JPH10108362A - DC power supply - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To surely prevent deterioration of components constituting a power supply even when performing parallel operation. An output voltage of each of the DC power supplies 1 and 2 is provided in a DC power supply device for supplying an operation current to a load by connecting two DC power supplies 1 and 2 having the same specifications so as to operate in parallel. When the DC power supplies 1 and 2 are operated in parallel, the output circuit of the DC power supply whose voltage is set lower is cut off when the DC power supplies 1 and 2 are operated in parallel. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for operating a circuit board used for each device of a turbine monitoring instrument for monitoring a state of a monitored object such as a turbine generator, and particularly to a parallel operation. Also in this case, the present invention relates to a DC power supply device capable of reliably preventing deterioration of components constituting a power supply.

[0002]

2. Description of the Related Art Generally, a turbine generator generates power by rotating a turbine at high speed with steam and rotating a generator connected to the turbine. in this case,
To raise the turbine to the rated speed, first perform turning (operating while rotating the turbine at low speed to reduce the temporary bending (eccentricity) of the turbine axle), While monitoring the vibration, increase the speed to the rated speed.

On the other hand, in such vibration measurement for monitoring the vibration of the turbine generator, the vibration is monitored by a combination of a vibration detector (for example, a gap sensor) and a vibration circuit board.

That is, a vibration speed signal measured by a vibration detector is converted into a predetermined electric signal (displacement proportional signal) by a vibration circuit board, converted into an electric signal proportional to the vibration amplitude, and an alarm output is transmitted. , Which are used to make decisions to trip the turbine.

A circuit board used in such a turbine monitoring instrument needs a power supply for supplying a current for operation to the circuit board, and the current is supplied from a dedicated power supply. I have.

Further, the power supply is provided with an overcurrent protection circuit for preventing excessive current flow when an abnormality occurs in a circuit board connected to the power supply. FIG. 3 is a circuit diagram showing a configuration example of a conventional DC power supply provided with this kind of overcurrent protection circuit.

In FIG. 3, a DC power supply 11 includes a power supply transformer 11A for stepping down a voltage on the primary side to a predetermined voltage, a rectifier 11B for rectifying the stepped down voltage, a constant voltage power supply circuit 11C, and a predetermined stabilization circuit. It is composed of a constant voltage circuit 11D that generates the voltage thus generated, and an overcurrent protection circuit 11E.

The overcurrent protection circuit 11E is composed of transistors 11F and 11G, resistors 11H and 11J, and a constant voltage diode 11K. The overcurrent protection circuit 11E generates a voltage stabilized by the constant voltage diode 11K.

Now, a load is connected to the DC power supply 11,
A current is supplied from the DC power supply 11 to the load. In this case, the current at which the overcurrent protection circuit 11E operates changes the voltage V _BE between the base and the emitter of the transistor 11G by the resistance 11
When a current equal to or greater than the current value divided by the value of J flows, the transistor 11G turns on and the transistor 11F turns off.
And the output current is cut off.

When the output current is cut off, the transistor 11G turns off and the transistor 11F
Turns ON, and the current is normally supplied. As described above, the overcurrent protection circuit 11E includes the transistors 11F and 11F.
The current is limited by ON / OFF control of G.

However, in the above-described DC power supply, when two DC power supplies 11 having the same specifications are connected in parallel and the parallel operation is performed, the voltage is applied to the anode of the voltage matching diode 11M. Therefore, there is a problem that components constituting the power supply deteriorate quickly.

[0012]

As described above, in the conventional DC power supply, when two DC power supplies having the same specifications are connected in parallel and the parallel operation is performed, deterioration of the components constituting the power supply and the like occur. There was a problem that was faster. An object of the present invention is to provide a DC power supply device capable of reliably preventing components constituting a power supply from deteriorating even when performing parallel operation.

[0013]

According to the present invention, in order to achieve the above object, two DC power supplies of the same specifications are connected in parallel operation to supply an operating current to a load. In the power supply device, the voltages are set so that the output voltages of the respective DC power supplies have a constant voltage difference from each other, and when the respective DC power supplies are operated in parallel, the DC power supply having the lower voltage is set. The output circuit is shut off.

