JPH0393435A - Operation testing circuit for uninterruptible power source switching apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an uninterruptible switch that can test the operation of an AC switch used in a device that uninterruptively switches the power source of AC power supplied to a load during operation. Concerning the operation test circuit for power supply switching equipment. [Prior Art] For loads such as computers that need to avoid short-term power outages as well as fluctuations in voltage and frequency as much as possible, power is constantly supplied from the first AC power source, and The second backup AC power supply is operated without load in synchronization with the first AC power supply, and if an abnormality occurs in the first AC power supply, the system switches to the second AC power supply without interruption. FIG. 3 is a circuit diagram showing a conventional example of an uninterruptible power supply switching device, in which AC power of constant voltage and constant frequency is supplied to the computer 2 as a load from an inverter 11 as a first AC power source. Power is supplied via the first AC switch 12 and the first circuit breaker 13. The backup power source 2l as the second AC power source is generally a commercial power source, but the open circuit breaker 6 and the second circuit breaker 23 are always closed, and only the second AC switch 22 is turned off. put. At this time, the synchronization detector 3 inputs the output voltage of the inverter 1l and the output voltage of the backup power supply 2l, and if both power supplies are in a synchronized state, a logic H signal is sent to the AND element 1.
6 and 26. Here, the power supply source for computer 2 is connected to inverter l1.
When you want to switch from the backup power source 21 to the backup power source 21, press the backup power source selection switch 24 to change the input signal to the AND element 26 from the logic L signal to the logic H signal.
As mentioned above, since the synchronization detector 3 is outputting a logic H signal, the output of the AND element 26 changes to a logic H signal. Therefore, the output from the flip-flop 4 to the AND element 17 becomes a logic L signal. Also, the output to the AND element 27 is switched to a logic H signal. Since the oscillator 5 constantly oscillates a pulse signal, the gate drive circuit 18, which had previously received the signal from the AND element 17 and sent out the ON signal to the first AC switch 12, now changes to the backup power selection switch 24. By pressing , the transmission of this ON signal is stopped, and conversely, the gate drive circuit 28 starts transmitting an ON signal, so that the second AC switch 22 is turned on. That is, the supply of AC power to the computer 2 is switched from the inverter 1l to the backup power supply AL21 without interruption. In order to switch the power supply from the backup power source 21 to the power transmission from the inverter 11 again, the inverter selection switch 14 is pressed, and the switching is performed without interruption, in the reverse operation to that described above. FIG. 4 is a time chart showing the operation of each part of the conventional circuit shown in FIG. (C) is a change in the output signal C of the synchronous detector 3, (2) is a change in one output signal D of the flip-flop 4, (E) is the other output signal of the flip-flop 4. (f) is the change in the output signal of the oscillator 5, (g) is the change in the output signal G of the gate drive circuit l8, (h) is the change in the output signal J of the gate drive circuit 28, and (ri) is the change in the output signal J of the gate drive circuit 28. Operation of the first AC switch 12,
(J) represents the operation of the second AC switch 22, respectively. As shown in FIG. 4, T. By pressing the backup power supply selection switch 24 at this point, it can be seen that the power supply has been switched immediately. [Problems to be Solved by the Invention] By the way, in the uninterruptible power supply switching device using the conventional circuit shown in FIG. 3, it is not possible to check the operation of the AC switch 12 or 22 while the device is in operation. Therefore, for example, when an operation is performed to switch the AC power supplied by the inverter l1 to the backup power supply 2l, if the second AC switch 22 is malfunctioning, the switching cannot be performed.
