 that detects an overcurrent or an image phase and a switch mechanism part 21 that opens and closes the converter in conjunction with deformation of the main bimetal 13 in the heater part 11.

The heater case 12 includes a main bimetal 13, a heater 14, a shifter 15, and the like, which constitute the heater unit 11, and a main terminal through which a current of the motor is input to the outside. Three (10) is common (it is common that it is the same as the number of the main bimetals 13).

In the opening / closing case 22 connected to the upper portion of the heater case 12, a release lever 23, an inversion mechanism 26, a reset button 29, an auxiliary holder 31, etc. constituting the opening / closing mechanism part 21 are embedded.

The release lever 23 is connected to the movement of the shifter 15, more particularly the shifter ring 16, and rotates counterclockwise on the drawing, and the temperature compensated bimetal 24 And a protruding nipple 25 that rotates in conjunction with rotation to push down the central portion 27 of the reversal mechanism 26.

The reversal mechanism 26 includes a central portion 27 and a reversal spring 28 fitted between the central portion 27 and the reversal mechanism 26, and in the normal state as shown in FIG. 27 is lifted above the reversal mechanism 26, and this state is maintained by the reversal spring 28.

The reset button 29 serves to return the trip state as shown in FIG. 3 (b) to the normal state as shown in FIG. 3 (a). This trip state will be described in more detail below along with the normal energized state. In addition to the reset button 29, the upper cover 30 is arranged with an adjustment dial 29 'that can adjust the capacitance of the relay.

The auxiliary holder 31 is provided with a projection 36 positioned directly below the main circuit movable contact 95 and a reversal mechanism 26 so as to move the main circuit movable contact 95 to the open position. An insertion groove 35 formed between the upper and lower protrusions is formed at the middle portion in the longitudinal direction (see FIG. 5). The upper end of the auxiliary holder 31 is in a closed state in a state change of the reversal mechanism 26, that is, in an end state in which the end to which the main circuit movable contact 95 is attached as shown in FIG. 3A is turned down. The upper cover 30 is raised to the upper cover 30 by the transfer of the vertical driving force according to the reverse change of the furnace, that is, the reverse change to the state in which the end is flipped upward, or vice versa, as shown in FIG. 3B. (30) It is concealed to the bottom. Through this, the user can visually determine the trip state.

The inversion mechanism 26 is provided with the inversion mechanism movable contact 97 at the front-end | tip, and is provided in the position which the inversion mechanism fixed contact 98 corresponding to the inversion mechanism movable contact 97 opposes, and operates these inversion mechanisms. The contact 97 and the inverting mechanism fixed contact 98 are spaced apart (opened) from each other in normal opening. The main circuit movable contact 95 and the main circuit fixed contact 96 are also paired with each other and are in contact with each other (closed) in a normal energized state. The tip end of the reversing mechanism 26 with the reversing mechanism movable contact 97 is fitted into the insertion groove 35 of the auxiliary holder 31, and the main circuit movable contact 95 is the protrusion 36 of the auxiliary holder 31. Put on). The inverting mechanism fixed contact 98 is mounted below the reset button 29. An auxiliary terminal 10 ′ electrically connecting each of the contacts 95 to 98 and a motor controller (not shown) is installed outside the upper case 22. Since it is connected to the contact 95 to 98, the auxiliary terminal 10 'is composed of a total of four.

Now, the normal energized state and tripped state of the conventional thermal overload relay will be described in detail with reference to FIGS. 3 (a) and 3 (b) as follows.

When an overcurrent flows or an image formation occurs in the electric circuit, it is transmitted through the main terminal 10 (see FIG. 1), and accordingly, a coil-shaped heater 14 wound on the main bimetal 13 in the heater case 12. Will generate heat. When the main bimetal 13 causes a shape displacement by the heat, and the shifter 15 moves to the right in FIG. 3, the shifter ring 16 counterclocks the temperature compensation bimetal 24 of the release lever 23. Rotate in the direction.

