JPH0591792A - Control power unit for thyristor leonard - Google Patents

Abstract

PURPOSE:To maintain the voltage of a control power source within a prescribed rage so as to supply stable control power by automatically switching the tap of a tapped transformer for supplying control power connected to the secondary side of a transformer for supplying power to a main circuit to an adequate value by operating a voltage relay which detects the secondaryside voltage of the transformer for supplying power to the main circuit. CONSTITUTION:When a DC motor 1 is started and a voltage drop occurs in a transformer 3 for supplying power to a main circuit, a voltage relay 7 connected to a control circuit feeder branched from the secondary side of the transformer 3 detects the drop in the secondary side voltage of the transformer 3 from a prescribed value and starts to operate. The voltage of a control power source is maintained within a prescribed range by inputting an operating signal from the relay 7 to a tap switching circuit 8 and automatically switching the tap of a tapped transformer 6 for supplying control power to an adequate value. Therefore, even when a voltage drop occurs in the transformer 3 due to the actuation of the motor 1, stable control power can be supplied to various kinds of control circuits without giving any influence to a control power source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control power supply device for a thyristor leonard, and particularly to a voltage drop of a main circuit power transformer for various control circuits even when the main circuit power transformer has a voltage drop. The present invention relates to a thyristor leonard control power supply device capable of supplying a stable control power supply by preventing the influence of the above.

[0002]

2. Description of the Related Art Generally, it is ideal that the main circuit power source and the control power source of a thyristor leonard are supplied as separate power sources. In many cases, the control power is supplied by further branching.

By the way, in a thyristor leonard for starting a heavy load device (for example, a DC motor) that requires a large starting torque, the starting torque of the DC motor is 200%.
Alternatively, it is 250% or the like, and there is no problem when the power supply capacity of the main circuit power supply transformer is very large.

However, when the power supply capacity of the main circuit power supply transformer is small, a considerable voltage drop occurs in the main circuit power supply transformer when the DC motor is started. And at this time,
Since the control power is supplied by branching from the main circuit power, the voltage drop of the main circuit power transformer will spread to the control power and adversely affect the field control circuit and sequence control circuit of the DC motor. ..

[0005]

As described above, in the prior art, when a voltage drop occurs in the main circuit power supply transformer, the voltage drop of the main circuit power supply transformer spreads to various control circuits and stabilizes. There is a problem that the control power cannot be supplied.

An object of the present invention is to prevent the voltage drop of the main circuit power transformer from spreading to various control circuits and supply a stable control power even when the main circuit power transformer has a voltage drop. It is an object of the present invention to provide an extremely reliable thyristor Leonard control power supply device which can be manufactured.

[0007]

In order to achieve the above-mentioned object, a thyristor leonard control power supply device of the present invention comprises:
Control in which the primary side is branched from the secondary side of the main circuit power transformer for supplying the main circuit power to the thyristor leonard that starts the load, and its primary side is connected, and the load control circuit is connected to the secondary side When inputting the secondary side voltage of the power circuit tap transformer and the main circuit power source transformer and detecting that the secondary side voltage drops below a predetermined value, the voltage relay that operates and the voltage relay that operates, And a tap switching circuit for switching the taps of the control power supply tapped transformer so as to keep the voltage of the control power supply within a predetermined range. Here, in particular, the load is a DC motor, and the control circuit is a field control circuit and a sequence control circuit of the DC motor.

[0008]

Therefore, in the thyristor leonard control power supply device of the present invention, the load is activated, a voltage drop occurs in the main circuit power supply transformer, the secondary side voltage thereof drops below a predetermined value, and the voltage relay operates. When operated, the taps of the transformer with taps for control power supply are automatically switched to appropriate values by the tap switching circuit, and the voltage of the control power supply is maintained within a predetermined range. As a result, even if a voltage drop occurs in the main circuit power transformer, stable control power can be supplied to various control circuits without affecting the control power.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a circuit diagram showing an example of the overall configuration of a thyristor leonard control power supply device according to the present invention.

That is, as shown in FIG. 1, the thyristor leonard control power supply device of the present embodiment is a main circuit power supply transformer for supplying a main circuit power supply to a thyristor leonard 2 which starts a DC motor 1 as a load. A control power tapped transformer 6 in which the primary side is branched from the secondary side of 3, and the field control circuit 4 and the sequence control circuit 5 of the DC motor 1 are connected to the secondary side, and a tapped transformer 6 for control power supply, and a main circuit. When the secondary voltage of the power transformer 3 is input and it is detected that the secondary voltage has dropped to a predetermined value or less, the voltage relay 7 that operates and the voltage of the control power supply that operates when the voltage relay 7 operates It comprises a tap switching circuit 8 for switching the taps of the transformer 6 with taps for the control power source so as to keep the range. Next, the operation of the thyristor leonard control power supply device of the present embodiment configured as described above will be described.

