JPH10164772A - Power supply switching circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply switching circuit with a detecting means for detecting a short circuit failure or an open circuit failure in a semiconductor relay, in which a semiconductor switching element is used for fear that a contact of a power switching relay is melted by an inrush current. SOLUTION: A power supply switching circuit includes a first thyristor circuit 11 made up of thyristors SCR1 to SCR4 for controlling an AC power feeding line between a first power supply (ordinary power supply) and a load and turned on and off under control according to the on/off state of the first power supply, and a second thyristor circuit 12 made up of thyristors SCR5 to SCR8 for controlling an AC power feeding line between a second power supply (auxiliary power supply) and the load and turned on and off under control according to the on/off state of the second power supply. In this way, an electronic power supply switching circuit is constituted by these thyristors with an allowable current larger than that of mechanical relays, and thereby an allowable range for an inrush current at switching time of the power supply can be enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply switching circuit, and more particularly, to a power supply switching circuit for switching between a normal power supply and a standby power supply for a load.

[0002]

2. Description of the Related Art As a conventional power supply switching circuit, for example,
There is one shown in FIG. Power supply switching circuit 1 shown in FIG.
Uses a mechanical power supply switching relay 2 that switches and connects each output of a normal power supply B1 and a backup power supply B2 to a load 3. The power supply switching relay 2 includes a normal power supply B1
Circuit 2a which is excited by the power supply voltage output from
Operating contacts R1 and R2 that close when the excitation circuit 2a is excited, and recovery contacts R3 and R4 that open when the excitation circuit 2a is excited.

Accordingly, in the power supply switching circuit 1 of FIG. 5, when the excitation circuit 2a of the power supply switching relay 2 is excited by the power supply voltage output from the ordinary power supply B1, the operating contacts R2 and R2 are closed. Output of the regular power supply B1 to load 3
To supply the load 3 with the power supply voltage output from the ordinary power supply B1, and disconnect the output of the standby power supply B2 from the load 3 by opening the recovery contacts R3 and R4.

In the power supply switching circuit 1 shown in FIG. 5, when the power supply voltage output from the normal power supply B1 is stopped due to a power failure or the like, the excitation circuit 2a in the power supply switching relay 2 is de-energized, and the operation is started. Open the contacts R1 and R2 to open the normal power supply B1
Output from the load 3 and the recovery contact R3
R4 is closed and the output of the standby power supply B2 is connected to the load 3;
The power supply voltage output from the standby power supply B2 is supplied to the load 3.

[0005] Incidentally, S1 to S12 in the figure indicate connection terminals, respectively.

[0006]

However, the power supply and the load in which such a conventional power supply switching circuit 1 of FIG. 5 is used tend to increase the load capacity in recent years and are also loads. In many cases, an insulating transformer is added to the output terminal of a power supply to protect an electronic circuit or the like, so that an inrush current at the time of power supply switching by the power supply switching circuit 1 increases, and a mechanical power supply switching relay 2 There was a problem that the contacts inside were welded.

For example, as shown in FIG. 6 which shows an example of the inrush current, the current value of the inrush current at the time of power supply switching may reach "500 A". There is a problem that the contacts in 2 are welded.

This occurs because the rush current exceeds the limit current value at which the metal contacts are welded because the contacts in the mechanical power supply switching relay 2 are metal contacts.

The power supply switching circuit 1 utilizing the mechanical power supply switching relay 2 shown in FIG. 5 is widely used in practice, and measures are taken to prevent the contacts from being welded by the rush current at the time of power supply switching. Is required.

Therefore, as a power supply switching circuit using a switching element capable of withstanding an inrush current as shown in FIG. 6, for example, a semiconductor relay (solid state relay: SSR) having a larger allowable current than a mechanical relay A power supply switching circuit utilizing the above is conceivable. However, in the case of this power supply switching circuit, if a rush current exceeding the allowable current of the semiconductor relay flows, even the semiconductor relay may be short-circuited or opened, and the power supply switching operation may not be performed. When a short-circuit fault or an open fault occurs in a relay, it is necessary to detect the short-circuit fault or the open fault and take a countermeasure.

An object of the present invention is to use a semiconductor relay as a switching element so as to prevent welding of a contact of a power supply switching relay due to an inrush current at the time of power supply switching, and to take measures for detecting a short-circuit fault or an open fault in the semiconductor relay. To provide a power supply switching circuit.