By this rotational movement, the tap 25 of the release lever 23 presses the center portion 27 of the reversing mechanism 26 downward on the drawing. Accordingly, when the reversal mechanism 26 and the central portion 27 cross the horizontal critical point, the tip portion of the reversal mechanism 26 is flipped upward and the central portion 27 is reversed as opposed to the normal opening as shown in FIG. Will come down. At this time, as in normal energization, this state is maintained by the reverse spring 28. This state is further referred to as a "trip state", which is illustrated by way of example in FIG.

In this trip state, the auxiliary holder 31 rises upward, and accordingly, the main circuit movable contact 95 rises due to the upward pressure of the lower protrusion 36 of the auxiliary holder 31, thereby causing the main circuit movable contact 95 to rise. And the main circuit fixed contact 96 are separated from each other to make a trip to open the circuit. Accordingly, the current applied to the motor is cut off to prevent burnout of the motor.

When the cause of the overcurrent or the phase of the circuit is eliminated and the user presses the reset button 29, the inverting mechanism fixed contact 98 and the inverting mechanism 26 in which the inverting mechanism movable contact 97 is attached to each other are lowered simultaneously. When the reversal mechanism 26 reverses the aforementioned threshold point, the tip portion of the reversal mechanism 26 is flipped down and is reversed to a "normal open state" in which the central portion 27 rises relatively. In addition, the reset button 29 returns to its original position by the elastic force of the terminal 98 (98).

Whether the transition from the trip state to the normal state or vice versa is stable is one of the important factors regarding the reliability of the relay. More specifically, it is important whether the main circuit movable contact and the main circuit fixed contacts 95 and 96 are properly separated (opened). Therefore, it is necessary to test whether such operation is performed properly before installing and operating the relay.

To this end, a test method of pulling up the exposed portion 33 of the auxiliary holder 31 seated in the groove formed in the relay upper cover 30 using a nail or a small driver is generally used. That is, by using a mechanism in which the exposed portion 33 protrudes out of the relay in the trip state and is exposed, the relay in the normal state is forcibly tripped. The return to the normal state may be performed by using the reset button 29.

However, the above-described conventional test method is not simple in its implementation. That is, as described above, it is a method of pulling up the exposed part 33 seated in the groove of the upper cover 30 by using a nail or a screwdriver, which may not be easy.

Further, although the main concern in this test is whether the main circuit movable contact 95 and the main circuit fixed contact 96 are normally opened, changing the relay to a trip state can be an excessive test. In particular, excessive forced tripping of the relay deforms important components such as the auxiliary holder 31, the main circuit movable contact 95, and the inverting mechanism movable contact 97, or changes the alignment between the components, resulting in a failure of the relay and Problems that cause malfunctions occur.

In order to solve the above problems, an object of the present invention is to provide a thermal overload relay that can selectively test whether the main circuit operating contact of the thermal overload relay is in normal operation. It is another object of the present invention to provide a thermal overload relay having a test apparatus capable of testing not only the main circuit movable contact but also the inverting mechanism movable contact at the same time in the trip position.

One object of the present invention as described above is to be electrically connected to each of the power supply and the load for the opening and closing of the circuit between the power supply and the load, and in the closed position when energizing the normal current on the circuit and to the open position when the overcurrent energizing on the circuit A main circuit fixed contact fixedly installed corresponding to the displacing main circuit movable contact and the main circuit movable contact, and attached to an inverting mechanism and in an open position by the inverting mechanism when energizing the normal current on the circuit, and overcurrent energizing on the circuit. A reversing mechanism movable contact which is displaced to the closed position by the reversing mechanism and a reversing mechanism fixed contact fixedly installed in correspondence with the reversing mechanism movable contact, and connected to one end of the reversing mechanism movable contact and driven by the main circuit movable contact. Can be transferred to the open position, and the inverting mechanism movable contact when the overcurrent is energized in the circuit In the thermal overload relay having an auxiliary holder for driving the main circuit movable contact to the open position according to the displacement to the closed position,

Protruding to the upper portion of the thermal overload relay is provided with a head portion that can be pressed or drawn by the user, and a power transmission unit installed downward extending from the head portion and descends when the user presses the head portion to transmit the pressing force of the user downward A test button of the main circuit movable contact;

It is connected to the test button and driven, and is installed at a position capable of pressurizing the main circuit movable contact to the open position, and is rotated by the downward pressing force of the test button to press the main circuit movable contact to the open position A test link;

And a spring that provides an elastic force upward to the test button so that the test button is returned to its original position when there is no downward pressure applied by the user to the head of the test button. It can be achieved by providing a thermal overload relay according to the invention.

