JPS6242508Y2 - - Google Patents

Description

[Detailed Description of the Invention] Purpose of the Invention (Field of Industrial Application) This invention relates to a display control circuit in an overcurrent indicator.

(Prior Art) Conventionally, there have been various devices that operate a controlled object by driving a plunger by passing a predetermined current through a solenoid. In an overcurrent display device that operates the display member to a visible position, a bimetal is used to protect the solenoid from the current that flows continuously for a long time or exceeds a predetermined current value. was connected in series to the same solenoid. However, this method had the problem of lack of reliability because the bimetal involved mechanical movement.

The purpose of this invention is to solve the above-mentioned problems and provide a display control circuit for an overcurrent indicator that drives the solenoid more reliably and has high reliability.

Embodiment Hereinafter, an embodiment in which the display control circuit according to the present invention is embodied in an overcurrent passage display device will be described with reference to the drawings.

This overcurrent passage display device can be roughly divided into a current detection section A that detects overcurrent, a lifting mechanism H as a drive transmission mechanism section that performs lifting operation using the same drive mechanism B, and a display operation is performed by the same lifting mechanism H. It is composed of a display device I.

First, we will explain the current detection section A. This detection section controls the detection current transformer CT attached to the electric wire L and the transform current generated in the transformer CT when an overcurrent flows through the electric wire L. It is composed of a control circuit C that drives a rotary solenoid RS.

Next, the drive mechanism B will be explained.

When the rotary solenoid RS is energized, the output shaft P serving as a plunger is driven while accumulating a built-in return spring S, and when the excitation is released, the output shaft is rotated back to its original position by the return spring S. ing.

In FIG. 2, reference numeral 1 denotes a frame body (not shown) suspended below the wire clamping portion, which fixes the rotary solenoid RS. 2 is a disk-shaped drive plate attached to the output shaft P of the rotary solenoid RS, and 3 is an actuating member attached to the outer periphery of the drive plate 2, from which an actuating pawl 4 extending outward is formed to protrude. There is. and said rotary solenoid RS,
The drive plate 2 and the actuating member 3 constitute a drive mechanism B.

Next, the lifting mechanism H will be explained.

5 is the rotary solenoid in the frame 1;
A support plate section 6, which is provided upright to face the solenoid RS, is a lifting member whose base end is attached to a shaft 7 so as to be freely rotatable in both directions in the support plate section 5, and is located diagonally above the solenoid RS. (upper left in Figure 4). In the normal state, the lifting member 6 is locked by a stopper portion 1a provided at the lower part of the frame 1. The same lifting member 6
A guide hole 8 passing through both the upper and lower surfaces is provided at the distal end of the shaft, and a locking protrusion 9 is formed protruding from the base end, and a guide hole 8 with a slit 10a in the center is provided above the attachment portion of the shaft 7. A protrusion 10 is provided in a protruding manner.

11 has its base end engaged with the engagement protrusion 9, and is inserted into the guide hole 8 through the slit 10a of the guide protrusion 10.
It is a string-like member that is inserted through the holder and extends downward.
Note that the string-like member 11 in the slit 10a of the locking projection 9 and the guide projection 10 is fixed with an adhesive. Reference numeral 12 denotes a through hole formed through a side portion of the lifting member 6 near the proximal end.

As shown in FIG. 3, reference numeral 13 denotes an elastic clamping member having screws 14 attached to the opposite side of the lifting member 6 from the rotary solenoid RS. The side thereof is bent so as to protrude obliquely downward, and the tip thereof is bent horizontally at an acute angle toward the lifting member 6 and projects into the through hole 12 . And the locking member 13
As shown in FIG. 3b, the slanted portion 13a of the actuating member 3 rotates when the actuating member 3 is rotated from above.
The locking member 13 is pushed by the operating claw 4 against its elastic force and retreated toward the lifting member 6, and the bottom surface 16 of the tip end of the locking member 13 is removable from the operating claw 4 as shown in FIG. 3c. It's summery. A lifting mechanism H is constituted by the lifting member 6, the string member 11, and the locking member.

Next, the display device I will be explained.

