JP5195313B2 - Electric overcurrent relay control method and thermal overcurrent relay - Google Patents

Description

  The present invention relates to a method for adjusting a thermal overcurrent relay used for the purpose of overload protection of a motor and the like, and a thermal overcurrent relay.

  In the thermal overcurrent relay, when the current value of the main circuit connected to the heater section exceeds a certain value, the reversing mechanism inside the device is activated by the bimetal bending due to the heat generated by the heater section. Similarly, a protective device that prevents accidents such as motor burnout by opening and closing the contacts provided in the device, and using means such as releasing the coil excitation of the magnetic contactor using the contact signal output at that time is there. The range of the current value to be set is determined by the characteristics of the built-in bimetal, heater, and reversing mechanism.

  In the thermal overcurrent relay, the minimum value and the maximum value of the usable current are displayed, and this is called a settling current adjustment range. In addition, the minimum scale is the minimum scale, the maximum scale is the maximum scale, the center scale is the center of the minimum and maximum values, and each scale is further divided into several intervals, and the interpolation scale is provided. . Generally, thermal overcurrent relays have the same external shape (model), different heater specifications, and multiple specifications (rated) with different settling current values and widths. The user selects the model and rating of the thermal overcurrent relay according to the specifications of the protection target such as the motor.

  The operating characteristics of the thermal overcurrent relay at the time of overcurrent energization based on the settling current value at each scale are defined by standards such as IEC 60947-4-1 (JIS C8201-4-1). In this clause, 105% of the settling current does not operate for 2 hours, but after this temperature (the current of 105% of the settling current is energized), the temperature becomes constant and the settling current is continued. There is a stipulation that when over 120% of the current is reached, the thermal overcurrent relay must operate within 2 hours.

  However, due to variations in bimetal plate thickness, width, length, curvature constant, volume resistivity, initial position of the tip, wire diameter, length, volume resistivity of the heater, or dimensional accuracy of each component, etc. The operating time and current value of the dynamic overcurrent relay are different for each product of the thermal overcurrent relay, even within the same rating in the same model.

  On the other hand, a thermal overcurrent relay must operate within the range of the standardized operating characteristics and must be manufactured to meet this requirement. It is necessary to adjust the operating characteristics. This adjustment work is called electric adjustment.

  For example, Japanese Unexamined Patent Application Publication No. 2007-213991 discloses a conventional method for adjusting a thermal overcurrent relay. Specifically, the minimum graduation position and the central graduation position are first determined by forced trip, and then the calculated minimum graduation position and the central graduation position are generally utilized by utilizing the fact that the deformation amount of the bimetal is generally proportional to the square of the energization current. A technique for calculating an angle between a center graduation position and a maximum graduation position from each of current values of minimum, center, and maximum using an angle with the graduation position is disclosed. (Patent Document 1)

That is, the deformation amount of the bimetal is approximately given by n · I ² . Here, n is a constant obtained from the bending constant, operating length, plate pressure, bimetal resistance value, and heater resistance value of the bimetal, and I represents the amount of current flowing to the bimetal. As described above, when the operating current at the minimum scale is I ₁ , the operating current at the central scale is I ₂ , and the operating current at the maximum scale is I ₃ , the bimetal at each of the minimum scale position, the central scale position, and the maximum scale position. The deformation amounts are n · (I ₁ ) ² , n · (I ₂ ) ² , and n · (I ₃ ) ² , respectively. Here, the difference n · (I ₂ ) ² −n · (I ₁ ) ² between the amount of bimetal deformation at the center scale and the amount of bimetal deformation at the minimum scale is proportional to the angle between the minimum scale and the center scale, The difference n · (I ₃ ) ² −n · (I ₂ ) ² between the amount of bimetal deformation and the amount of bimetal deformation at the center scale is proportional to the angle between the center scale and the maximum scale. Therefore, when the angle between the minimum scale and the center scale, which is obtained by the forced trip, is θ1, and the angle between the center scale and the maximum scale is θ2,
θ2 / θ1 = {(I ₃ ) ² − (I ₂ ) ² } / {(I ₂ ) ² − (I ₁ ) ² } (Formula 1)
Thus, θ2 can be calculated.
JP 2007-213991 A

  However, according to the technique of the above-mentioned patent document 1, the variation of the angle θ2 between the central scale and the maximum scale is further larger than the variation σ of the individual thermal overcurrent relay products of the angle θ1 between the minimum scale and the central scale. There was a problem of becoming. This will be described in detail below.

Here, the aim value of the minimum scale position is θL and its variation is a, the aim value of the center scale position is θM and its dispersion is b, the minimum scale position is given by θL ± a, and the center scale position is given by θM ± b. Then, the angle θ1 between the minimum scale and the center scale and the variation σ of each thermal overcurrent relay product are given by the following expressions.
θ1 = (θM−θL) ± (a + b) (Expression 2)
σ = a + b (Formula 3)
If electrical adjustment can be made so that the minimum graduation position and the central graduation position are perfectly at the position where the desired operating characteristics can be obtained, θ1 = θM−θL and σ = 0. However, in actuality, as described above, the operating characteristics of the thermal overcurrent relay are different in each thermal overcurrent relay product, and therefore, in both the minimum scale and the center scale, it slightly deviates from the target position. There are not a few σ.