Therefore, in the DC power supply of the present invention, the output voltages of the two DC power supplies connected in parallel operation are set to have a constant voltage difference from each other, and each DC power supply is When performing parallel operation of
By shutting off the output circuit of the DC power supply whose voltage is set lower, the voltage is not supplied to the output circuit of the DC power supply whose voltage is set lower even during parallel operation. And the like can be reliably prevented, and a highly reliable DC power supply device can be obtained.

[0015]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing the DC power supply device according to the present embodiment. In FIG. 1, a DC power supply 1 includes a power transformer 1A for stepping down a voltage on a primary side to a predetermined voltage, a rectifier 1B for rectifying the stepped down voltage, and a constant voltage circuit 1 for generating a predetermined stabilized voltage.
C and an overcurrent protection circuit 1D.

The overcurrent protection circuit 1D includes transistors 1E, 1F, 1G, a resistor 1J, an FET switch 1K,
The differential amplifier 1L, the comparator 1M, and the NAND gates 1N, 1P, 1Q are configured as shown.

In FIG. 1, 1U denotes an overvoltage protection circuit,
H indicates a diode, 1R indicates a resistor, and R indicates a resistor. Now, a load (not shown) is connected to the DC power supply 1, and a current is supplied from the DC power supply 1 to the load.

In this case, the transistor 1G is turned on when a current equal to or greater than the current obtained by dividing the base-emitter voltage V _BE of the transistor 1G by the value of the resistor 1J flows when the overcurrent protection circuit 1D operates. , Transistor 1E, 1
F is turned off, and the output current is cut off.

When the output current is cut off, the transistor 1G is turned off, and the transistors 1E and 1E are turned off.
F turns ON, and current is supplied normally. At this time, the voltage between both ends of the resistor 1R is amplified by the differential amplifier 1L. When the output voltage of the differential amplifier 1L becomes higher than the inverting terminal input voltage (Vref) of the comparator 1M, the output of the NAND gate 1N becomes the level. 0, the output of the NAND gate 1P becomes level 1, the FET switch 1K turns on,
The transistors 1E and 1F are turned off, and the output current is cut off.

On the other hand, this overcurrent protection circuit 1D
D gates 1P and 1Q constitute a self-holding circuit. That is, when an overcurrent is detected, after the output current is cut off, the output circuit is not operated until the input power is once turned off and then turned on again.

As a result, since the power is not restored unless the power supply voltage is turned on once, the transistors 1E and 1F are turned on.
/ OFF is not repeated. This can prevent the transistors 1E and 1F of the overcurrent protection circuit 1D from deteriorating.

On the other hand, such a DC power supply having the same specification
When two units are connected and the parallel operation is performed, the output terminals of the respective DC power supplies are used in abutting relation. At this time, the output voltage is given a voltage difference, the diode of the DC power supply whose voltage is set lower is turned off, and the current is supplied from the DC power supply whose voltage is higher.

That is, the output voltage of each DC power supply is
The voltage is set so as to have a constant voltage difference from each other, and when the respective DC power supplies are operated in parallel, the output circuit of the DC power supply whose voltage is set lower is cut off.

In this state, the voltage across the resistor 1V of the DC power supply whose voltage is set lower becomes higher than the reference voltage 1W, so that the output voltage of the comparator 1X saturates to the minus power supply voltage. Is lower than the emitter voltage, the transistor 1E is also turned off, and the output voltage is cut off.

When the transistor 1E is turned off, no voltage is applied to each component after the transistor 1E. Thus, even when two DC power supplies are operated in parallel, it is possible to reliably prevent deterioration of components constituting the power supplies.

FIG. 2 is a circuit diagram showing a configuration example of a DC power supply device when two such DC power supplies having the same specifications are connected so as to be able to operate in parallel. Here, as a specific example of the parallel connection, the output voltage is set to +15 VDC and +1
A DC power supply set to 4.8 V will be described.