In FIG. 1, reference numeral 18 is a bottomed annular display tube made of colorless and transparent synthetic resin or glass, which is provided below the frame 1, and is screwed into the upper end opening in a watertight manner. Transparent lid 19 made of synthetic resin
20 bolts (see Fig. 2) are attached to the frame body 1 via. The upper center surface of the lid 19 is formed with a funnel-shaped recess, and the lower center surface is formed with a protrusion 21, with an insertion hole 22 extending vertically through the protrusion 21.

Reference numeral 23 is a black hook member screwed onto the outer periphery of the lower end of the display tube 18, and a rotating fitting groove 24 is recessed in the upper end of the hook member. The lower end of a cylindrical main body case 25 whose upper end is fitted into the lower surface of the electric wire clamp (not shown) is fitted into the fitting groove 24 .

Reference numeral 26 denotes a cylindrical reflective member made of aluminum or the like and made of silvery white and fitted onto the inner periphery of the display tube 18 .
Reference numerals 27 and 28 indicate a colored fluid with a low specific gravity and high viscosity (red in this example), and a transparent fluid with a high specific gravity and low viscosity (colorless in this example), which are stored in required amounts in upper and lower layers in the display tube 18, respectively. ).

Reference numeral 31 denotes a valve body as an indicator valve that is always located within the fluids 27 and 28, and is inserted into the insertion hole 2 of the lid body 19.
It is suspended by the string-like member 11 that is inserted into the inside. The valve body 31 is housed inside the reflection member 26 so as to be vertically movable with a small gap therebetween. Also, the specific gravity of this valve body 31 is the same as that of the colored fluid 2.
7 and smaller than the transparent fluid 28, so as to leave a gap between the valve body 31 and the bottom 18a of the display tube 18, which also serves as a display window, so that the entire lower surface of the valve body 31 is submerged in the transparent fluid 28 in a normal state. It is located in

Next, to explain the operation of the overcurrent passage display device configured as above, when an overcurrent exceeding a set value passes through the electric wire L, a transformer current is generated by the transformer CT, and the control circuit C generates a transformed current. The output shaft P of the rotary solenoid RS is rotated 45 degrees while resisting the elastic force of the built-in return spring S.

At this time, the actuating member 3 is rotated in the direction of the arrow through the driving plate 2 to the positions of FIG. 4a to FIG. 4b. The operating claw 4 of the operating member 3 rotates from above.
pushes the diagonal portion 13a of the locking member 13 toward the lifting member while resisting its elastic force (see Figure 3b), then releases the pressure on the diagonal portion 13a and rotates it to its lower position. (See Figure 4b). The slanted portion 13a whose pressure has been released returns to its original position by its own elastic force, as shown in FIG. 3c.

Note that the operation of the actuating member 3 due to the rotation of the rotary solenoid RS up to this point is instantaneously performed.

Then, the rotary solenoid has finished rotating.
The output shaft P of the RS starts to rotate back in the opposite direction, that is, in the counter-driving direction, by the built-in return spring S.

As a result, when the operating claw 4 rotates to the positions c and c in FIG. The shaped member 11 is rolled up. Therefore, the valve body 31 of the display device I is affected by its gravity and the fluid 2.
The string-like portion 11 while resisting the viscous resistance of 8 and 27
is pulled upwards through the And the valve body 31
is entirely transferred into the colored fluid 27.

Further, when the actuating pawl 4 is rotated in the counter-driving direction, the actuating pawl 4 completes the lifting operation of the valve body 31 and separates from the lower surface of the distal end of the locking member 13, as shown in FIG. 4d.

After the operating pawl 4 is released, the lifting member 6 instantaneously returns to rotation in the direction of the arrow in FIG. 4e until it is stopped by the stopper portion 1a of the frame 1 due to its own weight.

On the other hand, when the operating claw 4 is detached from the bottom surface 16 of the tip of the clamping member 13, the valve body 31 of the display device I is positioned above the colored fluid 27 to display an overcurrent passage display, and the bottom 18a of the display tube 18 colored fluid through 2
7 colors can be visually recognized.