[0012]

According to the first aspect of the present invention,
A first switching element for controlling the opening / closing of a power supply voltage supply line between the service power supply and the load in accordance with the presence or absence of the service power supply, and a power supply voltage supply line between the backup power supply and the load with or without the protection power supply A second switching element that performs closing / opening control in accordance with the following, a first short-circuit detection circuit that detects a short-circuit failure of the first switching element, and a second circuit that detects a short-circuit failure of the second switching element. A short-circuit detection circuit, an open-circuit detection circuit for detecting an open-circuit failure of the first switching element, and a short-circuit detection circuit connected between the service power supply and the first switching element. First closing / opening means for closing / opening a power supply voltage supply line between the normal power supply and the first switching element in accordance with the operation and the open detection operation by the open detection circuit; A power supply voltage supply line connected between the standby power supply and the second switching element, and connected to the standby power supply and the second switching element in response to a short-circuit detection operation by the second short-circuit detection circuit; Closing /
Second closing / opening means for opening; an exciting circuit for exciting / non-exciting by a combined voltage of a power supply voltage supplied from the normal power supply and a power supply voltage supplied from the standby power supply;
An anti-phase detection relay having a contact that is closed / opened by the excitation circuit; an operation of the anti-phase detection relay determines whether a wiring connected to the normal power supply or a wiring connected to the standby power supply has a reverse phase; Phase detection circuit for detecting whether
It is characterized by having.

According to the power supply switching circuit of the first aspect of the present invention, the power supply voltage supply line between the service power supply and the load is closed / opened by the first switching element in accordance with the presence or absence of the service power supply. The power supply voltage supply line between the standby power supply and the load is closed / opened by the second switching element in accordance with the presence or absence of the standby power supply, and the first short-circuit detection circuit detects a short-circuit failure of the first switching element. Is detected, or when an open failure of the first switching element is detected by an open detection circuit, a first closing / opening connected between the normal power supply and the first switching element. The means closes / opens the power supply voltage supply line between the service power supply and the first switching element, and the second short-circuit detection circuit causes a short-circuit failure of the second switching element. When detected, a power supply voltage supply line between the auxiliary power supply and the second switching element is provided by a second closing / opening means connected between the auxiliary power supply and the second switching element. Is closed / opened. Also, an excitation circuit which is excited / de-energized by a composite voltage of a power supply voltage supplied from the normal power supply and a power supply voltage supplied from the standby power supply, and a reverse having a contact closed / opened by the excitation circuit. By a reverse phase detection circuit having a reverse phase detection relay having a phase detection relay, it is determined whether or not the wiring connected to the normal power supply or the wiring connected to the standby power supply is in reverse phase by the operation of the reverse phase detection relay. Is detected.

Therefore, an electronic power supply switching circuit using a switching element (for example, a thyristor or the like as a semiconductor relay) having a larger allowable current than that of a conventional mechanical relay is used. Can be expanded.

Further, a first short-circuit detecting circuit for detecting a short circuit of the first switching element, an open detecting circuit for detecting opening of the first switching element, and short-circuit detecting and opening by the first short-circuit detecting circuit A first closing / opening means for closing / opening a power supply line from the commercial power supply to the first switching element based on the opening detection by the detection circuit, whereby short-circuit failure and opening of the first switching element are provided. The failure can be reliably detected, and the switching operation between the normal power supply and the standby power supply can be reliably performed.

Further, a second short circuit detecting circuit for detecting a short circuit of the second switching element, and a power supply line from the standby power supply to the second switching element is closed by detecting the short circuit by the second short circuit detecting circuit. And a second closing / opening means for opening / closing the second switching element to reliably detect a short-circuit failure of the second switching element and to reliably perform a switching operation between the normal power supply and the standby power supply. it can.

Further, an excitation circuit which is excited / de-energized by a composite voltage of a power supply voltage supplied from the normal power supply and a power supply voltage supplied from the standby power supply, and a contact which is closed / opened by the excitation circuit A reverse phase detection relay including a reverse phase detection relay having a reverse phase detection relay, wherein the operation of the reverse phase detection relay detects whether the wiring connected to the normal power supply or the wiring connected to the standby power supply is in reverse phase. By providing the phase detection circuit, the opposite phase connection of the power supply wiring is reliably detected and notified, so that the operator can deal with it.

As a result, the power supply switching circuit can secure operational stability by employing the switching element, and can improve the reliability by providing a circuit for coping with the failure of the switching element. In addition, the provision of the anti-phase detection circuit allows the power supply switching circuit to have an anti-phase detection function of the power supply wiring between the external normal power supply and the standby power supply and the power supply switching circuit, thereby improving the function of the power supply switching circuit. Can be achieved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 4 show an embodiment of a power supply switching circuit for switching power supplied to a traffic light or the like to which a power supply switching circuit of the present invention is applied.

First, the configuration will be described.

FIG. 1 shows a power supply switching circuit 10 according to this embodiment.
FIG. 3 is a diagram showing a circuit configuration of FIG. In FIG. 1, a power supply switching circuit 10 includes a first thyristor circuit 11, a second thyristor circuit 12, a first rectifier circuit 13, a second rectifier circuit 14, a DC voltage generation circuit 15, a first short circuit. Detection circuit 1
6. Second short-circuit detecting circuit 17, open-circuit detecting circuit 18, reverse-phase detecting circuit 19, relays R11, R12, R2, short-circuit detecting relays FR1, FR2, open-circuit detecting relay RL, no-fuse breakers NFB1, NFB2, and LEDs L1 to L1.
It is composed of EDL3.

