SU1644298A1 - Device for ensuring continuity of power supply - Google Patents

Abstract

The invention relates to electrical engineering and can be used in power backup systems of responsible consumers powered from main and backup common-mode sources. The purpose of the invention is to improve the reliability of uninterrupted power supply. The device contains two sources of alternating common-mode voltage and contactors with a common output, the coils of which are connected to the phase terminals of the sources through the control contacts of the intermediate relays. Contactors closing contacts are connected between the phase terminals of the sources and the ends of the windings of the throttles, the middle lead of which is connected to the load terminal. The contactors of the contactors bypass the windings of the throttles. The intermediate relay control comes from two zero voltage source and control unit. The latter determines the phase shift of the source voltages and, with an unacceptable shift, after some time turns off the source, the phase of which is lagging behind.

Description

The invention relates to electrical engineering and can be used in power supply backup systems for responsible consumers powered from main and backup common-mode sources.

The aim of the invention is to improve the reliability of uninterrupted power.

FIG. 1 shows a diagram of the power part of the device; Fig. 2 is a control block diagram; on fig.Z - diagram pulse shaper.

The device contains the first 1 and second 2 sources of alternating current. Their common zero terminal 3 is designed to connect a common zero output load 4. The beginnings and ends of the windings of the choke 5 through the first closing groups of contacts 6 and 7

the first 8 and second 9 magnetic contactors, respectively, are connected to the same phase terminals 10 and 11 of each of the sources 1 and 2

Through the second disconnecting groups of contacts 12 and 13 of contactors 8 and 9, the beginning and end of the winding of the choke 5 are interconnected. The coils of contactors 8 and 9 are connected by series break contacts 14 and 15 of intermediate relays 16 and 17. The device also includes the first 18 and second 19 pulse shapers and the control unit 20. The latter consists of the first 21 and second 22 D-flip-flops, the first 23 and second 24 RS-triggers of the source disconnection, the first 25 and second 26 binary counters for determining the allowable

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phase shift, the first 27 and second 28 binary delay counters for switching on the source of the clock generator 29, as well as the first 30.1 and second 30.2 amplifiers.

Each driver 18 and 19 includes a step-down transformer 31, the primary winding of which is connected to the terminals of sources 1 or 2, and the secondary through a rectifying bridge 32, parallel to the output terminals of which a resistor 33 is connected, is connected to the Schmidt trigger 34 input, the output of which is shaper.

The device works as follows.

When a voltage appears on any of the sources i or 2, the power is supplied to the formaroraspi 18 19 n block 20 (see Fig.2).

On the first leading edge of the pulse from the former 18, the trigger 21 is set to a single position, since a single potential is constantly located at the input D, the potential at the inverse output becomes logical zero. At the same time, the ban on the operation of the counter 25 wanders, to the counting input of which impulses are received from the generator 29. Since the CRC generator frequency is known and stable, you can calculate in advance the number of pulses that should arrive; p to the counter 25 corresponding to the permissible phase shift. For example, for the industrial frequency of 50 Hz, for each determined / phase shift, each half-period is analyzed, i.e. pulse frequency of formers 18 and 19 100 Hz. In this case, the allowable voltage shift in time is selected from a rage of 1 ... 2 ms.

The signal from the slider through time, corresponding to the permissible phase shift between the voltages of sources 1 and 2, the load breaking trigger 23 is set to the zero state, at its inverse output appears the signal of the logical unit, which through its amplifier 30.1 turns on the relay 16, the last contacts opens the supply circuit of the coil of the contactor 9. Contacts 7 of this contactor 9 are open, and contacts 13 are closed. Power supply 4 will come from one source 1.

Simultaneously with switching on the source 1, the signals R from the formers 18 begin to flow to the input R of the trigger 22, which set the trigger 22 to a bullet state, a logical unit appears at its inverse output, and the unit itself resets the counter 26 to zero. The signals from the driver 18 do the same to the counting input of the counter

28 turn-on delay. The delay time is chosen equal to 2 ... 4 stress periods. The information output of the counter 28 defining this delay is connected

with the input of the trigger 24, on the inverse output of which a logical zero signal is generated. Relay 17 is not included.