Another object of the present invention is installed in a position that can be in contact with the auxiliary holder, and when the user pulls the test button upwards, the user's upward pull force is transmitted to the auxiliary holder to move the main circuit movable contact to the open position. It can be achieved by providing a thermal overload relay according to the present invention, characterized in that it further comprises an auxiliary holder driving unit for driving and driving the reversing mechanism movable contact to the closed position.

The objects and the construction and operation of the means of achieving the present invention will be more clearly understood from the following detailed description with reference to the accompanying drawings showing a thermal overload relay according to a preferred embodiment of the present invention.

First, as shown in FIG. 6, the thermal overload relay of the present invention is installed to be electrically connected to the power and the load for the opening and closing of the circuit between the power and the load as in the prior art, and the closed position when the normal current is energized on the circuit. And a main circuit fixed contact 96 and a reversing mechanism 26 fixedly installed in correspondence with the main circuit movable contact 95 and the main circuit movable contact 95 which are displaced to the open position when the overcurrent is energized on the circuit. And an inverting mechanism movable contact 97 and an inverting mechanism movable contact which are in the open position by the inverting mechanism 26 when energizing the circuit and shifted to the closed position by the inverting mechanism 26 when the overcurrent is energized on the circuit. 97 is driven in correspondence with the inverting mechanism fixed contact 98 which is fixedly installed in correspondence with 97) and one end of the inverting mechanism movable contact 97, and is capable of power transmission to displace the main circuit movable contact 95 in the open position. And an auxiliary holder 31 for driving the main circuit movable contact 95 to the open position according to the circuit when the inverting mechanism movable contact 97 is displaced to the closed position when the overcurrent is energized.

Referring to the accompanying drawings, the configuration and the operational effects of the present invention of such a thermal overload relay is as follows.

Figure 4 (a) is a perspective view of a test button according to an embodiment as a preferred component of the present invention, Figure 4 (b) is a characteristic component of Figure 4 (a) in accordance with a preferred embodiment of the present invention 5 is a perspective view of a test link linked with a test button, and FIG. 5 is a perspective view showing a characteristic configuration of an auxiliary holder according to an exemplary embodiment of the present invention.

A thermal overload relay having a test apparatus according to an exemplary embodiment of the present invention includes a test button 41 and a test link 51.

First, the test button 41, as shown by way of example in Fig. 4 (a), protrudes largely above the thermal overload relay, the user can press the head portion 42, and extends downward from the head portion It is installed and consists of a power transmission portion consisting of a body portion 44 and the leg portion 48 to lower when the user presses the head portion 42 to transmit the pressing force of the user downward.

The head portion 42 is a portion exposed from the upper part of the thermal overload relay, more specifically, the upper part of the upper cover 30 (see FIG. 1). The user can test the relay by pulling or pressing it. . The outer circumferential surface of the head portion 42 is formed with a concave portion 42 'recessed along the outer circumferential surface so that the user can easily grip and pull the head portion 42.

The test button 41, at the lower end thereof, that is, at the lower end of the leg portion 48, the power transmission protrusion 49 protruding in one horizontal direction to transmit the downward pressing force to the test link, and the upward pulling force. Power transmission lever portions 45 and 46 extend in different horizontal directions for delivery to the auxiliary holder 31. The first power transmission lever part 45 of the power transmission lever parts 45 and 46 is a horizontal extension part which extends from the upper end of the leg part 48 to the installation position of the auxiliary holder 31, and has a second power source. The transmission lever portion 46 is a horizontal direction for transmitting the upward drawing force extending from the extended end of the first power transmission lever portion 45 to the bottom of the tripping protrusion 37 formed in the auxiliary holder 31 again. It is an extension.