After the power switch S1 is turned on, the power transformer T1 reduces the AC voltage (for example, AC 6600V) supplied from the No. 1 power source (for example, AC 6600V) to a desired AC voltage (for example, AC 100V), and the first thyristor. Circuit 1
1. It is supplied to the first rectifier 13 and the DC voltage generator 15. The first thyristor circuit 11 includes a thyristor SC
Each of the thyristors SCR1 to SCR4 is turned on by a gate voltage supplied from the first rectifier circuit 13, and an AC voltage supplied from the secondary side of the power transformer T1. To the load.

After the power switch S2 is turned on, the power transformer T2 reduces the AC voltage (for example, AC 6600V) supplied from the No. 2 power source (backup power source) to a desired AC voltage (for example, AC 100V), and the second thyristor Circuit 1
2. It is supplied to the second rectifier circuit 14 and the DC voltage generation circuit 15. The second thyristor circuit 12 includes a thyristor SC
Each of the thyristors SCR5 to SCR8 is turned on by the gate voltage supplied from the second rectifier circuit 14, and the AC voltage supplied from the secondary side of the power transformer T2 is constituted by R5 to SCR8 (second switching element). To the load.

The first rectifier circuit 13 is composed of a transformer and a full-wave rectifier, rectifies the AC voltage supplied from the power transformer T1, and supplies the rectified voltage to each of the thyristors SCR1 to SCR4 in the first thyristor circuit 11. A gate voltage is generated, and an excitation voltage for exciting the relays R11 and R12 is generated. The relay R11 is connected to the first rectifier circuit 13
When the exciting circuit is excited by the exciting voltage supplied from the rectifying circuit 13, the operating contacts R111a to R113a and the restoring contact R111b are closed / opened, and the thyristors SCR1 to SCR1 are controlled. A supply line for supplying a gate voltage to the SCR 4, a supply line for supplying a gate voltage from the second rectifier circuit 14 to the thyristors SCR 5 to SCR 8, and 24 V DC from the DC voltage generation circuit 15 to the no-fuse breakers NFB 1 and NFB 2. ON / OFF control of each supply line is performed.

When the exciting circuit is excited by the exciting voltage supplied from the first rectifier circuit 13, the relay R12 performs a slow motion / slow alarm operation to close / open the operating contacts R121a to R122a and the recovery contact R121b. Control the first rectifier circuit 13
From the second rectifier circuit 14 to the thyristors SCR5 to SCR8, and from the DC voltage generation circuit 15 to the no-fuse breakers NFB1 and NFB2 to supply 24V DC to the thyristors SCR1 to SCR4. Are turned on / off.

The second rectifier circuit 14 includes a transformer and a full-wave rectifier, rectifies the AC voltage supplied from the power transformer T2, and supplies the rectified voltage to each of the thyristors SCR5 to SCR8 in the second thyristor circuit 12. A gate voltage is generated, and an excitation voltage for exciting the relay R2 is generated. When the exciting circuit is excited by the exciting voltage supplied from the second rectifier circuit 14, the relay R2 performs fast / fast releasing operation to control the closing / opening of the operating contact R21a. D for no fuse breaker NFB1
ON / OFF control of the supply line to which C24V is supplied.

The DC voltage generating circuit 15 is composed of full-wave rectifiers connected in parallel. The DC voltage generating circuit 15 rectifies AC voltages supplied from the power transformers T1 and T2 to generate 24 V DC, And the no-fuse breakers NFB1 and NFB2. The first short-circuit detection circuit 16 detects a short-circuit state of each of the thyristors SCR1 to SCR4 in the first thyristor circuit 11 based on a current flowing through the short-circuit detection transformer CT, and performs detection / non-detection of the short-circuit state. Accordingly, the short-circuit detection relay FR1 is energized / de-energized. When the first short-circuit detection circuit 16 is energized / de-energized, the short-circuit detection relay FR1 operates.
11a is closed / opened, and the supply line to which 24V DC is supplied from the DC voltage generation circuit 15 to the no-fuse breaker NFB1 is ON / OFF controlled.

The second short-circuit detection circuit 17 detects a short-circuit state of each of the thyristors SCR5 to SCR8 in the second thyristor circuit 12 based on a voltage generated in the short-circuit detection transformer PT, and detects the short-circuit state. / Short-circuit detection relay FR2 is excited / non-excited in response to the non-detection. Short detection relay F
When the second short-circuit detecting circuit 17 is energized / de-energized, the R2 closes / opens the operation contact FR21a and turns on the supply line from the DC voltage generation circuit 15 to which the 24V DC is supplied to the no-fuse breaker NFB2. / OFF control.

The open detecting circuit 18 comprises a transformer T3 and a full-wave rectifier. The open detecting circuit 18 detects an open state of each of the thyristors SCR1 to SCR4 in the first thyristor circuit 11 by a power supply voltage supplied to a load, and detects the open state. The energization / non-excitation of the open detection relay RL is performed in response to the detection / non-detection.
The release detection relay RL is excited /
When de-energized, the recovery contact RL1b is closed / opened,
No-fuse breaker NF from DC voltage generation circuit 15
Turn ON / OF the supply line to which DC24V is supplied to B1
Perform F control.

