JPH0136656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for an undervoltage tripping device, and more particularly to a control circuit for controlling a current flowing through a tripping coil provided in the tripping device.

For example, in a circuit breaker, an undervoltage tripping device is a device that trips the circuit breaker when the voltage of the electrical circuit in which the circuit breaker is inserted falls below a certain predetermined value, that is, when the electrical circuit voltage is insufficient. It is.

FIG. 1 is a diagram showing an example of such an undervoltage tripping device. The structure and operation of the undervoltage tripping device, which is the premise of the present invention, will first be described with reference to FIG.

The undervoltage tripping device 1 is provided with a fixed iron core 2, and a movable iron core 3 is provided so that one end surface of the fixed iron core 2 corresponds to the end surface of the fixed iron core 2. An undervoltage tripping coil (UVT) is installed around the fixed core 2 and the movable core 3 along the central axes of the two cores.
4 is wrapped. The fixed iron core 2 and the undervoltage tripping coil are both fixed to the base body 5. Therefore, depending on the excitation strength of the tripping coil 4, the movable iron core 3
is attracted to or released from the fixed iron core 2. That is, the movable iron core 3 moves from side to side along the inner diameter of the undervoltage tripping coil 4.

The other end of the movable core 3 is rotatably held by a shaft 7 approximately in the longitudinal center of the movable core holder 6. One end of the movable core holder 6 is rotatably supported by a shaft 9 on a movable core support frame 8 that is attached and fixed to the base 5, and an undervoltage tripping lever 10 is mounted on the other end. 1
1 is also rotatably connected. Further, the trip lever 10 is connected to a trip lever of a circuit breaker (not shown).

Normally, when the voltage of the electrical circuit in which the circuit breaker is inserted exceeds a predetermined value, the movable core 3 is attracted toward the fixed core 2 by the undervoltage tripping coil 4. There is. That is, the movable core is held in the state shown by the solid line 3a in FIG. This is because the undervoltage tripping coil 4 is supplied with the current necessary to maintain the movable core 3 in the attracted state shown in 3a. If the voltage of the electric circuit falls below a predetermined value, the current flowing through the undervoltage tripping coil 4 decreases, and the undervoltage tripping coil 4 maintains the movable iron core 3 in the attracted state shown by 3a. Therefore, the movable core 3 is opened as shown by the dotted line 3b in FIG. When the movable core 3 is opened, that is, moved to the left in FIG. 1, the movable core holder 6, which is connected to the movable core 3 by the shaft 7, rotates clockwise about the shaft 9. As a result, the trip lever 10 connected to the movable core holder 6 by the shaft 11 moves to the left, and as a result, a trip lever (not shown) acts to trip the circuit breaker.

In other words, in general, undervoltage tripping devices for circuit breakers are such that when the line voltage exceeds a predetermined value, the tripping coil 4 of the device is in a suction state and the circuit breaker can be closed; In this case, it is not possible to maintain the suction state of the tripping coil 4,
The tripping coil 4 opens the movable core 3 to trip the closed circuit breaker or prevent the closed circuit breaker from closing. In such a movable core automatic attraction type undervoltage tripping device, a large attraction force must be generated when the undervoltage tripping coil 4 attracts the open movable core 3.
This requires a relatively large ampere turn in the undervoltage trip coil 4. Therefore, in the conventional movable core automatic attraction type undervoltage tripping device, the undervoltage tripping coil becomes large, the undervoltage tripping device occupies a large space, and the overall size cannot be reduced.

Therefore, the object of the present invention is to control the current flowing through the undervoltage tripping coil to reduce the size of the undervoltage tripping coil.

To put it simply, this invention is a control circuit for an undervoltage tripping device, and the present invention is a control circuit for an undervoltage tripping device, in which the undervoltage tripping coil automatically draws the movable iron core for the necessary minimum amount of time. time, thereby limiting the ampacity of the undervoltage trip coil to that amount of ampacity necessary for the undervoltage trip coil to maintain the movable core in its attracted state;
This is a control circuit for an undervoltage tripping device that makes it possible to use a small undervoltage tripping coil.