When you turn on the second source 2 can be considered three cases.

0 First, the voltage phase of source 2 may be ahead of phase of source 1. In this case, trigger 21 will always be in a state where its inverse output is a logical one, since the input signal

5 R is ahead of the signal of the counting input C. After 2. ,, 4 periods of the supply voltage, the signal from the counter 27 triggers 23 to the state when its inverse output has a logic zero signal,

0 pins 14 of the relay 16 are closed, the contactor 9 is activated and the source 2 is connected via contacts 7 to the winding of the choke 5.

Second, the source voltage phase

5 2 is delayed with respect to the phase of source 1, but the delay is within acceptable limits. In this case, when the signal arrives from the driver 18, the trigger 21 is set to one state 0 and enables the counter 25 to work. But, since the phase shift is within permissible limits, the counter 25 has time to be reset until at its output, on a Vits signal of a logical unit. After

5 2 ... 4 periods from counter 27, trigger 23 is set to one state and then the process proceeds as in the first case.

Thirdly, the phase of the second wastewater is delayed with respect to the phase of the first source more than the permissible rate. This can occur when source2 is turned off. it is. But because of the engines running out at the terminals of the source 2, an emf arises, which

5 will be delayed with respect to the phase of source 1, which leads to an overvoltage on the load 4. Therefore, in the event of such a delay, the number of pulses arrives at the counter 25

0 from the clock generator 29, that by a signal from the counter 25, the trigger 23 and the counter 27 will be set to the zero state. Setting the trigger 23 to the zero position triggers through the amplifier 30.1 relay

5 16, which by its contacts 14 opens the power supply of the coil of contactor 9, which is activated and disconnects the source 2 from the choke 5.

If we consider the cases when source 2 is working, s includes source 1, then

the processes will be similar, but the chain of elements 22,24,26,28,30.2 and 17 will work.

Thus, the proposed device provides uninterrupted power in the event of the disconnection of one of the supply sources and protects the load if there are other motor loads at the terminals of these sources.

Claims (1)

Claims An uninterruptible power supply device comprising two AC sources having a common zero terminal for connecting a common zero load terminal, choke, the beginnings and ends of the windings of which are connected via the first contact groups of the first and second magnetic contactors to the corresponding phase terminals of each source, and through the second disconnecting groups of contacts of both magnetic contactors, the beginning and end of the windings of the throttles of one phase are interconnected, The lugs of the magnetic contactors are connected to the terminals of the respective sources and the middle terminal of the windings of the chokes is connected to a terminal intended for connecting the phase output of the load, characterized in that, in order to increase the reliability of the uninterrupted power supply, the first and second pulse drivers are made in the form of zero. - voltage sources with inverse output, control unit and the first and second intermediate relays, the break contacts of which are included in series with the coils of the second and first magnetic contactors, respectively, and the control unit includes two D-flip-flops, two RS-flip-off triggers source, two binary counters for determining the allowable phase shift, two binary counters for switching on the source, a clock generator and two amplifiers, the output of the first driver connected to the counting input of the first D-flip-flop and to the R input of the second D-flip-flop, and the output of the second driver is connected to the R input of the first D-flip-flop and to the counting i input of the second flip-flop, inputs D of both D-flip-flops are connected to a terminal with a potential of logical unit , the inverse outputs of the first and second D-flip-flops are connected to the inputs Reset the first and second counters for determining the allowable phase shift respectively, the counting inputs of which are connected to the generator output, and the information outputs to the inputs R of the first and second source disconnecting triggers and to the inputs. Resetting the first and second sources delay switches, respectively, the counting input of the first source switching delays are connected to the output of the second driver , and the counting input of the second delay counter on switching on the source is connected to the output of the first driver, the information output of the first and second delay counters is connected to the input S of the first and second triggers of the source disconnection, respectively, the inverse outputs of which are connected via amplifiers to the first and second intermediate relays. and