Here, with regard to the maximum graduation position, if an electrical adjustment method that can determine the position according to the operating characteristics of each thermal overcurrent relay product is adopted, the target value of the maximum graduation position is θH and its variation is c. When the maximum scale position is given by θH ± c, the angle θ2 between the center scale and the maximum scale is given by the following equation.
θ2 = (θH−θM) ± (b + c) (Formula 4)
However, in the method of individually adjusting the graduation positions at the three points, the electric adjustment work becomes complicated, and it is necessary to flow a large current particularly during electric adjustment work on the maximum current side. Therefore, the electric adjustment method described in the above-mentioned Patent Document 1, that is, a technique for calculating the third maximum scale position from both of the minimum scale and the center scale. Has been used.

According to this conventional technique, when {(I ₃ ) ² − (I ₂ ) ² } / {(I ₂ ) ² − (I ₁ ) ² } = α is obtained from the above equation 1, θ2 is expressed by the following equation: Given.
θ2 = α · θ1 (Formula 5)
Here, from the formulas 2 and 3, the formula 5 becomes the following formula.
θ2 = α · (θM−θL) ± α · σ (Formula 6)
From Equation 6, it can be seen that the variation of the graduation position, which was ± σ at θ1, is α times as large as ± α · σ at θ2. Note that alpha is given by Equation 1, since the I ₂ is a schematic median of the minimum current I ₁ and the maximum current I ₃ available, alpha is the relationship shown in the following equation.
α> 1 (Expression 7)
For example, in the case of a thermal overcurrent relay having a minimum usable current value of 2.8 A and a maximum value of 4.4 A, the median value is 3.6 A. Here, α = 1.25> 1 from Equation 1. Table 1 shows an example of the value of α with respect to the rating of the thermal overcurrent relay.

Generally, at the position where the amount of deformation of the bimetal is small, the influence of the ambient temperature and the influence of the deformation being pushed back by the operating pressure from the reversing mechanism are large. Compared to the maximum scale position side that operates at a position where the amount of deformation of the bimetal is large, there is a tendency that the variation from the target position becomes larger, and the following equation is established.
a>b> c (Formula 8)
Therefore,
α · σ = α · a + α · b> b + c (Equation 9)
Thus, when the technique described in the above-mentioned Patent Document 1 is used, the variation becomes larger than when electric adjustment is performed at three points of the minimum scale position, the center scale position, and the maximum scale position.

  Therefore, in the case where electric adjustment is performed only at two points of the minimum scale position and the central scale position, the central scale position is compared with the case where electric adjustment is performed at the minimum scale position, the central scale position, and the maximum scale position. And the maximum graduation position has a large angle variation, and even if the minimum graduation position and the central graduation position are accurately determined by forced trip, it is difficult to obtain the maximum graduation position with high accuracy relative to the target position on the maximum graduation side. There was a problem.

  Further, since the variation included in the angle θ2 between the central scale and the maximum scale is large, θ2 becomes larger than the original target value, and as a result, the adjustment range angle (= θ1 + θ2) of the settling current is increased by the knob in the adjustment mechanism section. There is a problem that the movable range may be exceeded, and the minimum scale or the maximum scale, or both of them, may not be able to be adjusted to the scale position, that is, may not be adjusted.

  As described above, since the deformation amount of the bimetal is proportional to the square of the energization current, normally, the central graduation position and the maximum graduation position where the energization current to the bimetal is larger than the angle θ1 between the minimum graduation position and the central graduation position. The angle θ2 in the middle is wider. Furthermore, in the electric tuning method described in Patent Document 1 described above, the angle θ2 between the center graduation position and the maximum graduation position includes the large variation α · σ as described above, and therefore θ2 is set excessively. was there. In the conventional thermal overcurrent relay, the angle from the central scale position to the movable limit on the minimum scale side is equal to the angle of the movable limit on the maximum scale side. From the above, when setting each scale position with the center scale position as a reference, when setting the minimum scale position, the margin to the minimum scale direction movable limit of the knob is large, whereas the maximum scale position Is set, the angle variation between the center graduation position and the maximum graduation position is large, and as a result, the margin to the maximum graduation direction movable limit of the knob is small. As a result, before the knob is fully turned to the maximum scale position, the knob reaches the movable limit by contacting the case in the adjustment mechanism, and the thermal overcurrent relay is likely to fall out of adjustment. there were.

  Before turning the knob all the way to the maximum graduation position, ensure a wide adjustment range from the central graduation position to the maximum graduation direction adjustment limit in order to avoid the problem that the knob in the adjustment mechanism will become the movement limit. If comprised in this way, conversely, the adjustable range from the center scale position to the movable limit on the minimum scale direction adjustment side will be narrow. Therefore, when setting the minimum scale on the basis of the central scale, before the knob is fully turned to the minimum scale position, the knob in the adjustment mechanism part comes into contact with the case and becomes a movable limit. There was a problem that the relay could easily fall out of adjustment.

  Furthermore, when turning the knob of the adjustment mechanism section, the knob also moves in a direction perpendicular to the surface facing the case while rotating. In addition, this knob comes into contact with the groove in the parts feeder so that the knob can move smoothly in the parts feeder without rotating when passing the knob through the parts feeder in the production process of the thermal overcurrent relay. Two sides are provided. However, since the height of these surfaces is high and the above-mentioned knob moves in the vertical direction, if the adjustment current angle of the settling current (= θ1 + θ2) is large, the knob can be rotated to the minimum scale position or the maximum scale position. Previously, when the surface provided on the above-mentioned knob comes into contact with the case or the like, there is a problem that the adjustment mechanism part becomes a movable limit and falls into an unadjustable state.

  The present invention has been made in view of the above-described problem, and even when electrical adjustment is performed only at two points of the minimum scale position and the center scale position, not only the minimum scale position and the center scale position but also the maximum scale position. Thermal control of thermal overcurrent relays that ensure adjustment accuracy with little variation at each position, and thermal operation that is difficult to fall into an unadjustable state in the settling current adjustment range from the minimum graduation position to the maximum graduation position An object is to provide an overcurrent relay.