 A central hole 43 'is formed at an upper end of the body 44, and a spring 43 is installed at the central hole 43'.

 A stopper 47 is formed at the lower end of the body 44 to protrude in both directions horizontally. The stopper 47 is fixed to a predetermined position of the inner wall of the upper case 22 of the thermal overload relay when the stop button 41 is raised as the head portion 42 is pulled up, so that the spring 43 The rising limit of the test button 41 is determined by abutting the spring support jaw 60 supporting the.

 When the head portion 42 is pulled upward, the upper end of the spring 43 is compressed by limiting the lift by the upper cover 30 (see FIG. 1). On the contrary, when the head 42 is pushed down, the lower end of the restoring spring 43 is compressed due to the lowering of the spring restraint 60 provided in the case cover 33 '. When the user pulls or presses the head portion 42 by the elastic restoring force of the compressed spring 43, and then releases the head portion 42 after testing the trip test of the relay or the normal operation of the main circuit movable contact. The test button 41 automatically returns to the initial position.

As shown in FIG. 4B, the test link 51 has a rotation shaft portion 52 having a rotation shaft hole 53, an upward extension from the rotation shaft portion 52, and a power transmission protrusion 49 fitted therein to rotate the rotational force. Vertical ring portion 55 having an inner circumferential surface formed of a vertical long hole 56 for receiving the transmission, and extends from the rotating shaft portion 52 toward the main circuit movable contact 95 to rotate about the rotating shaft portion 52 It is provided with an opening projection 58 which can displace the main circuit movable contact 95 separately from the main circuit fixed contact 96. Reference numerals 55 'and 55 "denote upper and lower surfaces of the vertical long hole 56, respectively, and indicate the length of the vertical long hole from the lower surface 55" to the upper surface 55' as "L". This vertical long length (L) is the stroke distance that the test button 41 moves vertically, that is, the stopper 47 when the user pulls the head 42 upward to trip the relay according to the present invention. ) Has a predetermined length such that it is longer than a predetermined distance by which it reaches the spring support jaw 60 and stops. Therefore, as shown in FIG. 7B, when the user pulls the head 42 upward for the trip test, the rising limit of the test button, that is, the stopper 47 comes into contact with the spring support jaw 60 and stops. It does not contact the upper surface 55 'of the vertical slot 56 even at the limit.

A rotating shaft portion (not shown) protruding from one of the inner walls of the relay upper case 22 (see FIG. 1) is inserted into the rotating shaft hole 53 of the rotating shaft portion 52 to rotate the test link 51. I support it.

Reference numeral 57 is a horizontal extension provided between the rotation bearing 52 and the opening projection 58.

Now, the configuration and operation of the auxiliary holder 31 in conjunction with the rise of the test button 41 when the user pulls the test button 41 upward to trip the relay will be described with reference to FIG. 5.

As can be seen in Figure 5, the auxiliary holder 31 according to an embodiment of the present invention is the power transmission lever 45, 46, more specifically for the second power transmission of the test button 41 And a tripping protrusion 37 protruding on the upward movement path of the second power transmission lever portion 46 so as to be interlocked with the upward movement of the lever portion 46.

Reference numeral 35 is an insertion groove which is formed by two upper and lower protrusions protruding from the longitudinal middle portion of the auxiliary holder 31 and into which the distal end of the inversion mechanism 26 supporting the inversion mechanism movable contact 97 is inserted. Reference numeral 36 is formed to protrude from the lower end portion in the longitudinal direction of the auxiliary holder 31 to the position directly below the main circuit movable contact 95, so that the main circuit movable contact 95 is fixed to the main circuit as the auxiliary holder 31 is raised. It is a protrusion pushing up from 96.

Now, a test operation of a thermal overload relay according to an exemplary embodiment of the present invention will be described with reference to FIGS. 6 and 7.