The above-mentioned objects and other objects and features of the present invention will become more specific and clear from the description of one embodiment with reference to the following drawings.

FIG. 2 shows an embodiment of the present invention. In FIG. 2, a tripping control circuit 20 is connected to an electric circuit 21 to an undervoltage tripping coil 4 of the tripping device.
Current is supplied through. Tripping control circuit 20
is structured as follows. A primary winding 23 of a transformer 22 is inserted into the electric line 21, and two secondary windings 24 and 25 are provided on the secondary side of the transformer 22. Rectifier circuits 26 and 27 are connected to the secondary windings 24 and 25, respectively, and direct current is obtained from these two rectifier circuits 26 and 27. The output to the rectifier circuit 26 is, for example, a DC voltage.
The current is about 600 mA at 160 V, and the output of the rectifier circuit 27 is, for example, about 100 mA at a DC voltage of 30 V. In this way, the rectifier circuit 26 is connected to the rectifier circuit 2.
The difference in output compared to 7 is that the rectifier circuit 26 acts as a power source to flow a suction current to the undervoltage tripping coil 4, and the rectifier circuit 27 acts as a power source to flow a holding current to the undervoltage tripping coil 4. This is because it is made to work.

The undervoltage tripping coil 4 is connected to the rectifier circuit 26 via a relay contact 28 . In this embodiment, a plurality of series-parallel contacts are used as the relay contacts 28. This is because contacts with a small current capacity are used, thereby reducing the overall size. Of course, it goes without saying that it does not matter if it is only one point of contact.

The undervoltage tripping coil 4 is connected to the rectifier circuit 27 via a resistor 29, a variable resistor 30, and a diode 31 connected in series. Here resistance 29
For example, 10W, 10Ω, variable resistor 30 is 10W,
It has a capacity of 300Ω and adjusts the current flowing to the undervoltage tripping coil 4. Diode 31 has a switching effect. That is, the rectifier circuit 26
When the current from the rectifier circuit 27 is flowing to the undervoltage tripping coil 4, the current flowing from the rectifier circuit 27 to the tripping coil 4 is stopped. In addition, the rectifier circuit 2
6 is prevented from flowing back toward the variable resistor 30. Variable resistor 30, diode 31
A series connection of an automatic suction start voltage setting resistor 32, an automatic suction start relay coil 33, and a switch 34 are connected in parallel to the series connection of the undervoltage tripping coil 4. The automatic suction start voltage setting resistor 32 has a capacity of, for example, 2W and 1kΩ.
The resistor 32, relay coil 33 and switch 3
4 constitutes an automatic suction start voltage setting circuit,
When the voltage of the electric line 21 exceeds a predetermined value, the relay coil 33 is set to be activated by the current from the rectifier circuit 27.

Furthermore, in this embodiment, a resistor 35 (for example, 10 W,
150Ω) and a capacitor 36 (for example, 2200 μF) are connected in series to form a trip delay circuit.

Now, in the circuit configuration shown in Figure 2, switch 3
4 is the movable core 3 of the tripping device 1 in FIG.
This is a switch that is switched in response to whether the undervoltage tripping coil 4 is attracted or released. For example, as shown in FIG. 3, this switch is connected to the movable core 3 of the tripping device 1, and is activated by the actuator 13 in response to the movement of the movable core holder 6, which moves in accordance with the movement of the movable core 3. Limit switch 34 to which the switching button 14 is switched
It can be configured by using a. In addition, the second
The switch 34 shown in the figure is not limited to the limit switch 34a shown in FIG. It does not matter if it is a switch or any other switch.

Further, the relay coil 33 in FIG. 2 is a coil that controls the opening and closing of the relay contact 28, and only when a predetermined current is flowing through the relay coil 33, the normally open relay contact 28 is turned on by the coil 33. turned on.

Next, the operation of the tripping device and the tripping control circuit will be explained with reference to FIGS. 2, 3, and 4.