The method of controlling the thermal overcurrent relay according to the present invention includes a bimetal that bends in response to a main circuit current, an interlocking plate that transmits the displacement of the bimetal, and a contact that contacts the interlocking plate to perform a trip operation. The reversing mechanism that reverses the open / close state of the switch, the adjustment mechanism that can move the reversing mechanism and adjust the position where the open / close state of the contact is reversed, and the minimum settling current displayed on the thermal overcurrent relay body Operates within the range of operating characteristics defined by the standard in a thermal overcurrent relay with a minimum scale, a central scale, and a scale display with a maximum scale, each indicating the value, median, and maximum As described above, in the electrical adjustment method of the thermal overcurrent relay that adjusts the individual operating characteristics of the thermal overcurrent relay, a predetermined number of thermal overcurrent relays that have completed electrical adjustment work at the minimum scale position and the central scale position. Using current relay, Adjusting the angle of the adjustment mechanism while supplying a current in the range of 105% to 120% of the maximum value of the settling current, and the central scale position of the adjustment mechanism where the thermal overcurrent relay trips the angle of up to scale positions experimentally determined as a sample angles, the mean value of the sample angle from the center of the scale positions of a predetermined number of thermally activated overcurrent relay to full scale position, the center of the scale positions on the same rating from A first step that is set in advance as an angle to the maximum graduation position, a second step that determines the minimum graduation position and the central graduation position by operating characteristics of the thermal overcurrent relay, and the second step. The maximum graduation position is determined by giving an angle from the determined central graduation position to the maximum graduation position at the same rating preset in the first step. And having a third step that.

A bimetal that bends in response to the main circuit current; an interlocking plate that transmits the displacement of the bimetal; an inversion mechanism that reverses the open / closed state of the contact by tripping by contact with the interlocking plate; To adjust the position where the open / closed state of the contact is reversed, the adjustment mechanism part with the movable limit on each of the minimum scale direction adjustment side and the maximum scale direction adjustment side, and the minimum settling current displayed on the product body In a thermal overcurrent relay having a scale, a center scale, and a scale display with a maximum scale, each indicating a value, a median value, and a maximum value, a surface facing the knob case of the adjustment mechanism section; comprises a projection respectively on opposite surfaces to the knob of thermally activated overcurrent relay main body of the case, the movable limit of the adjusting mechanism by both projections abut with each other, the minimum counted from the position of the central scale Than the pivot amount of up adjusting mechanism movable limit of the direction adjusting side, defined as toward the rotation amount from the center of the scale positions to the adjusting mechanism movable limit of the full scale direction adjustment side is wide, and the full scale The direction-side movable limit is the angle from the center scale position to the maximum scale position that is determined in advance for each model rating using a predetermined number of thermal overcurrent relays that have been electrically controlled at the minimum and center scale positions. Further, it is characterized in that it is set in consideration of an error .

  In addition, the knob is formed with two parallel planes, which are provided in order to mount the knob without any delay in the production process of the thermal overcurrent relay, and the length of the faces is the radius of the knob. When the knob is rotated between the minimum scale side movable limit and the maximum scale side movable limit, the tip positions of the two surfaces provided on the knob are the movable lengths of the adjusting mechanism section. It is characterized in that it is spaced apart from a protrusion provided on the case for defining the limit by a predetermined gap.

  As described above, according to the electrical adjustment method of the thermal overcurrent relay described in the present invention, if the minimum scale position and the central scale position are accurately determined by electrical adjustment performed in advance, the minimum scale position and the central scale position In addition, even at the maximum graduation position at a certain angular distance determined for each model rating as described above with reference to the central graduation position, the adjustment variation is suppressed while maintaining the same operation accuracy as the conventional technology. be able to.

  Further, according to the thermal overcurrent relay described in the present invention, in the settling current adjustment range from the minimum graduation to the maximum graduation, it is difficult to be in an unadjustable state, and particularly the maximum graduation position can be reliably adjusted. A thermal overcurrent relay can be provided.

  Furthermore, while the tip positions of the two surfaces provided on the surface facing the knob case rotate the knob from the minimum graduation side movable limit to the maximum graduation side movable limit, a predetermined value is provided on the case protrusion that defines the movable limit of the knob. Since it is configured to be separated from the gap, it is possible to provide a thermal overcurrent relay that is unlikely to be adjusted.

Embodiment 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a thermal overcurrent relay electric conditioning method and a thermal overcurrent relay according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1A to FIG. 1E are configuration diagrams of this thermal overcurrent relay, and FIG. 1A shows the interior when the cover of the thermal overcurrent relay is removed and viewed from the front. FIG. 1 (b) is a structural view, FIG. 1 (b) is an arrow view along the section AA in FIG. 1 (a), FIG. 1 (c) is a left side view of the thermal overcurrent relay, and FIG. FIG. 1E is a top view of the thermal overcurrent relay. FIG. 2 is an enlarged view of FIG.

  1 (a) and 2, a thermal overcurrent relay includes a case 1 in which each component is housed, a cover 2 that covers the case 1, a bimetal 3 that is curved in response to a main circuit current, A heater 4 that is wound around the bimetal 3 and generates heat when a current is supplied to the main circuit, an interlocking plate 5 that transmits the displacement of the bimetal 3, and a reversal that reverses the open / closed state of the contact by the force applied from the interlocking plate 5 And a mechanism unit 20. Here, the reversing mechanism 20 is constituted by the temperature compensating bimetal 6, the reversing plate 7, the tension spring 8, and the reversing support member 9 that supports them. Then, the interlocking plate 5 contacts the tip of the bimetal 3 and transmits the bending displacement of the bimetal 3 to the temperature compensation bimetal 6 of the reversing mechanism unit 20.