 FIG. 6 illustrates an initial state of a thermal overload relay according to an exemplary embodiment of the present invention employing the configuration of FIGS. 4 to 5, and FIG. 7A illustrates a state in which the test button of FIG. 6 is pressed down. (Hereinafter, also referred to as 'main circuit contact open state'), and FIG. 7 (b) shows a state in which the test button of FIG. 6 is pulled up (hereinafter, also referred to as 'forced trip state').

As illustrated in FIG. 6, in the initial state, the second power transmission lever portion 46 of the test button 41 and the tripping protrusion 37 of the auxiliary holder 31 are spaced apart or lightly contacted with each other. It has no physical impact.

The opening projection 58 of the test link 51 and the main circuit movable contact 95 are also spaced apart from each other, so that the main circuit movable contact 95 is closed in a state in which the main circuit fixed contact 96 is in contact with the power supply side. From the current through the relay of the present invention to the load side.

The power transmission protrusion 49 of the test button 41 is in a state of being in close or light contact with the lower surface 55 "of the inner circumferential surface of the vertical ring portion 55 of the test link 51. The spring 43 Is in a relaxed state between the top cover 30 (see Fig. 1) and the spring support 60.

When the user presses the head part 42 of the test button 41 to test whether the main circuit movable contact is normally operated, as shown in FIG. 7 (a), the power transmission lever parts 45 and 46 are illustrated. ) Is lowered in the vertical direction, and the power transmission protrusion 49 of the test button 41 presses the lower surface 55 ″ of the vertical ring portion 55 of the test link 51. 43 is compressed between the descending head portion 42 and the fixed spring support jaw 60. The test link 51 is thus rotated clockwise in the drawing about the rotational axis portion 52. Thus, the opening projection 58 of the test link 51 is also rotated clockwise to separate the main circuit movable contact 95 from the main circuit fixed contact 96 and lift it upwards. The movable contact 97 and the reversing mechanism fixed contact are in an open state separated from each other. Then, the opening operation of only the main circuit contact point at which the main circuit movable contact 95 is opened from the main circuit fixed contact 96 is completed.

When the user releases the test button 41 in this state, the test button 41 is returned to the initial state raised as shown in FIG. 6 by the elastic restoring force of the spring 43. Accordingly, the opening projection 58 of the test link 51 is also spaced downward from the main circuit movable contact 95 while rotating counterclockwise, and the main circuit movable contact 95 is movable with one end fixed and a leaf spring. Since the state is attached to the other end of the child (unsigned), it returns to the initial state, that is, the state in contact with the main circuit fixing contact 96 by the elastic restoring force of the mover.

It should be noted here that only the main circuit movable contact and the main circuit fixed contact 95 and 96 can be selectively tested in the opening operation of the main circuit contact as described above. The mechanical movable contact 97 and the auxiliary holder 31 do not have to physically trip the relay by eliminating physical effects.

 When the user pulls the head portion 42 of the test button 41 upward in the state of returning to the initial state as shown in FIG. 6, the test button 41 as illustrated in FIG. 7B. The power transmission lever portions 45 and 46 are raised to press the tripping protrusion 37 of the auxiliary holder 31 from below to upward to raise the auxiliary holder 31. At this time, the spring 43 is compressed between the body portion 44 and the fixed upper cover 30 of the rising test button 41. As the auxiliary holder 31 ascends, one end of the inverting mechanism 26 inserted into the insertion portion 35 of the auxiliary holder 31 interlocks and the left side in the drawing of the inverting mechanism 26 is raised. Accordingly, the reversing mechanism movable contact 97 attached to one end of the reversing mechanism 26 is in contact with the reversing mechanism fixed contact 98 unless another external force is applied while the reversing mechanism 26 is inverted. At the same time, the auxiliary holder 31 is also held in an elevated state. In addition, at this time, the main circuit movable contact 95 is forced from the main circuit fixed contact 96 by the protrusion 36 of the lower end of the auxiliary holder 31 pushing the main circuit movable contact 95 upward. Stays in the state. This forced trip operation is executed only by pulling the test button 41, which is simpler than the conventional method. When the user releases the test button 41, the test button 41 returns to the initial state by the elastic restoring force of the restoring spring 43 that has been compressed by the upper cover 30. In addition, the trip state of the relay is returned to the initial state of FIG. 6 by applying an external force of pressing the reset button 29 (see FIG. 1).