When the movable core 3 of the tripping device 1 is in the open state, the switch 34 is on. Therefore, at this time, current is flowing through the automatic suction start voltage setting circuit comprised of the rectifier circuit 27, the resistor 29, the automatic suction start voltage setting resistor 32, the relay coil 33, and the switch 34. Then, when the current flowing through this circuit exceeds a certain value, that is, when the voltage of the electric line 21 exceeds a predetermined value, the relay coil 33 operates to turn on the relay contact 28.

Next, in the circuit composed of the rectifier circuit 26, the relay contact 28, and the undervoltage tripping coil 4,
As described above, when the normally open relay contact 28 is turned on by the relay coil 33, current flows from the rectifier circuit 26 to the undervoltage tripping coil 4 via the relay contact 28. At this time, the current flowing from the rectifier circuit 26 is a relatively large current as described above, and this current allows the undervoltage tripping coil 4 to attract the movable iron core 3. When the movable iron core 3 is switched from the open state to the attracted state by the undervoltage tripping coil 4, the limit switch 34a shown in FIG. 3 is also switched accordingly. That is, this is the switching of switch 34 in FIG. Therefore, the switch 34 is switched from the on state to the off state. Then, no current flows through the automatic suction start voltage setting circuit, that is, the relay coil 33. As a result, the relay contact 28, which had been kept in the on state by the relay coil 33, returns to its original off state. By turning off the relay contact 28, the supply of large attraction current from the rectifier circuit 26 to the undervoltage tripping coil 4 is stopped, and the undervoltage tripping coil 4 completes attraction of the movable iron core 3.
Thereafter, a relatively small holding current flows from the rectifier circuit 27 to the undervoltage tripping coil 4 via the variable resistor 30, diode 31, etc. This current allows the undervoltage tripping coil 4 to continue to maintain the attracted state of the movable iron core 3.

FIG. 4 is a diagram showing changes in the current i flowing through the undervoltage tripping coil 4 in the above series of operations. In FIG. 4, the horizontal axis shows time, and the vertical axis shows changes in the current i flowing through the undervoltage tripping coil 4. In FIG. 4, at time OP, the movable core 3 of the tripping device 1 is in an open state, and the switch 34 is in an on state. Then, when time reaches P, the voltage of the electric line 21 exceeds a predetermined value, the relay coil 33 turns on the relay contact 28, and a large current flows from the rectifier circuit 26 to the undervoltage tripping coil 4. The large current flowing at this time, that is, the attraction current i ₁ is, for example, about 600 mA. When the attraction current i ₁ flows, the movable iron core 3 is immediately switched from the open state to the attraction state by the undervoltage tripping coil 4, and accordingly, the switch 34 is switched as described above, and the attraction current i ₁ also flows. It disappears. That is, the time period PQ is a very short time period. Even if an overcurrent exceeding the rating flows through the undervoltage tripping coil 4 for such a short period of time PQ, there will be no adverse effects such as burnout or destruction of the coil 4. After that, when the voltage of the electric circuit 21 returns to the rated voltage, the holding current i ₂ continues to flow through the undervoltage tripping coil 4. This holding current _i2 is, for example, approximately 100m
It is A. In addition, in Fig. 4, time S is electric line 2.
This is the point at which the voltage No. 1 reaches the rated voltage (generally higher than the predetermined voltage determined as the voltage at which suction starts).

After that, if the current supplied from the rectifier circuit 27 to the undervoltage tripping coil 4 decreases due to voltage fluctuations in the electric line 21, that is, due to the voltage of the electric line 21 decreasing below a predetermined value, the undervoltage tripping coil 4 is activated. The removal coil 4 cannot maintain the suction state and releases the movable iron core 3 from the suction state. A movable core holder 6 connected to the movable core 3 by this,
The tripping lever 10 operates and the closed circuit breaker is tripped. In addition, the switch 34 is turned on again accordingly.

In each of the above cases, the switch 34 is turned on/off.
Of course, depending on the circuit configuration, the OFF state can be reversed in some cases.