  The thermal overcurrent relay further includes a normally closed movable contact 7a provided on the reversing plate 7 and a normally closed fixed contact 10 provided with a normally closed fixed contact 10a. An adjustment screw 11 for rotating the reversing mechanism support member 9 in a direction, a knob 12 that is put on the adjusting screw 11 in a state where a current value and a scale within an adjustable range are printed, and a reversing mechanism portion 20 A rotating lever 13 that rotates according to the operation, a normally-open movable contact 14 that is curved and deformed by being lifted by the rotating lever 13, a normally-open movable contact 14a provided on the normally-open movable contact 14, and a normally-open fixed The normally open fixed contact 15 provided with the contact 15a, the reset bar 16 for returning the reversing mechanism unit 20 from the trip state to the steady state, and the reset method are switched to manual reset or automatic reset. And the switching plate 17, a leaf spring 18 applying a pressing force to the reversing mechanism support member 9 has a reset spring 19 which gives a biasing force to the reset bar 16. Here, the adjustment screw 11, the knob 12, the reversing mechanism support member 9, and the leaf spring 18 constitute an adjusting mechanism portion 21 that adjusts the position where the contact open / close state is reversed.

  First, the basic operation of the thermal overcurrent relay will be described. If some abnormality occurs in a load such as a motor and the current value energized in the main circuit increases, the amount of heat generated by the heater 4 also increases. As a result, the bimetal 3 is bent and its tip position is displaced. Due to this displacement, the interlocking plate 5 moves to the left in FIG. When the amount of movement reaches a certain amount, the lower end 6b of the temperature compensation bimetal 6 comes into contact. When the interlocking plate 5 further moves to the left in FIG. 2, the temperature compensating bimetal 6 is pressed against the lower end portion 6 b by the interlocking plate 5, and the fulcrum portion of the temperature compensating bimetal 6 provided on the reversing mechanism support member 9. It rotates clockwise in FIG. 2 using 9a as a fulcrum.

  The hook 6 a of the pull spring 8 provided on the temperature compensating bimetal 6 is supported by the hook 7 b of the pull spring 8 provided on the reverse plate 7 and the fulcrum of the reverse plate 7 provided on the reverse mechanism support member 9. Since the direction of the force generated in the reversing plate 7 by the tension spring 8 is reversed from the counterclockwise direction in FIG. 2 to the clockwise direction when positioned on the right side in FIG. 2 with respect to the straight line connecting the portion 9b, the reversing plate 7 The rotation starts in the clockwise direction in FIG. 2 with the fulcrum 9b as an axis. When the reversing plate 7 is rotated in the clockwise direction in FIG. 2, the normally closed movable contact 7 a provided on the reversing plate 7 and the normally closed fixed contact 10 a provided on the normally closed fixed contact 10 are opened. That is, the reversing mechanism unit 20 including the temperature compensating bimetal 6, the reversing plate 7, the tension spring 8, and the reversing mechanism support member 9 operates as a toggle mechanism.

  Further, when the reversing plate 7 presses the rotation lever 13, the rotation lever 13 rotates about the protruding shaft 1a provided in the case 1 in the counterclockwise direction of FIG. 2, and the normally open movable contact 14 rotates. The normally open movable contact 14a provided on the normally open movable contact 14 and the normally open fixed contact 15a provided on the normally open fixed contact 15 are closed by being lifted by the protruding piece 13a of the lever 13. This series of operations is referred to as a trip, and a state in which the contact open / close state is reversed by the trip operation (that is, a state in which the normally closed contact is open and the normally open contact is closed) is referred to as a trip state. In the trip state, the normally open movable contact 14 and the normally open fixed contact 15 are bent and deformed by being lifted upward by the rotation lever 13 in FIG. 2, and the rotation of the rotation lever 13 is stopped. stable.

  The reset bar 16 is assembled to the case 1 with an urging force applied upward in FIG. Here, because the load of the motor or the like has recovered from the abnormal state from the trip state, the contact open / close state is reset to the steady state (that is, the normally closed contact is closed and the normally open contact is opened). 2 rotates the rotating lever 13 clockwise in FIG. 2 by pressing the reset bar 16 downward in FIG. 2 against the urging force of the reset spring 16 described above. As a result, the reversing plate 7 is pressed by the rotating lever 13 and rotates counterclockwise in FIG. 2 falls on the left side in FIG. 2 with respect to a straight line connecting the portion 9b and the fulcrum portion 9a of the temperature compensation bimetal 6. As a result, the direction of the force generated in the reversing plate 7 by the tension spring 8 is reversed again from the clockwise direction in FIG. 2 and can be reset.

  Here, in the thermal overcurrent relay, there are two types of methods for performing the above-described reset, manual reset and automatic reset. That is, from the manual reset setting in which the reset bar 16 is pressed and reset by the user by rotating the switching plate 17 about the shaft 17a provided on the switching plate 17 in the counterclockwise direction of FIG. The reset method can be changed to an automatic reset setting that resets the reset bar 16 without requiring the user to press the reset bar 16.