At this time, the lifting member 6 instantaneously rotates back and locks with the stopper portion 1a as described above, and its tip is positioned downward, so that no load is applied to the string member 11 as shown in FIG. 4e. It bends upward between the guide hole 8 and the slit 10a. Then, the valve element 31 of the display device I begins to descend due to its own weight, and is delayed by the viscous resistance of the colored fluid 27, and after a predetermined time, the entire lower surface of the valve element 31 is submerged in contact with the transparent fluid 28. However, it returns to normal display.

Next, the rotary solenoid of the drive mechanism B
The control circuit C that drives and controls RS will be explained in detail.

In FIG. 5, the current transformer CT arranged for the electric wire L has both terminals connected to the chiyoke coil 4.
A full wave rectifier 43 is connected via 1 and 42.
A surge absorber 44 is connected between both terminals.

Between the positive and negative terminals of the full-wave rectifier 43, the b contact Xb of the relay X, the thyristor SCR, and the excitation coil of the relay X are connected in series. The thyristor SCR has an anode connected to the b contact Xb and a cathode connected to the excitation coil of the relay X. A voltage setting resistor R1 and a smoothing capacitor C1 for smoothing the pulsating current output from the full-wave rectifier 43 are connected in parallel between the anode terminal of the thyristor SCR and the negative terminal of the full-wave rectifier 43. . Similarly, resistors R4 and R5 for gate voltage setting are connected in series between the anode terminal of the thyristor SCR and the negative terminal of the full-wave rectifier 43, and the thyristor is connected to the negative terminal of the resistor R4.
The SCR gate terminal is connected.

The resistor R1 is set to be sufficiently smaller than the resistors R4 and R5. Further, a capacitor C2 is connected between the cathode and gate of the thyristor SCR, and when the contact Xb is opened, it absorbs surges and external lightning surges to prevent erroneous firing.

A diode D2 is connected in series between both terminals of the excitation coil of the relay X with its anode on the negative side, and is designed to absorb the surge voltage generated when the relay X is de-energized.

The positive terminal of the b contact Xb and the full wave rectifier 4
Between the negative side of 3 and the a contact of the relay
Xa, a positive polarity thermistor 45, and a rotary solenoid RS are connected in series, and a Zener diode ZD1 is connected in parallel between both terminals of the a contact Xa with its cathode on the positive side. A Zener diode ZD2 as a voltage-dependent semiconductor is connected in parallel with the series circuit with the rotary solenoid RS with its anode on the negative side. The positive thermistor 45 and the Zener diode ZD2 constitute a protection circuit for the rotary solenoid RS. Further, a series circuit consisting of a resistor R3 and a diode D3 is connected between the negative terminal of the a-contact Xa and the positive terminal of the relay X as a self-holding circuit.

Next, the operation of this control circuit C will be explained.

Now, when a normal load current is flowing through the electric wire L, a small amount of alternating current is output from the current transformer CT, and after this alternating current is rectified by the full-wave rectifier 43, most of this current is transferred to the resistor R1. Consumed at At this time, since the anode voltage and gate voltage applied to the thyristor SCR are very small, the thyristor SCR is in an off state.

In this state, if an overcurrent flows through the electric wire L, a transformed current is output from the current transformer CT, and this transformed current is rectified by the full-wave rectifier 43 and then the b-contact
It flows through resistors R1, R4, and R5 via Xb and charges capacitor C1.
Based on R4 and R5, a sufficient anode voltage and gate voltage are applied to the thyristor SCR, so that the thyristor SCR is turned on and becomes conductive.
When relay X is excited, the b-contact Xb is opened and the a-contact Xa is closed at that moment.

At this time, after the b contact Xb is opened, the a contact Xa
It takes 10 to 20 m/sec to close the circuit, and during that time both contacts are open, so a high voltage is generated at the positive terminal of the full-wave rectifier 43.
Zener diode ZD1 breaks down and becomes conductive, supplying exciting current to rotary solenoid RS and supplying exciting current to relay X via resistor R3 and diode D3.
When the a contact Xa is closed, most of the output current of the full-wave rectifier 43 flows to the rotary solenoid RS, which is sufficiently excited to rotate its output shaft P by a predetermined angle. A part of it flows to relay
Self-maintains Xa in a closed circuit state. The operation described above, from when the thyristor SCR is turned on until the a contact Xa is closed, is as follows: When the thyristor SCR is turned on and the b contact Xb is opened at the same time as the relay X is energized, the At this point, the current output from the full-wave rectifier 43 to the relay C1 supplies anode current to thyristor SCR to keep relay X energized.