 As can be seen from above, when the user needs to forcibly trip the relay in order to check whether the relay is normally operated, the user may pull the test button 41. In addition, if it is not necessary to force the trip and only checks whether the main circuit movable contact and the fixed contact 95 and 96 are normally opened, it is only necessary to press the test button 41. The forced trip mode and the contact open mode are thus easily achieved. Further, the forced trip test operation and the main circuit contact opening test operation can be achieved only by changing the operation directions of the same test button 41. In addition, the forced trip test and the main circuit contact opening test can be selectively operated so that the user can selectively check whether the opening operation of the main circuit movable contact is normally performed without forcibly tripping.

Claims (5)

The main circuit movable contact and the main circuit which are electrically connected to the power and the load for the opening and closing of the circuit between the power and the load, respectively, and are in the closed position when the normal current is energized in the circuit and are displaced to the open position when the overcurrent is energized in the circuit. A main circuit fixed contact fixedly installed in correspondence with a furnace movable contact, and attached to a reversing mechanism, and in an open position by the reversing mechanism when energizing the normal current on the circuit, and a closed position by the reversing mechanism when overcurrent energizing the circuit. A reversing mechanism movable contact that is displaced and a reversing mechanism fixed contact fixedly installed corresponding to the reversing mechanism movable contact, and one end of the reversing mechanism movable contact, which is driven and capable of power transmission to displace the main circuit movable contact to an open position. When the inverting mechanism movable contact is displaced to the closed position during overcurrent energization on the circuit, In the thermal overload relay having an auxiliary holder for driving the main circuit movable contact to the open position, Protruding to the upper portion of the thermal overload relay is provided with a head portion that can be pressed or drawn by the user, and a power transmission unit installed downward extending from the head portion and descends when the user presses the head portion to transmit the pressing force of the user downward A test button of the main circuit movable contact; It is connected to the test button and driven, and is installed at a position capable of pressurizing the main circuit movable contact to the open position, and is rotated by the downward pressing force of the test button to press the main circuit movable contact to the open position A test link; And a spring which provides an elastic force upwardly to the test button so that the test button is returned to its original position when there is no downward pressure applied by the user to the head of the test button. Overload relay. The method of claim 1, Installed in a position contactable with the auxiliary holder, and when the user pulls the test button upward, transfers the upward pull force of the user to the auxiliary holder to drive the main circuit movable contact to the open position and at the same time; The thermal overload relay further comprises an auxiliary holder driving unit for driving the mechanism movable contact to the closed position. The method of claim 1, wherein In order to enable the user to easily pull the head in the gripped state, the thermal overload relay is characterized in that the outer peripheral surface of the head portion is formed with a recess recessed along the outer peripheral surface. The method according to claim 1 or 2, The test button includes a power transmission protrusion projecting in a horizontal direction to transmit the downward pressing force to the test link, and a power transmission lever portion extending in a horizontal direction to transmit the upward draw force to the auxiliary holder; The test link includes a vertical ring portion having a rotation bearing portion, an inner circumferential surface extending upwardly from the rotation bearing portion, and formed by a vertical hole for receiving the rotational force through which the power transmission protrusion is inserted, and the rotational rotation from the rotation bearing portion. A protruding portion which extends toward a movable contact and rotates about the rotational bearing part to displace the main circuit movable contact separately from the main circuit fixed contact; The auxiliary holder is a thermal overload relay, characterized in that it is provided with a tripping protrusion protruding on the upward movement path of the power transmission lever portion so as to interlock with the upward movement of the power transmission lever portion of the test button. The method of claim 4, wherein When the vertical hole of the test link is pressed downwards in the head of the test button, the power transmission protrusion of the test button presses the lower surface of the vertical ring part, but the upper limit of the test button is raised even when the head is pulled upward. Thermal overload relay, characterized in that it has a length so as not to contact the upper surface of the inner peripheral surface of the vertical ring.

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