  When the automatic reset is set by the switching plate 17, the normally open fixed contact 15 is pushed down by the protruding piece 17b of the switching plate 17, and the contact gap between the normally open fixed contact 15a and the normally open movable contact 14a is reduced and rotated at the same time. The amount of rotation of the lever 13 in the counterclockwise direction is suppressed. For this reason, the position of the hooking portion 7b of the pulling spring 8 provided on the reversing plate 7 in the trip state is such that the fulcrum portion 9b of the reversing plate 7 provided on the reversing mechanism support member 9 serving as the reset line and the temperature compensation bimetal. 6 so as not to fall to the right side of FIG. 2 rather than the straight line connecting the six fulcrum portions 9a. As a result, the abnormality of the load is recovered, the heat generation of the heater 4 is suppressed, the bimetal 3 is not bent, and the interlocking plate 5 moves to the right in FIG. Is no longer applied, the reversing mechanism 20 automatically returns to the steady state.

  When the knob 12 is rotated clockwise in FIG. 1 (e), the adjusting screw 11 presses the reversing mechanism support member 9 in the downward direction of FIG. It rotates in the clockwise direction of FIG. 2 with the engaging portion between the L-shaped bent portion 9z and the protrusion 1z provided on the case 1 as a fulcrum. Conversely, when the knob 12 is turned counterclockwise in FIG. 1E, the adjusting screw 11 returns to the upper direction in FIG. 2 while spirally rotating, and the reversing mechanism support member 9 is reversed by the pressing force from the leaf spring 18. 2 is rotated counterclockwise in FIG. 2 with an engaging portion between the L-shaped bent portion 9z of the mechanism support member 9 and the protrusion 1z provided on the case 1 as a fulcrum.

  As the reversing mechanism support member 9 rotates in this way, the positions of the fulcrum portion 9b of the reversing plate 7 and the fulcrum portion 9a of the temperature compensating bimetal 6 provided on the reversing mechanism supporting member 9 move, and the interlocking plate 5 And the distance until the lower end 6b of the temperature compensation bimetal 6 abuts also changes, so that the amount of movement of the interlocking plate 5 required before the trip operation can be changed.

  Here, the interlocking plate 5 moves according to the displacement of the bimetal 3, and the bimetal 3 bends according to the amount of heat generated by the heater 4 due to the main circuit current. Therefore, by turning the knob 12, the thermal overcurrent relay is The current value required for the trip operation can be adjusted. The knob 12 displays a usable current range from a minimum value to a maximum value (referred to as a settling current adjustment range) and a scale thereof, with a representative current value called a heater as a median value. .

  By the way, the operating characteristics of the thermal overcurrent relay are the thermal overcurrent relay products that depend on the plate pressure, width, length, bending constant, volume resistivity of the bimetal 3, or variations in the dimensional accuracy of each component. Variations occur individually. For this reason, it is difficult to satisfy the characteristics defined in the standards such as IEC 60947-4-1 (JIS C8201-4-1) without adjusting the thermal overcurrent relay. A so-called electric tuning process is required to adjust the operating characteristics of each product. As one specific operation of this electrical adjustment, when the minimum operating current of the thermal overcurrent relay at each of the minimum, center, and maximum scales is defined as UTC (Ultimate Trip Current), this UTC is the settling current 105. It must be adjusted to be in the range of% to 120%. For example, in the case of a thermal overcurrent relay with a heater nominal of 3.6 A (the settling current adjustment range is 2.8 A to 4.4 A), the minimum scale UTC is in the range of 2.94 A to 3.36 A, and the center scale UTC should be in the range of 3.78A to 4.32A, and maximum scale UTC should be in the range of 4.62A to 5.28A.

  Hereinafter, with reference to FIGS. 3, 4, and 5, an electric tuning method for the thermal overcurrent relay and the thermal overcurrent relay in the present embodiment will be described.

  In the electric tuning method of the thermal overcurrent relay in the present embodiment, the minimum scale position and the central scale position are determined in advance according to the operating characteristics of each thermal overcurrent relay product. For this purpose, for example, there are a method disclosed in Japanese Patent No. 4085728 and a method disclosed in Japanese Patent Application Laid-Open No. 2007-213991. Any method may be used as a method for determining the minimum graduation position and the central graduation position in accordance with the operation characteristics of each thermal overcurrent relay.

  Next, the maximum scale position is determined at a position separated by a predetermined angle calculated in advance for each model rating with reference to the center scale position determined by electrical adjustment. In addition, as a method for calculating the constant angle formed by the center graduation position and the maximum graduation position, there is a method of experimentally obtaining in advance at the design stage of the thermal overcurrent relay. For example, prepare multiple samples of thermal overcurrent relay products of a certain model rating that have been calibrated to determine the minimum scale position and the center scale position, and for each of these samples, little by little from the center scale position. The UTC at the position where the angle is shifted is measured, and the scale position where the UTC is 112.5% of the maximum scale value (the intermediate value between 105% and 120%) is obtained. The graduation position thus determined is the provisional maximum graduation position, and the average value of the central graduation position and the provisional maximum graduation position in a plurality of samples is calculated between the central graduation position and the maximum graduation position in the model rating. A method for determining the angle is conceivable. The method of obtaining the maximum scale position according to the present invention is different from the method of obtaining the maximum scale position by performing the electric adjustment work for each of the thermal overcurrent relay products as described in Patent Document 1, in advance of the model. By determining the center scale position and maximum scale position for each rating, the maximum scale position of the thermal overcurrent relay is determined regardless of the individual characteristics of the thermal overcurrent relay product. And Note that the value of UTC that determines the maximum scale position is not limited to 112.5% of the above-mentioned maximum scale value, but if the target value of UTC is defined within any range from 105% to 120%. Good. However, it is necessary to determine the maximum scale position with the same current as the target value determined above for all the plurality of samples.

