JPS59716A - Power supply switching system - Google Patents

Abstract

PURPOSE:To prevent a failure generated with a transient phenomenon, by detecting a failure of a power supply in use for interrupting it and changing over the power supply after a prescribed time, in switching the power supply from a common use to a spare or vice versa. CONSTITUTION:TR relays 4-1, 4-2 of a switch circuit 3 select any of the common use power supply 1 and the spare power supply 2 and a load 5 is given. A voltage of the common use power supply 1 is detected 6 normally and 0V at normal state is outputted and several mV at failure is outputted. A gate circuit 8 starts a timer 9 at 0V, a TR relay 10 is operated after a prescribed time, the relay contact 4-1 is closed and the common use power supply 1 is loaded 5. When the common use power supply 1 is failed and the several mV is detected 6, the gate 8 is turned off and the relay contact 4-1 is opened. Further, a gate 11 is turned on, the timer 12 is started, a TR relay 13 is operated to close the contact 4-2 and the spare power supply 2 is loaded 5. The reverse switching is done similarly while keeping a prescribed time. Thus, the failure due to the transient phenomenon of capacitive or inductive load is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a power switching system for a power supply device having a working power source and a standby power source. □ (b) Prior Art and Problems Conventionally, in a power supply device having a backup power source in addition to the current power source, switching between the current and backup power sources for the load is performed by detecting the presence or absence of the current power source. In this case, when elements such as capacitors and inductors are used in the load, an abnormal voltage is generated on the load side due to a transient phenomenon when switching from the working power supply side to the backup power supply side or from the backup power supply side to the working power supply side. Therefore, the stain source device that made the load operation unstable may be damaged or become unstable.

(C) Purpose of the Invention In view of the above-mentioned problems, an object of the present invention is to provide a new power supply switching method in which switching is performed after the abnormal voltage on the load side is eliminated when switching between the active and standby power supplies. do.

(d) Structure of the Invention According to the present invention, in a power supply system in which a working power source and a standby power source are switched as necessary by a switching circuit to supply power to a load, it is possible to prevent failures of the working power source (or standby power source). Detect and turn off the working power supply side (or standby power supply) of the switching circuit, operate a timer for a predetermined time, and connect the switching circuit to the standby power supply side (or working power supply side) with the stop signal of the timer. This is achieved by doing this.

(e) Examples of the invention Embodiments of the present invention will be described below based on the drawings.

In Figure 1, the working power source (N) 1 and the standby power source (E) 2
The outputs of the relay contacts 4-1, 4- of the switch circuit 3 are respectively
2, and when the power supplies 1 and 2 are normal, the working power supply 1 supplies power to the load 5 via the contact 4-1.

The voltage of the current power supply 1 is always compared with a reference voltage 7 by a detection circuit (hereinafter referred to as DET) 6, and when it is normal, the DET 6 outputs Ov, and when it is abnormal, it outputs a voltage mV other than Ov.

The output voltage of Ov is input to the gate circuit 8.

The gate circuit 8 turns on the gate circuit 8 with OV, and starts the first timer 9 with the output of the gate circuit 8.

Transistor relay 1 is activated by the end signal of timer 9 after a predetermined time.
0 operates, contact 4-1 is closed, and the output of power supply l is applied to the load 5V.
C supply. The nuclear load mainly consists of resistors and capacitors.

When the working power supply 1 becomes faulty, the stain pressure mV is outputted from the DET 6, and the gate circuit 8 is turned off.As a result, the transistor relay 10 stops operating and the contact 4-1 is opened, so that the current power supply 1 is connected to the load 5. Cut off the electricity that was being supplied.

On the other hand, the voltage mV turns on the gate 11, which causes the second timer 12 to operate, and after a predetermined time, the timer 12 outputs a termination signal to operate the transistor relay 13, closing the contact 4-2 and powering the standby power source 2. is supplied to the load 5.

When the working power supply 1 returns to normal, DET6j is activated as described above.
OV is output, the gate 11 is turned OFF, the transistor relay 13 is turned OFF, the contact 4-2 is opened, and the power supply to the load 5 from the standby power supply 2 is cut off, and the gate 8 is turned ON to start the first timer. 9 is activated, and after a predetermined period of time, the transistor relay 10 is operated to close the contact 4-1, and power from the working power source 2 is supplied to the load 5 again.

Now, to explain the change in voltage waveform between the prior art and the present invention, in the prior art where the contact 4-1 immediately switches to the contact 4-2, the load 5 has the waveform shown in FIG. 2 (=). Occur.

In the figure, ■ is the current power supply voltage, and ■ is the backup power supply voltage. When switching from the current voltage to the backup voltage, the waveform ■ becomes an abnormal voltage at 11 hours due to the influence of the time constant circuit on the load side. This state similarly occurs when the backup power source is switched to the active power source. This waveform (■) not only makes the operation of the load side unstable, but also damages the power supply 1 and 2 sides.

FIG. 2(b) shows a voltage waveform according to the present invention, and when the current power supply voltage ■ is cut off, the waveform reaches a zero value after Δ. The standby power source 2 is connected to the load after a time α has passed since the value becomes zero. If this condition is set to αt by βt with respect to the time constant βt of the load, the influence of the abnormal voltage (2) due to the above-mentioned transient phenomenon can be prevented when switching from the active power supply 1 to the standby power supply 2.

(B) Effects of the Invention The present invention can prevent unstable operation on the load and power supply sides due to transient phenomena on the load side that occur during power supply switching.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows a power waveform due to a transient phenomenon at the time of power switching and a waveform at the time of power switching excluding the influence of the transient phenomenon. In the figure, 1 is a working power supply, 2 is a standby power supply, 3 is a switch circuit,...! -1.4-2 is a contact for transistor relay, 5
is a load, 6 is a DET, 7 is a reference voltage, 8.11 is a gate circuit, 9 and 12 are timers, and 10°13 is a transistor relay.

Claims (1)

[Claims] Ji5 In a power supply switching system that supplies power to a load by switching between a working power source and a standby power source as necessary in a switching circuit, a fault in the working power source (or standby power source) is detected and the working power source side (or standby power source) of the switching circuit is switched. ) is turned off, a timer is operated for a predetermined period of time, and the output signal of the timer connects the switching circuit to a standby power source (or a working power source).