This would interrupt the power supply to the computer 2, but there was an inconvenience in that it was impossible to determine whether the AC switch 12 or 22 was normal or not unless the switching operation was performed. Therefore, an object of the present invention is to enable tests to be performed to confirm that the AC switch operates normally and that uninterruptible switching can be performed reliably even when the uninterruptible power supply is in use. [Means for Solving the Problems] In order to achieve the above-mentioned object, the operation test circuit of the present invention connects a first AC switch and a first circuit breaker composed of semiconductor switching elements from a first AC power source. a circuit that supplies AC power to the load via a second AC power source, a circuit that supplies AC power to the load from a second AC power source via a second AC switch constituted by a semiconductor switch element, and a second circuit breaker; a synchronization detection means for detecting a synchronized state of an AC power supply and a second AC power supply; a power supply switching command means; and a power supply switching command means for mutually turning on and off the first AC switch and the second AC switch an uninterruptible power supply switching device for switching AC power supplied to the load without interruption, comprising: means for applying an on signal to the first AC switch when the first circuit breaker is opened; It shall be provided with means for displaying that the switch is turned on, means for giving an on signal to the second AC switch when the second circuit breaker is opened, and means for displaying that the second AC switch is turned on. ．． [Function] A circuit breaker is installed between the AC switch for uninterruptible switching and the load to protect the AC switch from overcurrent generated on the load side, but this circuit breaker is normally closed. It has been done. Therefore, by opening this circuit breaker belonging to a power supply that is not supplying power, the AC switch belonging to this power supply is automatically turned on, and the voltage on the output side of this AC switch is detected. This is to make it possible to confirm that the AC switch is turned on, and to prevent uninterruptible power supply switching from failing due to a defect in the AC switch. [Embodiment] Figure 1 is a circuit diagram showing an embodiment of the present invention. The loads shown in FIG. 1 include a computer converter 2, a synchronous detector 3, a flip-flop 4, an oscillator 5, an inverter l1 as a first AC power supply, a first AC switch 12, a first circuit breaker l3, and an inverter. Selection switch l4, AND element 16. 1? ．． 26. 27, gate drive circuit 18
．． 28. Backup power supply 2l as a second AC power supply
, the second AC switch 22, the second circuit breaker 23, and the backup power supply selection switch 24 have already been described in the conventional circuit shown in FIG. 3, so their explanations will be omitted. Note that the direct feed circuit breaker 7 closes the first AC switch 12 and the second AC switch 22 in the case of a failure, and connects the open circuit breaker 6 to rIIi, thereby shutting down the AC from the backup power supply 21. This is to enable power to be directly transmitted to the computer 2, which is a load. In the present invention, the output signal K of the auxiliary contact 13B of the first circuit breaker l3 is sent to the logical sum element 33 via the inverter 32,
It is applied together with one output signal D of the flip-flop 4, and the output of this OR element 33 is applied to the aforementioned AND element 17 and also to the first relay 34. Similarly, the output signal N of the auxiliary contact 23B of the second circuit breaker 23 is passed through the inverting element 42 to the OR element 43, and the flip-flop 4
The output of the OR element 43 is applied to the AND element 27 described above, and is also applied to the second relay 44.

Furthermore, a series circuit of the contact 34A of the first relay 34 and the display 35 is connected between the lines on the output side of the first AC switch l2, and a second relay is also connected between the lines on the output side of the second AC switch 22. A series circuit of contact 44A of 44 and display 45 is connected. For example, the AC power output by the inverter 11 is
When supplying to the computer 2 via the AC switch 12 and the first circuit breaker 13, the open circuit breaker 6 and the second circuit breaker 2
3 is closed, and only the second AC switch 22 is off, so that AC power from the backup power supply 21 can be supplied to the computer 2 at any time by turning on the second AC switch 22. ing. (At this time, the direct feed circuit breaker 7 is of course open.) In this state, in order to test that the second AC switch 22 operates reliably, the second circuit breaker 23 is opened. The second circuit breaker contact 23B, which had been in the open state until then and was giving a logic H signal to the inverting element 42,
The circuit becomes closed according to the opening of the circuit. As a result, a logic H signal is sent from the inverting element 42 to the OR element 43, and even if the other output signal E of the preamp-flop 4 is a logic L signal, the logic output from the OR element 43 is The H signal causes the gate drive circuit 28 to pass through the AND element 27.
sends an on signal to the second AC switch 22 from
The AC switch 22 is turned on. However, the second circuit breaker 23
Since the circuit is open, there is no risk that the backup power supply 2l will operate in parallel with the inverter l1. Further, the logic H signal output from the OR element 43 excites the second relay 44, so the second relay contact 44A is closed. At this time,
As described above, the second AC switch 22 is on and outputs the voltage of the backup power supply 2l to its output side, so this voltage is transmitted to the display 45 via the second relay contact 44A.
to indicate that the second relay 22 has operated normally. If this indicator 45 does not operate, it can be known that there is an abnormality in the second AC switch 22.