When the current flowing through the wire L returns to its normal state from this state, the excitation current flowing through the relay X is cut off, the a contact Xa is opened, and the b contact Xb
is closed, the excitation current flowing through the rotary solenoid RS is cut off, and the excitation current is released. When the rotary solenoid RS is de-energized, the output shaft P of the rotary solenoid RS
It is rotated back to its original position by a return spring S installed in the overcurrent display device, and based on this operation, the display device I of this overcurrent display device performs the display operation as described above.

In addition, in this circuit C, if an overcurrent flows through the electric wire L for a long time and the excitation current continues to flow through the rotary solenoid RS, the resistance value of the positive thermistor 45 increases relative to it. . As the resistance value of the thermistor 45 increases,
When the potential between the terminals of the Zener diode ZD2 rises and exceeds the predetermined potential, the diode ZD
2 is made conductive.

When the Zener diode ZD2 is made conductive, the excitation current of the rotary solenoid RS is cut off. Therefore, the rotary solenoid RS will not be burned out by the excitation current.

In the above embodiment, the solenoid RS was designed to allow a DC excitation current to flow through it, but an AC excitation current may also be used. In this case, two Zener diodes ZD3 and ZD4 are connected as shown in Figure 6. However, it is sufficient to connect the positive polarity thermistor 45 and the rotary solenoid RS in parallel. moreover,
If it is necessary to completely cut off the power supply path to the rotary solenoid RS, connect a resistor R6 and a keep relay RXk in series to a Zener diode ZD5 as shown in Figure 7, so that the keep relay RXk is energized. When the relay RXk's normally open contact Xk is held open, the solenoid
The power supply to RS may be completely cut off.

Effects As detailed above, this invention reliably protects the solenoid from current that continues to flow in the solenoid for a long time or from current that flows in excess of the permissible value. or,
At the initial stage of operation, the switching element is in the on state and the relay During a short period of time until the breakdown occurs and relay X is energized, relay X is kept energized by the discharge current from capacitor C1.

Then, after the b contact Xb is opened, the a contact Xa
Zener diode ZD1 breaks down even if both contacts are open for a short time until the relay is closed, so the solenoid is driven reliably, and then the a contact Xa is activated by the self-holding circuit of relay , the solenoid can be kept energized and stable display operation can be obtained, which is an excellent effect.

[Brief explanation of drawings]

Fig. 1 is an overall schematic diagram of an overcurrent passing device embodying this invention, Fig. 2 is a plan view of the drive mechanism, and Figs. 3 a to c are explanations showing the linked operation of the actuating member and the locking member. Figures 4a to 4e are explanatory diagrams showing each state of the drive transmission mechanism, Figure 5 is an electrical circuit diagram of the control circuit, and Figures 6 and 7 are overcurrent diagrams showing other examples of this invention. FIG. 3 is an electrical circuit diagram of a display control circuit of the display device. Positive polarity thermistor 45, Zener diode
ZD2, rotary solenoid RS.

Claims (1)

[Claim for Utility Model Registration] A rectifier 43 disposed in a current transformer CT attached to the distribution line L is connected, and a contact between the positive terminal and the negative terminal of the rectifier 43 is connected to the B contact of the relay X. A series circuit consisting of a switching element SCR operated by a voltage higher than the voltage and a relay X, a capacitor C1 connected between the negative terminal of its b contact A contact Xa of relay X, positive thermistor 45, solenoid
RS, a Zener diode ZD1 connected in parallel to the a-contact Xa, and the a-contact to maintain the relay X by itself.
Consists of a self-holding circuit D3, R2 connected between the negative terminal of Xa and the positive terminal of the relay X, and a Zener diode ZD2 connected in parallel to both terminals of the series circuit of the positive thermistor 45 and solenoid RS. Display control circuit for overcurrent indicator.