The anti-phase detecting circuit 19 includes the DC voltage generating circuit 1
5, the power supply wiring connected from the No. 1 power supply to the primary side of the power supply transformer T1 and the power supply wiring connected from the No. 2 power supply to the temporary side of the power supply transformer T2 are in-phase based on 24 V DC supplied from each full-wave rectifier. This is a circuit for detecting whether the phase is reversed or not. If the power supply wirings are connected in the same phase and AC voltage is supplied from both the No. 1 power supply and the No. 2 power supply, an AC voltage having a peak value twice as high is supplied to the DC voltage generation circuit 15 as shown in FIG. When the power supply lines are connected in the same phase and an AC voltage is supplied from one of the first power supply and the second power supply, the AC voltage for one power supply is applied. Also, 1
When the power supply wiring from the power supply No. 2 and the power supply wiring from the power supply No. 2 are out of phase with each other and the AC voltage is supplied from both the power supply No. 1 and the power supply No. 2 as shown in FIG. The AC voltages are applied to the DC voltage generating circuit 15 so as to cancel each other. Therefore, in the case of the in-phase shown in FIG.
The reverse-phase detection relay RP is excited by 24V DC supplied from the DC power supply, and its recovery contacts RP1b and RP2b are opened.
In the case of the reverse phase shown in (1), the DC 24 V supplied from the DC voltage generation circuit 15 is lost, the reverse phase detection relay RP is de-energized, and the recovery contacts RP1b and RP2b are closed to detect the reverse phase. Then, an external negative-phase detection lamp or the like is turned on to notify that the power supply wiring is connected in reverse phase.

The ON / OF of the switch SW1 connected between the DC voltage generation circuit 15 and the reverse phase detection circuit 19
By the F operation, it is possible to arbitrarily select whether to enable or disable the reverse phase detection function by the reverse phase detection circuit 19.

The no-fuse breaker NFB1 (first closing / opening means) is connected to the DC
When 4 V is supplied, the first
The power supply line for supplying the power supply voltage to the thyristor circuit 11 is closed, and the operating contact FR of the short-circuit detection relay FR1 is closed.
When the DC 24V supply line is opened by the opening operation of 11a, the power supply line is opened and the supply of the power supply voltage from the No. 1 power supply to the load is stopped.

The no-fuse breaker NFB2 (second closing / opening means) is connected to the DC voltage generation circuit 15
When 4 V is supplied, the second
The power supply line for supplying the power supply voltage to the thyristor circuit 11 is closed, and the operation contact FR of the short-circuit detection relay FR2 is closed.
When the 24V DC supply line is opened by the opening operation of 21a, the power supply line is opened and the supply of the power supply voltage from the No. 2 power supply to the load is stopped.

The LED L1 is lit when the No. 1 power is supplied, the LED L2 is lit when the No. 2 power is supplied, and the LED L3 is lit when the load is supplied.

Next, the operation of this embodiment will be described.

The operation of the power supply switching circuit 10 shown in FIG. 1 will be described with reference to a timing chart shown in FIG.

First, as shown in FIG. 3A, the no-fuse breaker NFB1 is turned on in advance (operation contact NF
B11a is closed, and the recovery contact NFB11b is open), and the power switch S1 shown in FIG.
As shown in FIG. 1B, an AC voltage (100 V AC) from the No. 1 power supply (normal power supply) is supplied via the power transformer T1 to the first thyristor circuit 11, the first rectifier circuit 13, and the DC voltage generation. LEDL indicating that supply to circuit 15 is started and power is being supplied from No. 1 power supply
1 is lit. By the supply of the AC voltage from the first power supply, in the first rectifier circuit 13, the AC voltage is rectified to generate an excitation voltage, and the excitation circuits of the relays R11 and R12 are excited.

At this time, in the relay R11, when the exciting circuit is excited by the first rectifier circuit 13, its operating contact R
In addition to the fact that 111a to R113a move quickly to close (see FIG. 3C), the first rectifying circuit 13
When the excitation circuit is excited by the
a and R122a slowly move to close (see FIG. 3D), and the first voltage of the gate voltage generated by the first rectifier circuit 13 is reduced.
Thyristors SCR1 to SC in the thyristor circuit 11 of FIG.
When the supply to R4 is started, thyristors SCR1 to SC
R4 is turned on (see FIG. 9 (e)), the supply of AC voltage to the load is started, and the LED L3 indicating that the load is energized is turned on (see FIG. 9 (n)).

In the relay R11, when the excitation circuit is excited by the first rectifier circuit 13, the recovery contact R1
When the exciting circuit is excited by the first rectifier circuit 13 in the relay 12 while the relay 11b is opened, the recovery contact R121b is opened. Each of these recovery contacts R111b, R
With the opening of 121b, the gate voltage supply line from the second rectifier circuit 14 to the second thyristor circuit 12 is opened. That is, the AC voltage supplied from the first power source is the first
While the thyristor 11 supplies power to the load,
The second thyristor circuit 12 is not operated even when the power supply is turned on.