In this way, if the second circuit breaker 23 is closed after confirming the operation of the second AC switch 22, the second AC switch 22 will be turned off, and when the backup power selection switch 24 is pressed and a power supply switching command is issued, the second AC switch 22 will be turned off. You will be prepared. If the computer 2 is operating on AC power from the backup power supply 2l, open the first circuit breaker 13 to test whether the first AC switch l2 operates normally by the same operation as described above. Can be done. In addition, 15. 25. 32. 42 are resistors, which send out a logic H signal or a logic L signal to the next stage in response to opening or closing of a contact provided between this resistor and the M potential. FIG. 2 is a time chart showing the operation of each part of the embodiment circuit shown in FIG. (C) is a change in the output signal C of the synchronous detector 3, (2) is a change in one output signal D of the flip-flop 4, (E) is the output of the other output signal of the flip-flop 4. Changes in the signal E, (f) changes in the output signal F of the oscillator 5, (g) changes in the output signal G of the gate drive circuit 18, (h) changes in the output signal J of the gate drive circuit 28, (ri) is a change in the input signal K of the inverting element 32, (nu) is a change in the input signal N of the inverting element 42, (ru)
indicates the operation of the first AC switch 12, (O) indicates the operation of the second AC switch 22, (W) indicates the operation of the first circuit breaker 13, and (force) indicates the operation of the second circuit breaker 23. There is. As shown in FIG. 2, if the second circuit breaker 23 is opened at time T2 while AC power is being supplied to the computer 2 from the inverter l1 via the first AC switch 12 and the first circuit breaker 13, the second AC Since it can be confirmed that the switch 22 is turned on, the second circuit breaker 23 is closed at time T. Next, by pressing the backup power supply selection switch 24 at time T4, the first AC switch 12 is turned off, the second AC switch 22 is turned on, and the power to the computer 2 is switched to the power supply from the backup power supply 21. [Effects of the Invention] Conventionally, it has not been possible to test whether or not the AC switch for switching the power supply operates normally while the uninterruptible power supply switching device is in use. However, according to the present invention, the AC switch By adding a simple logic circuit, it is possible to automatically turn on the AC switch and display that it has been turned on when the circuit breaker between the AC switch and the load is opened. Since it is possible to avoid problems where the power supply to the load is interrupted when switching the power supply due to a malfunction of the switch, the reliability of the uninterruptible power supply switching device can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a time chart showing the operation of each part of the embodiment circuit shown in Fig. 1, and Fig. 3 is a conventional example of uninterruptible power supply switching and reinstallation. FIG. 4 is a time chart showing the operation of each part of the conventional circuit shown in FIG. 2... Computer as load, 3... Synchronous detector, 4... Flip-flop, 5... Oscillator, 6...
... Open circuit breaker, 7 ... Direct feed circuit breaker, l1 ... 1st
Inverter as an AC power source, 12... first AC switch, 13... first breaker, 13B... first breaker contact, 14... inverter selection switch, 15. 2
5, 31. 41...Resistance, 16.1? , 26.
27... logical product element, 18. 28... Gate drive circuit, 21... Bank amplifier power supply as second AC power supply, 22... Second AC switch, 23... Second breaker, 23B... Second breaker contact, 24... Backup power 'a selection switch, 32. 42...inversion element, 33. 43... OR element, 34... First relay, 34A... First relay contact, 35. 45...
・Indicator, 44...Second relay, 44A...Second relay connection 3 Figure

Claims (1)

[Claims] 1) A circuit that supplies AC power from a first AC power source to a load via a first AC switch and a first circuit breaker configured with a semiconductor switching element, and a second AC power source configured with a semiconductor switching element from a second AC power source. A circuit for supplying AC power to the load via an AC switch and a second circuit breaker, synchronization detection means for detecting a synchronized state of the first AC power supply and the second AC power supply, power supply switching command means; An uninterruptible power supply switching device for switching AC power supplied to the load without interruption, comprising means for mutually switching on and off of the first AC switch and the second AC switch based on a power supply switching command, means for giving an on signal to the first AC switch when the first circuit breaker is opened; means for displaying that the first AC switch is turned on; and an on signal to the second AC switch when the second circuit breaker is opened. 1. An operation test circuit for an uninterruptible power supply switching device, characterized in that the circuit comprises: means for giving the second AC switch; and means for displaying that the second AC switch is turned on.