  In addition, as a method of calculating the constant angle formed by the center graduation position and the maximum graduation position, the adjustment mechanism is greatly moved from the central graduation position to the maximum graduation direction (at least to 120% of the maximum graduation value so as not to trip) In this state, a predetermined current within a range of 105% to 120% of the maximum scale value is applied for a period of time until the amount of deformation of the bimetal is saturated. Thereafter, the maximum scale position of the sample may be determined by moving the adjustment mechanism portion again from the position after the movement to the center scale position side and manually forcibly tripping.

When the maximum scale is determined at a position apart from the central scale position by a certain angle, a variation c ′ is included with respect to the target position θH of the maximum scale position. The variation c ′ can be obtained in advance by an experimental method for calculating a certain angle formed by the above-described center graduation position and the maximum graduation position. That is, the variation from the temporary maximum graduation position obtained for each sample to the maximum graduation position determined by the set constant angle is c ′. On the other hand, the center graduation position is determined according to the characteristics of each thermal overcurrent relay product using various methods as described above, and is given by θM ± b. From the above, the angle θ2 between the central scale position and the maximum scale position in the present embodiment is
θ2 = (θH−θM) ± (b + c ′) (Equation 10)
Given in. That is, ± (b + c ′) is a variation included in the angle θ2 between the central scale position and the maximum scale position. On the other hand, the angle θ2 between the center graduation position and the maximum graduation position determined by the prior art method is θ2 = α · (θM−θL) ± α · σ as shown in the problem to be solved by the invention described above. (Formula 6)
It is represented by That is, ± α · σ is a variation included in the angle between the central scale position and the maximum scale position determined in the prior art. Above and above,
α> 1 (Expression 7)
Α · σ = α · a + α · b> (b + c ′) (Equation 11)
Therefore, it can be said that the variation included in the angle θ2 between the center graduation position and the maximum graduation position is small as compared with the conventional method. Hereinafter, the fact that Expression 11 holds will be described.

Generally, at the position where the amount of deformation of the bimetal is small, the influence of the ambient temperature and the influence of the deformation being pushed back by the operating pressure from the reversing mechanism are large. Compared with the maximum scale position side that operates at a position where the amount of deformation of the bimetal is large, the variation from the target position tends to be larger. Therefore, the variation from the target position is larger on the minimum scale position side where the operation is performed at a position where the deformation amount of the bimetal 3 is small than on the maximum scale position side where the operation is performed at a position where the deformation amount of the bimetal 3 is large. There is a tendency. That is,
a>b> c ′ (Formula 12)
And the following equation holds.
α · a + α · b> (b + c ′) (Formula 13)
Therefore, it can be said that the above formula 11 holds, and that the variation included in the angle θ2 between the central scale position and the maximum scale position is small as compared with the conventional method.

  Therefore, if the minimum graduation position and the central graduation position are accurately determined by electrical adjustment performed in advance, the central graduation position is used as a reference in addition to the minimum graduation position and central graduation position while maintaining the same operation accuracy as the conventional technology. As described above, it is possible to reduce variation in adjustment of the maximum graduation position at a position separated by a certain angle determined for each model rating at the design stage as described above.

  Here, based on the two predetermined graduation positions, as a means for simply calculating the third graduation position, electric adjustment is performed at two points of the central graduation position and the maximum graduation position, A method is also conceivable in which the minimum graduation position is determined at a position away from the graduation position by a certain angle. However, since there is a relationship of Formula 9 and Formula 12, the minimum scale position and the center scale position where the variation from the target position becomes large as in this embodiment depends on the characteristics of the thermal overcurrent relay product. By determining the position by electrical adjustment that performs positioning, the operation accuracy as a thermal overcurrent relay is ensured, while the maximum graduation position with small variations is determined at a constant angle from the central graduation position. In other words, each scale position can be determined with higher accuracy.

  In addition, the adjustment mechanism of the thermal overcurrent relay described above is provided for the purpose of preventing the knob 12 from spinning freely and for stopping the turning of the reversing mechanism support member 9 before reaching the turning limit. A movable limit is provided on each of the minimum scale direction adjustment side and the maximum scale direction adjustment side.

  Here, the rotation limit will be described in detail below. The reversing mechanism support member 9 rotates clockwise and counterclockwise with the engaging portion of the L-shaped bent portion 9z and the protrusion 1z provided on the case 1 as a fulcrum. The tip of the protrusion 1z has an acute V-shape, and the rotation limit of the reversing mechanism support member 9 is determined by the difference in angle between the 1z V-tip and the 9z L-bend.

  If the knob 12 is continuously rotated (turned idle) in the direction in which the adjustment screw 11 is pushed in a state where the reversing mechanism support member 9 is at the rotation limit, force is applied to the contact portion between the adjustment screw 11 and the reversing mechanism support member 9. If it continues to be added, the corresponding contact may be deformed, and the thermal overcurrent relay may not be used continuously. Conversely, if the knob 12 is turned too far in the direction in which the adjustment screw 11 protrudes, the adjustment screw 11 may come off. In order to prevent falling into these states, in the present embodiment, a protrusion 12a is provided on the surface of the knob 12 at the center scale position and facing the case 1, and the protrusion 1b is formed on the surface of the case 1 facing the knob 12. The movable limit of the adjustment mechanism is determined by the contact of these two protrusions.