When each of the thyristors SCR1 to SCR4 in the first thyristor circuit 11 is turned on, the excitation circuit of the open detection relay RL in the open detection circuit 18 is excited, and the recovery contact RL1b is loosened and opened. (Refer to FIG. 7G). When the thyristors SCR1 to SCR4 in the first thyristor circuit 11 are turned on, the transformer CT for short-circuit detection in the first short-circuit detection circuit 16 includes:
Since the current I1 flowing from the thyristors SCR1 and SCR2 toward the load is offset by the current I2 flowing from the load toward the thyristors SCR3 and SCR4, and no induced current flows, the excitation circuit of the short-circuit detection relay FR1 is de-energized. The operating contact FR11a is open (see (f) in the figure).
Remains.

The above operations are normal operations after the first power supply is energized. Then, when the switch SW1 is turned on after the normal operation after the power supply of No. 1 (see (h) of FIG. 4), DC24V generated by the DC voltage generation circuit 15 is supplied to the reverse phase detection circuit 19, The excitation circuit of the reverse-phase detection relay RP is excited, and the recovery contacts RP1b and RP2b are closed, so that the reverse-phase detection function is enabled. The DC 24 V generated by the DC voltage generation circuit 15 is also supplied to the no-fuse breaker NFB2, and the no-fuse breaker MFB2T is turned on (see (i) in FIG. 3).

Next, when the power switch S2 is turned on (see FIG. 10 (j)), the AC voltage (100V AC) from the No. 2 power supply (standby power supply) is supplied to the second thyristor circuit 12 via the power supply transformer T2. The supply to the second rectifier circuit 14 and the DC voltage generation circuit 15 is started, and the LED L2 indicating that power is being supplied from the No. 2 power source is turned on. With the supply of the AC voltage from the second power supply, the AC voltage is rectified in the second rectifier circuit 14 to generate an excitation voltage, and the excitation circuit of the relay R2 is excited.

At this time, in the relay R2, when the excitation circuit is excited by the second rectifier circuit 14, the operating contact R2
1a moves quickly and is closed (see (k) in the figure). The second rectifier circuit 14 also generates a gate voltage.
The gate voltage supply line from the rectifier circuit 14 to the second thyristor circuit 12 is connected to the recovery contact R of the relays R11 and R12.
Since the gates are opened by opening the gates 111b and R121b, the supply of the gate voltage to the thyristors SCR5 to SCR8 is stopped, and the thyristors SCR5 to SCR8 are turned off.
This is the state (see FIG. 1 (l)).

The above operations are normal operations when the second power source is turned on after the first power source is turned on.

Next, assuming that the power supply of the No. 1 power supply is interrupted while the power supplies of the No. 1 power supply and the No. 2 power supply are both energized, the power switch S1 is turned off (see FIG. 7A), and the first thyristor circuit is turned off. 11, supply of the AC voltage from the first power supply to the first rectifier circuit 13 and the DC voltage generation circuit 15 is stopped, and first, the operation of the first thyristor circuit 11 is stopped (O
FF) (see (e) in the figure), and the LED L3 indicating that the load is being energized is turned off (see (n) in the figure). By stopping the supply of AC voltage from the first power supply,
The respective excitation circuits of the relays R11 and R12 become non-excited, and the respective operating contacts R111a to R113a of the relay R11 move quickly and are opened (see FIG. 3 (c)), and the recovery contact R11 is provided.
1b is quickly closed, and the respective operating contacts R121a and R122a of the relay R12 are loosely opened (see FIG. 3D).
Then, the recovery contact R121b is loosely closed.

Then, the recovery contact R111b of the relay R11
And by closing each of the recovery contact R121b of the relay R12,
The gate voltage supply line from the second rectifier circuit 14 to the second thyristor circuit 12 is closed, and the second rectifier circuit 1
4 th to 2 th thyristor SC in the second thyristor circuit 12
The supply of the gate voltage to R5 to SCR8 is started, and each thyristor SCR5 to SCR8 is turned on ((l) in FIG.
LED) that indicates that the supply of AC voltage from the No. 2 power supply to the load has started and the load is energized.
L3 is turned on again (see (n) in the figure).

Further, when each of the thyristors SC5 to SCR8 in the second thyristor circuit 12 is turned on, a potential difference of an AC voltage applied to the load leads to a short-circuit detecting transformer in the second short-circuit detecting circuit 17. A current flows to excite the excitation circuit of the short-circuit detection relay FR2, and the operation contact FR
21a moves quickly and is closed (see (m) in the figure).

The above operation is the operation at the time of the power failure of No. 1 power supply.

Next, when the No. 1 power supply is restored, the power switch S1 is turned on again (see FIG. 7A), and the power to the first thyristor circuit 11, the first rectifier circuit 13, and the DC voltage generation circuit 15 is changed. The LEDL indicating that the supply of the AC voltage from the No. 1 power supply has been resumed and the power is being supplied from the No. 1 power supply
1 is lit. By the supply of the AC voltage from the first power supply, the AC voltage is rectified in the first rectifier circuit 13 to generate an excitation voltage, and the excitation circuits of the relays R11 and R12 are re-excited.