In FIG. 1, when the DC motor 1 is started and a voltage drop occurs in the main circuit power transformer 3, the voltage relay 7 is connected to the control circuit feeder branched from the secondary side of the main circuit power transformer 3. However, it operates by detecting that the secondary side voltage has dropped below a predetermined value. When the operation signal from the voltage relay 7 is input to the tap switching circuit 8, the taps of the transformer 6 with taps for control power supply are automatically switched by the tap switching circuit 8 to a proper value, and the tap of the control power supply is changed. The voltage is kept within a predetermined range.

As a result, when the DC motor 1 is started,
Even if a voltage drop occurs in the main circuit power supply transformer 3, stable control power can be supplied to various control circuits without affecting the control power. Also, when selecting the capacity of the main circuit power supply transformer 3, it is not necessary to make a selection in consideration of the voltage drop at the time of starting the DC motor 1, and it is sufficient to select a capacity commensurate with the applicable DC motor 1. The capacity of the main circuit power transformer 3 can be reduced.

As described above, the control power supply device for the thyristor leonard of this embodiment is the secondary of the main circuit power supply transformer 3 for supplying the main circuit power supply to the thyristor leonard 2 which starts the DC motor 1 which is the load. Side is branched and the primary side is connected, and the DC motor 1 is connected to the secondary side.
The secondary voltage of the control power tap transformer 6 to which the field control circuit 4 and the sequence control circuit 5 are connected and the secondary voltage of the main circuit power transformer 3 are input, and the secondary voltage has dropped to a predetermined value or less. A voltage relay 7 that operates when it detects that
When the voltage relay 7 operates, it is configured with a tap switching circuit 8 that switches the taps of the control power supply tapped transformer 6 so as to keep the voltage of the control power supply within a predetermined range.

Therefore, even if the main circuit power supply transformer 3 causes a voltage drop due to the activation of the DC motor 1, the main circuits for the various control circuits such as the field control circuit 4 and the sequence control circuit 5 of the DC motor 1 will be described. Power transformer 3
It is possible to prevent the ripple of the voltage drop and to supply an extremely stable control power supply. Also, when selecting the capacity of the main circuit power supply transformer 3, it is not necessary to make a selection in consideration of the voltage drop at the time of starting the DC motor 1, and it is sufficient to select a capacity commensurate with the applicable DC motor 1. The capacity of the main circuit power supply transformer 3 can be reduced, and an economical effect can be obtained.

In the above embodiment, the load is the DC motor and the control circuit is the field control circuit and the sequence control circuit of the DC motor. However, the present invention is not limited to this, and other loads and the control circuit thereof may be used. Even in some cases, the present invention is applied in the same manner, and the same effect as the above case can be obtained.

[0016]

As described above, according to the present invention, the primary side is branched from the secondary side of the main circuit power source transformer for supplying the main circuit power source to the thyristor leonard for starting the load. At the same time, the secondary side voltage of the main circuit power source transformer and the tapped transformer for control power supply, to which the load control circuit was connected, was input to the secondary side, and the secondary side voltage dropped below the specified value. When the voltage relay operates, the voltage relay operates, and when the voltage relay operates, the tap switching circuit that switches the tap of the transformer for tapping the control power supply so as to keep the voltage of the control power supply within a predetermined range. Therefore, even if the main circuit power supply transformer has a voltage drop, it is possible to prevent the ripple of the voltage drop of the main circuit power supply transformer to various control circuits and supply a stable control power supply. Control power supply reliable thyristor Leonard can be provided.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a control power supply device for a thyristor leonard according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... DC motor, 2 ... Thyristor Leonard, 3 ... Main circuit power transformer, 4 ... Field control circuit of DC motor 1, 5 ...
Sequence control circuit, 6 ... Transformer with tap for control power supply,
7 ... Voltage relay, 8 ... Tap switching circuit.

Claims (2)

[Claims] 1. A main circuit power transformer for supplying main circuit power to a thyristor leonard for activating a load, a primary side of which is branched from a secondary side of the main circuit power transformer, and the secondary side controls the load. A tapped transformer for control power supply to which a circuit is connected, and a voltage relay that operates when the secondary side voltage of the main circuit power supply transformer is input and it is detected that the secondary side voltage has dropped below a predetermined value. When the voltage relay operates, a tap switching circuit that switches the tap of the transformer for tapping the control power supply so as to keep the voltage of the control power supply in a predetermined range, and a control of the thyristor leonard. Power supply. 2. The thyristor leonard control power supply device according to claim 1, wherein the load is a DC motor, and the control circuit is a field control circuit and a sequence control circuit of the DC motor.