  Hereinafter, the positional relationship between the protrusion 12a provided on the knob 12 and the protrusion 1b provided on the case 1 will be described in detail. 3 (a) to 3 (f) are structural views of the knob 12, FIG. 3 (a) is a front view when the knob 12 is viewed from the front of FIG. 1 (e), and FIG. 3 (c) is a rear view of the knob 12, FIG. 3 (d) is a left side view of the knob 12, and FIG. 3 (e) is an oblique left direction of the knob 12 in FIG. 3 (a). FIG. 3F is a perspective view when the knob 12 is viewed from the diagonally left direction of FIG. 3D. 4 (a) and 4 (b) are enlarged structural views of the case 1 to which the knob 12 is attached. FIG. 4 (a) is a view when viewed from the front of FIG. 1 (e). FIG. 4B is a perspective view of the case 1 as viewed from the oblique right direction of FIG. 4A. 5 (a) is an enlarged view of the knob portion of FIG. 1 (a), and FIG. 5 (b) is a diagram showing the positional relationship between the knob protrusion and the case protrusion at the central scale position.

  In FIG. 5B, when the knob 12 is turned clockwise from the center scale position (that is, the state shown in FIG. 5), the protrusion 12a provided on the knob 12 shown in FIG. Rotate clockwise in conjunction. When the amount of rotation becomes θ2 ′ shown in FIG. 5, the side surface 12ar of the projection 12a shown in FIG. 3 (f) and the side surface 1br of the projection 1b shown in FIG. It becomes impossible for the knob 12 to rotate to a position exceeding θ2 ′. That is, the position becomes the maximum scale direction side movable limit of the adjustment mechanism.

  Further, in FIG. 5B, when the knob 12 is turned counterclockwise in FIG. 5 from the center graduation position (that is, the state shown in FIG. 5B), the knob 12 shown in FIG. 3F is provided. The protrusion 12a also rotates counterclockwise in conjunction with the knob 12. When the rotation amount becomes θ1 ′ shown in FIG. 5, the side surface 12al of the projection 12a shown in FIG. 3 (f) and the side surface 1bl of the projection 1b shown in FIG. It becomes impossible for the knob 12 to rotate to a position exceeding θ1 ′. That is, the position becomes the minimum scale direction side movable limit of the adjustment mechanism.

  Here, in the present embodiment, the protrusion 12a provided on the knob 12 and the case 1 are provided so that the maximum graduation direction side movable limit θ2 ′ is larger than the minimum graduation direction side movable limit θ1 ′. The projected protrusion 1b is disposed. That is, the angle from the center graduation position to the movable limit in the maximum graduation direction is widened as θ2 ′> θ1 ′. As a result, since the energization current is large, the amount of deformation of the bimetal 3 is large, the angle θ2 between the center graduation position and the maximum graduation position is large, and when setting the maximum graduation position, the knob is fully turned to the maximum graduation position. This prevents the adjustment mechanism from becoming in an unadjustable state on the maximum direction scale side where the adjustment mechanism part becomes the movable limit before, so-called unadjustable tendency to occur.

  In the present embodiment, the angle θ2 between the center graduation position and the maximum graduation position is a constant angle determined in advance for each model rating with reference to the center graduation position determined by electrical adjustment. By arranging the protrusion 12a provided on the knob 12 and the protrusion 1b provided on the case 1 so that θ2 ′> θ2 is established in advance at the stage of designing the knob 12 and the knob 12, the knob 12 is surely reached to the maximum scale position. Can be adjusted.

  Here, since θ2 is a constant angle as described above, θ2 ′ is set to be excessively large in order to cope with a large variation in angle between the center graduation position and the maximum graduation position as in the prior art. It is not necessary to set θ2 ′ to an angle obtained by adding the values of θ2 to dimensional error of case 1 and knob 12, combination accuracy error of case 1 and knob 12, and error of scale printing position. It is. It should be noted that the errors listed here need to be considered in the same way in the prior art.

  Furthermore, since it is not necessary to set θ2 ′ excessively large as described above, the positional relationship between the protrusion 12a of the knob 12 and the protrusion 1b of the case 1 can be determined so that the maximum scale side movable limit becomes small. As a result, it is possible to secure a large movable limit on the minimum graduation direction side, in which the variation becomes large because the bimetal operates at a position where the deformation amount of the bimetal is small, so that it is prevented from being in an unadjustable state at the minimum graduation position. Can do. From the above, compared to the prior art, the overcurrent relay according to the present invention prevents the adjustment from being impossible in the settling current adjustment range from the minimum scale to the maximum scale, and especially adjusts to the maximum scale position. Is possible. The positions of the protrusion 1b of the case 1 and the protrusion 12a of the knob 12 are not limited to the positions shown in FIGS. 4A and 5B, and are movable in a positional relationship that satisfies the above-described θ2 ′> θ1 ′. As long as the two protrusions are in contact with each other at the limit, they may be disposed anywhere on the case 1 and the knob 12. Further, the protrusion for determining the movable limit is not limited to the knob and the case as in the present invention, and may be provided anywhere.

  Here, the knob 12 is formed with two surfaces 12br and 12bl parallel to each other as shown in FIG. 3 (c), and its length L2 is equal to the radius L1 of the knob 12 as shown in FIG. 3 (c). It is configured to be approximately equal or have a length equal to or greater than the radius L1. This is because when the knob 12 is passed through the parts feeder in the production process of the thermal overcurrent relay, if the length of the face 12br and the face 12bl is short, these faces do not mesh well with the groove of the parts feeder. In order to prevent that 12 cannot maintain a fixed direction in the parts feeder, the lengths of the surface 12br and the surface 12bl are substantially equal to the radius L1 of the knob 12 or longer than the radius L1 as described above. Yes. This ensures that these surfaces engage with the grooves of the parts feeder so that the knob 12 can be supplied while being kept in a certain direction in the parts feeder.