In FIG. 2, the DC power supply 1 is set so that the output voltage becomes +15 VDC. At this time, the voltage between both ends of the resistor 1V is set to 5V. On the other hand, DC power supply 2 is set so that the output voltage is +14.8 VDC. At this time, the voltage across the resistor 2V is 5
V is set in advance.

When the DC power supplies 1 and 2 are connected in parallel to each other, the DC power supply 2 having an output voltage set to +14.8 V
Is turned off, and the output voltage of the DC power supply becomes the output voltage of the DC power supply 1 having the higher voltage, and this output voltage is supplied to the load 3.

In this state, the voltage across the resistor 2V of the DC power supply 2 becomes higher than the reference voltage element 2W, and the comparator 2X operates to saturate the output voltage to the negative power supply voltage. When the output voltage of the comparator 2X saturates to the minus power supply voltage, the transistor 2X
Since the base potential of F becomes lower than the emitter potential, the transistors 2F and 2E are turned off, and the output voltage is cut off.

Since the transistor 2E is turned off, no voltage is applied to each component after the transistor 2E. Thereby, even when the two DC power supplies 1 and 2 are operated in parallel, it is possible to reliably prevent the components constituting the power supply from deteriorating.

As described above, in the DC power supply of the present embodiment, when an overcurrent is detected, the output circuit is operated until the input power is once turned off after the output current is turned off and then turned on again. Since it is not performed, it is possible to reliably prevent the components of the overcurrent protection circuit 1D from deteriorating.

When the two DC power supplies 1 and 2 are operated in parallel, the voltages are set so that the output voltages of the DC power supplies 1 and 2 have a constant voltage difference from each other. When the DC power supplies 1 and 2 are operated in parallel,
Since the output circuit of the DC power supply whose voltage is set lower, that is, the DC power supply that does not supply current is cut off (OFF), the power supply can be used even when the two DC power supplies 1 and 2 are operated in parallel. Can reliably be prevented from deteriorating the components constituting the device.

As described above, a highly reliable DC power supply can be obtained. The present invention is not limited to the above embodiment, but can be implemented in the same manner as described below.

In the above embodiment, a case has been described in which the present invention is applied to a DC power supply for supplying a current for operation to a circuit board used in a turbine monitoring instrument. However, the present invention is not limited to this, and various other devices are used. DC power supply that supplies operating current to the circuit board
The invention is equally applicable.

[0035]

As described above, according to the present invention, in a DC power supply device for connecting two DC power supplies of the same specification so as to be able to operate in parallel and supplying an operation current to a load, The voltage is set so that the output voltage of the DC power supply has a certain voltage difference with each other, and when the respective DC power supplies are operated in parallel, the output circuit of the DC power supply whose voltage is set lower is shut off. With this configuration, it is possible to provide a DC power supply device that can surely prevent deterioration of components constituting the power supply even when performing parallel operation.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a DC power supply device according to the present invention.

FIG. 2 is a circuit diagram showing a configuration example of a DC power supply device when two DC power supplies of the same specification are connected so as to be able to operate in parallel.

FIG. 3 is a circuit diagram showing a configuration example of a conventional DC power supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1: DC power supply, 1A: Power transformer, 1B: Rectifier, 1C: Constant voltage circuit, 1D: Overcurrent protection circuit, 1E, 1F, 1G: Transistor, 1K: FET switch, 1L: Differential amplifier, 1M: Comparator, 1N, 1P, 1Q: NAND gate, 1U: overvoltage protection circuit, 1H: diode, 1R: resistor, R: resistor, 1V: resistor, 1W: reference voltage element, 1X: comparator, 2H: diode, 2V: resistor, 2W ... Reference voltage element, 2X ... Comparator, 2E, 2F ... Transistor.

Claims (1)

[Claims] 1. A DC power supply device for connecting two DC power supplies of the same specification so as to be able to operate in parallel and supplying a current for operation to a load, wherein the output voltage of each of the DC power supplies is fixed to each other. The voltage is set so as to have a voltage difference, and when the respective DC power supplies are operated in parallel, the output circuit of the DC power supply whose voltage is set lower is cut off. DC power supply.