When the excitation circuit of the relay R11 is re-excited, its operating contacts R111a to R113a move rapidly to be closed (see FIG. 9C), and the excitation circuit of the relay 12 is re-excited. Then, the operating contacts R121a, R1
22a is loosened and closed (see (d) in the figure), and the supply of the gate voltage generated by the first rectifier circuit 13 to each of the thyristors SCR1 to SCR4 in the first thyristor circuit 11 is restarted. Then, the thyristors SCR1 to SCR4 are turned on again (see FIG. 3E), the supply of the AC voltage to the load is resumed, and the LED L3 indicating that the load is energized is turned on (FIG. (N)).

In the relay R11, when the excitation circuit is re-excited, the restoration contact R111b is opened, and in the relay 12, when the excitation circuit is re-excited, the restoration contact R121b is opened. Each restoration contact R11
With the opening of 1b and R121b, the gate voltage supply line from the second rectifier circuit 14 to the second thyristor circuit 12 is opened again. Therefore, the thyristors SCR5 to SCR8 of the second thyristor circuit 12 are turned off ((l) in FIG.
The excitation circuit of the short-circuit detection relay FR2 in the second short-circuit detection circuit 17 is also non-excited, and its operating contact F
R21a moves quickly and is opened (see FIG. 9 (m)).

The above operation is an operation when the first power supply is restored.

Next, when any one of the thyristors SCR1 to SCR4 in the first thyristor circuit 11 opens and fails, the AC voltage supplied to the load from the first thyristor circuit 11 is stopped (FIG. 9E). At the same time, the LED L3 indicating that the load is being energized is turned off (see FIG. 3 (n)), the AC voltage applied to the open detection circuit 18 is also stopped, and the excitation of the open detection relay RL is excited. The circuit is de-energized, and the recovery contact RL1b of the open detection relay RL is loosened and closed (see FIG. 9G). The opening of the recovery contact RL1b of the opening detection relay RL causes the no-fuse breaker NFB1 to trip (O
FF) (see FIG. 3A), and the supply of the AC voltage from the first power supply to the first thyristor circuit 11 is stopped.

Then, the no-fuse breaker NFB1
The recovery contact NFB11b of the second rectifier circuit 1 is closed.
4, the gate voltage supply line from the second rectifier circuit 14 to the second thyristor circuit 12 is closed, and the supply of the gate voltage from the second rectifier circuit 14 to each of the thyristors SCR5 to SCR8 in the second thyristor circuit 12 is started. , Each thyristor SCR
5 to the SCR 8 are turned on (see (l) in the same figure), the supply of the AC voltage from the No. 2 power supply to the load is started, and the LED L3 indicating that the load is energized is re-lit (see FIG. FIG. (N)).

When the thyristors SC5 to SCR8 in the second thyristor circuit 12 are turned on, the second thyristors SC5 to SCR8 are turned on.
Current I3 flowing from the thyristors SCR5 and SCR6 to the load to the short-circuit detecting transformer in the short-circuit detecting circuit 17 of FIG.
Then, an induced current flows from the load toward the thyristors SCR7 and SCR8 by the current I4, and the short-circuit detection relay F
The exciting circuit of R2 is excited, and its operating contact FR21a moves quickly and is closed (see FIG. 9 (m)).

The above operation is performed by the first thyristor circuit 11
This is an operation when any one of the thyristors SCR1 to SCR4 has an open failure.

Next, when any one of the thyristors SCR1 to SCR4 in the first thyristor circuit 11 is short-circuited, the short-circuit detecting transformer CT in the first short-circuit detecting circuit 16 is turned off.
The current I1 flowing from the thyristors SCR1 and SCR2 to the load and the thyristors SCR3 and SC
Since the balance with the current I2 flowing toward R4 is momentarily lost and the induced current flows for a moment, the excitation circuit of the short-circuit detection relay FR1 is excited at this moment, and its operating contact F
R11a is closed only for a moment (see FIG. 11 (f)). The operation of the operation contact FR11a of the short-circuit detection relay FR1 causes the no-fuse breaker NFB1 to trip (OF).
F) (see FIG. 7A), and its operating contact NFB11a
Is opened, and the recovery contact NFB11b is closed. Also, at the same timing as the excitation timing of the short-circuit detection relay FR1, the open-circuit detection relay is de-energized only for one moment in the open-circuit detection circuit 18, and its recovery contact RL
1b is closed for a moment (see (g) in the figure).

At this time, the gate voltage supply line between the second rectifier circuit 14 and the second thyristor circuit 12 is closed by closing the recovery contact NFB11b, so that the second Supply of a gate voltage from the rectifier circuit 14 to each of the thyristors SCR5 to SCR8 in the second thyristor circuit 12 is started, and each of the thyristors SCR5 to SC
R8 is in the ON state (see (l) in the figure).