  The radius r1 from the center of the knob 12 to the apex of the surface 12br (or surface 12bl) is larger than the radius r2 from the outer periphery of the protrusion 1b provided on the case 1 to the center of the adjustment screw 11 in FIG. Is also configured to be shorter. Further, in the production process of the thermal overcurrent relay, the heights of the two surfaces of the knob 12 that are in contact with the groove in the parts feeder are lowered. As described above, when the knob 12 is rotated, the protrusion 1b provided on the case 1 that defines the movable limit of the adjustment mechanism portion before the knob is fully rotated to the minimum scale position or the maximum scale position, and the knob. Therefore, when the knob is rotated, the surface provided on the knob is in contact with the case or the like as long as it is positioned between the minimum scale side movable limit and the maximum scale side movable limit. This prevents the adjustment mechanism from becoming inoperable due to the adjustment mechanism being in a movable limit.

It is a figure which shows the structure of a thermal type overcurrent relay. It is an enlarged view which shows the internal structure of a thermal type overcurrent relay. It is structural drawing which shows the structure of a knob. It is the structure figure which expanded the part to which a knob is attached among cases. It is an enlarged view of a knob part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Case, 1a Case side protrusion, 2 Cover, 5 Interlocking plate, 6 Temperature compensation bimetal, 12 Knob, 12b Knob side protrusion, 13 Rotating lever, 14 Normally open movable contact, 20 Reverse mechanism part, 21 Adjustment mechanism part

Claims (5)

Bimetal that bends in response to main circuit current, interlocking plate that transmits the displacement of this bimetal, reversing mechanism that trips when contacted with the interlocking plate and reverses the open / closed state of the contact, and moves the reversing mechanism The adjustment mechanism that can adjust the position where the open / close state of the contact is reversed, and the minimum scale, the central scale, which are displayed on the thermal overcurrent relay body and indicate the minimum, median, and maximum values of the settling current, respectively. In the thermal overcurrent relay with a scale display unit with the maximum scale, adjust the operating characteristics of each thermal overcurrent relay so that it operates within the range of operating characteristics specified by the standard In the electric tuning method of the thermal overcurrent relay,
Using a predetermined number of thermal overcurrent relays in which the electric adjustment work at the minimum graduation position and the central graduation position has been completed, while supplying a current in the range of 105% to 120% of the maximum value of the settling current, The angle of the adjustment mechanism is adjusted, and the angle from the center graduation position to the maximum graduation position of the adjustment mechanism where the thermal overcurrent relay trips is experimentally obtained as a sample angle. The first step of presetting the average value of the sample angle from the central scale position to the maximum scale position of the type overcurrent relay as the angle from the central scale position to the maximum scale position in the same rating,
A second step of determining the minimum graduation position and the central graduation position by operating characteristics of the thermal overcurrent relay;
A third step of determining the maximum scale position by giving an angle from the center scale position determined by the second step to the maximum scale position at the same rating preset by the first step;
A method for controlling a thermal overcurrent relay comprising:   The maximum scale position of the predetermined number of thermal overcurrent relays experimentally determined is that the minimum operating current value measured at a position where the angle in the maximum scale direction is gradually increased from the center scale position is 105% of the maximum scale value. It is a scale position used as the electric current value predetermined within the range of 120%, The electric tuning method of the thermal overcurrent relay of Claim 1 characterized by the above-mentioned.   The maximum scale position of the predetermined number of thermal overcurrent relays experimentally determined according to claim 1 is that the adjustment mechanism is tripped at least 120% of the maximum scale value from the center scale position to the maximum scale direction. In a state where the position is moved to a position where no change is made, after the energization is performed for a period of time until the amount of deformation of the bimetal is saturated within a range of 105% to 120% of the maximum scale value, the adjustment mechanism unit is moved again after the movement. It is a graduation position determined by moving from a position to the center graduation position side, and carrying out a forced trip manually, The electric adjustment method of the thermal overcurrent relay of Claim 1 characterized by the above-mentioned. Bimetal that bends in response to main circuit current, interlocking plate that transmits the displacement of this bimetal, reversing mechanism that trips when contacted with the interlocking plate and reverses the open / closed state of the contact, and moves the reversing mechanism The position where the open / close state of the contact is reversed can be adjusted, the adjustment mechanism part with the movable limit on each of the minimum scale direction adjustment side and the maximum scale direction adjustment side, the minimum value of the settling current displayed on the product body, A scale display unit with a minimum scale, a center scale, and a maximum scale, each indicating a median value and a maximum value;
In the thermal overcurrent relay with
The adjustment mechanism unit has a protrusion on the surface facing the knob case and the surface of the thermal overcurrent relay main body case facing the knob. However , the amount of rotation from the center scale position to the adjustment limit of the maximum scale direction adjustment side is wider than the amount of rotation from the position of the center scale to the adjustment limit of the adjustment mechanism section on the minimum scale direction adjustment side. The maximum graduation direction side movable limit is determined for each model rating in advance using a predetermined number of thermal overcurrent relays that have completed electric adjustment work at the minimum graduation position and the central graduation position. The angle from the center graduation position to the maximum graduation position is set considering the error .
Thermal overcurrent relay characterized by that. The knob is formed with two parallel surfaces, which are provided in order to install the knob without any delay in the production process of the thermal overcurrent relay, and the length of the surfaces is greater than the radius of the knob. And when the knob is rotated between the minimum scale side movable limit and the maximum scale side movable limit, the tip positions of the two surfaces provided on the knob set the movable limit of the adjustment mechanism section. The thermal overcurrent relay according to claim 4, wherein the thermal overcurrent relay according to claim 4 is spaced apart from a protrusion provided on a case to be defined by a predetermined gap.

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