In this embodiment, a trip delay circuit composed of a resistor 35 and a capacitor 36 is provided in parallel with the rectifier circuit 27, so that when the voltage of the electric line 21 drops below a predetermined value, the rectifier circuit 27
Even if the output current decreases, the decrease does not immediately act on the undervoltage tripping coil 4. because,
When the current output from the rectifier circuit 27 decreases, the charging current that has been charged in the capacitor 36 up to that point is discharged by the amount that is insufficient, and the change in the current flowing into the undervoltage tripping coil 4 is delayed by the discharge time of the capacitor 36. It is from. An advantage of providing such a delay circuit is that the undervoltage tripping coil 4 does not respond when the voltage fluctuation of the electric line 21 is instantaneous. And the circuit breaker can be controlled more stably and practically.

As described above, according to the present invention, the control of the current supplied to the undervoltage tripping coil is made responsive to the state of the movable core that the undervoltage tripping coil attracts and releases. The relatively large movable core attraction current flowing through the movable core can be suppressed to the minimum time required for attraction, and the undervoltage tripping coil can be downsized. In addition, when the movable iron core is held, the undervoltage tripping coil is not affected by the voltage of other circuits, such as the automatic suction start voltage setting circuit, and the undervoltage tripping coil operates accurately and the tripping device is activated. It also has the effect of making the tripping operation more reliable.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an undervoltage tripping device. FIG. 2 is a circuit diagram showing an embodiment of the present invention. Figure 3 shows the undervoltage tripping device and the
It is a figure of one Example which shows the relationship with the switch in a figure. FIG. 4 is a diagram showing the relationship between the current supplied to the undervoltage tripping coil and time. In the figure, 1 is a tripping device, 3 and 3' are movable iron cores, 4 is an undervoltage tripping coil, 20 is an undervoltage tripping control circuit, 21 is an electric circuit, 22 is a transformer, 2
4 and 25 are secondary windings, 26 and 27 are rectifier circuits,
28 is a relay contact, 30 is a variable resistor, 33 is a relay coil, 34 is a switch, 34a is a limit switch, and 36 is a delay capacitor.

Claims (1)

[Scope of Claims] 1. A movable iron core connected to a tripping lever is attracted when the voltage of an electric circuit exceeds a predetermined value, and a trigger that releases the movable iron core when the voltage of the electric circuit becomes lower than a predetermined value. A control circuit for an undervoltage tripping device equipped with a disconnection coil, which turns off (or on) when the movable core is in a attracted state.
a switch means which is transformer-coupled to the electric line and is turned on (or off) in an open state, and when the electric line voltage exceeds the predetermined value while the switch means is on (off), the tripping coil is turned on; a first current supply means for supplying a first magnitude of current with a strength necessary to attract the movable iron core; A second current supply means is provided for supplying a current of a second magnitude necessary to maintain the attracted state of the movable iron core through the detachment coil, and the current of the second magnitude is normally used to supply the current of the second magnitude. The switching means is turned off (on) by the detachment coil holding the movable iron core in a attracted state, and when the voltage of the electric circuit becomes equal to or less than the predetermined value, the second magnitude is increased. When the current decreases and the tripping coil opens the movable iron core, the switching means is turned on (off), and when the voltage of the electric circuit recovers and exceeds the predetermined value again, the switching means is turned on (off). 1. A control circuit for an undervoltage tripping device, wherein a current having a magnitude of 1 flows and the movable iron core is attracted by the tripping coil. 2. The first current supply means includes: a rectifier for rectifying the secondary winding of the transformer coupled to the transformer and the output current from the winding; when the voltage of the electric circuit exceeds the predetermined value; 2. The undervoltage according to claim 1, further comprising: a suction start relay that operates to operate, and a relay contact that is inserted between the rectifying means and the tripping coil and turns on in response to the relay. Control circuit for tripping device. 3. The second current supply means includes: a rectifier for rectifying the secondary winding of the transformer coupled to the transformer and the output current from the winding; and a rectifier connected to the rectifier to adjust the output current. 3. A control circuit for an undervoltage tripping device according to claim 1, further comprising a variable resistor for controlling the undervoltage tripping device. 4. A patent claim characterized in that the second current supply means is provided with a delay circuit in parallel with the rectification means for delaying fluctuations in the output current of the rectification means and transmitting the same to the tripping coil. A control circuit for an undervoltage tripping device according to item 3.