When each of the thyristors SC5 to SCR8 in the second thyristor circuit 12 is turned on, the thyristor SCR is connected to the short-circuit detecting transformer in the second short-circuit detecting circuit 17.
5, an induced current flows from a current I3 flowing from the SCR 6 toward the load and a current I4 flowing from the load toward the thyristors SCR7 and SCR8, thereby exciting the excitation circuit of the short-circuit detection relay FR2, and the operating contact FR21a moves quickly. (See (m) in FIG. 3). For this reason, the supply of the AC voltage from the No. 2 power supply to the load is started, and the LED L3 indicating that the load is being energized is turned on again (see FIG. 11 (n)).

The above operation is performed by the first thyristor circuit 11
This is an operation when any one of the thyristors SCR1 to SCR4 has a short-circuit fault.

Next, when any of the thyristors SCR5 to SCR8 in the second thyristor circuit 11 has an open failure, the supply of the power supply voltage from the No. 1 power supply to the load is continued without detection.

Next, when any one of the thyristors SCR5 to SCR8 in the second thyristor circuit 11 is short-circuited, the short-circuit detection transformer PT in the second short-circuit detection circuit 17 is activated.
The current I3 flowing from the thyristors SCR5 and SCR6 toward the load and the thyristors SCR7 and SC
Since the current I4 flowing toward R8 is out of balance and a potential difference is generated, the potential difference causes the short-circuit detection relay F
The excitation circuit of R2 is in the excited state, and its operating contact FR2
1a is opened (see (m) in the figure). The operation of the operating contact point FR21a of the short-circuit detection relay FR2 trips (OFF) the no-fuse breaker NFB2 (FIG. 1 (i)).
See). However, at this time, since the supply of the gate voltage from the second rectifier circuit 14 to the second thyristor circuit 12 is continued, each of the thyristors SCR5 to SCR8 is turned on.
The state is changed to the state (see (l) in the figure), and the lighting of the LED L3 indicating that the load is energized is continued (see (n) in the figure).

The above operation is performed by the second thyristor circuit 12
This is an operation in the case where any one of the thyristors SCR5 to SCR8 has a short-circuit fault.

FIG. 4 shows a table listing each operation in the power supply switching circuit 10 in each case.

In the power supply switching circuit 10 of the present embodiment, 1
A first thyristor circuit 11 including thyristors SCR1 to SCR4 whose ON / OFF control is performed on an AC voltage supply line between a power supply (normal power supply) and a load in accordance with the presence or absence of the power supply No. 1; A second thyristor circuit 12 including thyristors SCR5 to SCR8 that controls ON / OFF of an AC voltage supply line between a power supply) and a load in accordance with the presence or absence of a No. 2 power supply. Since an electronic power supply switching circuit using a thyristor is used as a semiconductor relay having a larger allowable current than a relay, an allowable operation range for an inrush current generated at the time of power supply switching can be expanded.

Further, the power supply switching circuit 10 of the present embodiment includes a short-circuit detection relay FR1 having an excitation circuit that is excited by a current flowing through the short-circuit detection transformer CT, and a thyristor in the first thyristor circuit 11 is provided. SCR1-SC
A first short-circuit detection circuit 16 for detecting a short circuit of R4;
Thyristor SC in the first thyristor circuit 11 is provided with an open detection relay RL having an excitation circuit which is excited by an AC voltage applied from the thyristor circuit 11 to a load.
An opening detection circuit 18 for detecting opening of R1 to SCR4;
The first short-circuit detection circuit 16 detects the short-circuit and the open-circuit detection circuit 18 detects the open-circuit.
And a no-fuse breaker NFB1 for tripping a power supply line to the thyristor circuit 11 of the first thyristor circuit 11.
The short-circuit fault and the open fault of R1 to SCR4 are reliably detected, and the switching operation between the first power supply and the second power supply can be reliably performed.

The power supply switching circuit 10 of the present embodiment includes a short-circuit detection relay FR2 having an excitation circuit that is excited by a voltage applied to the short-circuit detection transformer PT. Thyristor SCR5
Short circuit detecting circuit 17 for detecting short circuit of SCR8
And a no-fuse breaker NFB for tripping a power supply line from the power transformer T2 to the second thyristor circuit 12 by short-circuit detection by the second short-circuit detection circuit 17.
And the second thyristor circuit 12
The short-circuit failure of the thyristors SCR5 to SCR8 in the inside is surely detected, and the switching operation between the No. 1 power supply and the No. 2 power supply can be reliably performed.

Further, power supply switching circuit 10 of the present embodiment
In the case where the power supply wiring connected to the primary side of the power supply transformer T1 and the power supply wiring connected from the No. 2 power supply to the temporary side of the power supply transformer T2 are in phase, the phases are reversed by DC 24V supplied from the DC voltage generation circuit 15. When the detection relay RP is energized and its recovery contacts RP1b and RP2b are opened, and the wiring of the power supply is in the opposite phase, 24 V DC supplied from the DC voltage generation circuit 15 is lost and the anti-phase detection relay RP is de-energized. Then, the recovery contacts RP1b and RP2b are closed to detect the reverse phase, and an external negative phase detection lamp or the like is turned on to notify that the power supply wiring is connected in the reverse phase. By providing the phase detection circuit 19, the opposite phase connection of the power supply wiring is reliably detected and notified, so that the operator can deal with it.

Therefore, the power supply switching circuit 10 can secure operation stability by employing a thyristor, and can improve reliability by providing a circuit for coping with a thyristor failure. Further, the provision of the anti-phase detection circuit 19 allows the external power
The power supply switching circuit 10 can be provided with a function of detecting the reverse phase of the power supply wiring between the power supply and the power supply switching circuit 10, and the function of the power supply switching circuit 10 can be improved.

Although a traffic light is set as a load to which the power supply switching circuit 10 of the present embodiment is connected, if the traffic light is used in a railway, the allowable current from a mechanical relay is used as a power supply switching element. Thyristor S with large volume
CR1 to SCR8 are used and thyristor S
Since a detection circuit for detecting a short-circuit failure and an open failure of CR1 to SCR8 is provided, it is possible to prevent a signal signal from malfunctioning due to welding of contacts at the time of power supply switching, which hinders train operation control. That can be avoided.

[0071]

According to the power supply switching circuit of the present invention, an electronic power supply switching circuit using a switching element (for example, a thyristor or the like as a semiconductor relay) having a larger allowable current than a conventional mechanical relay. Therefore, the allowable operation range for the rush current generated at the time of power supply switching can be expanded.

Further, a first short circuit detecting circuit for detecting a short circuit of the first switching element, an opening detecting circuit for detecting the opening of the first switching element, a short circuit detecting and opening by the first short circuit detecting circuit A first closing / opening means for closing / opening a power supply line from the commercial power supply to the first switching element based on the opening detection by the detection circuit, whereby short-circuit failure and opening of the first switching element are provided. The failure can be reliably detected, and the switching operation between the normal power supply and the standby power supply can be reliably performed.

A second short circuit detecting circuit for detecting a short circuit of the second switching element, and a power supply line from the standby power supply to the second switching element is closed by detecting the short circuit by the second short circuit detecting circuit. And a second closing / opening means for opening / closing the second switching element to reliably detect a short-circuit failure of the second switching element and to reliably perform a switching operation between the normal power supply and the standby power supply. it can.

Further, an excitation circuit which is excited / de-energized by a composite voltage of a power supply voltage supplied from the normal power supply and a power supply voltage supplied from the standby power supply, and a contact which is closed / opened by the excitation circuit A reverse phase detection relay including a reverse phase detection relay having a reverse phase detection relay, wherein the operation of the reverse phase detection relay detects whether the wiring connected to the normal power supply or the wiring connected to the standby power supply is in reverse phase. By providing the phase detection circuit, the opposite phase connection of the power supply wiring is reliably detected and notified, so that the operator can deal with it.

As a result, the power supply switching circuit can secure operation stability by employing the switching element, and can improve reliability by providing a circuit for coping with the failure of the switching element. In addition, the provision of the anti-phase detection circuit allows the power supply switching circuit to have an anti-phase detection function of the power supply wiring between the external normal power supply and the standby power supply and the power supply switching circuit, thereby improving the function of the power supply switching circuit. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a power supply switching circuit 10 according to an embodiment to which a power supply switching circuit of the present invention is applied.

FIG. 2 is a diagram showing a relationship between an in-phase voltage waveform and an anti-phase voltage waveform detected by an anti-phase detection circuit 19 in FIG. 1;

FIG. 3 is a timing chart for explaining the operation of the power supply switching circuit 10 of FIG. 1;

FIG. 4 is a view showing a list of various operations of the power supply switching circuit 10 of FIG. 1;

FIG. 5 is a diagram showing a circuit configuration of a conventional power supply switching circuit.

FIG. 6 is a diagram illustrating an example of an inrush current generated when power is switched in the power switching circuit of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Power supply switching circuit 11 1st thyristor circuit 12 2nd thyristor circuit 13 1st rectifier circuit 14 2nd rectifier circuit 15 DC voltage generation circuit 16 1st short circuit detection circuit 17 2nd short circuit detection circuit 18 Open detection Circuit 19 Negative phase detection circuit CT Transformer for short circuit detection L1, L2, L3 LED NFB1, NFB2 No fuse breaker PT Transformer for short circuit detection R11, R12 Relay FR1, FR2 Short circuit detection relay RL Open detection relay RP Negative phase detection relay S1 , S2 power switch SW1 switch T1, T2 power transformer T3 transformer

Claims (1)

[Claims] 1. A first switching element for controlling a power supply voltage supply line between a normal power supply and a load in accordance with the presence or absence of a normal power supply, and a power supply voltage supply line between a standby power supply and a load. A second switching element for controlling the closing / opening of the first switching element according to the presence or absence of a standby power supply, and a first switching element for detecting a short-circuit failure of the first switching element.
A short-circuit detection circuit for detecting a short-circuit failure of the second switching element.
A short-circuit detection circuit, an open-circuit detection circuit for detecting an open failure of the first switching element, a short-circuit detection circuit connected between the service power supply and the first switching element, and a short-circuit detection by the first short-circuit detection circuit First closing / opening means for closing / opening a power supply voltage supply line between the normal power supply and the first switching element in response to an operation and an open detection operation by the open detection circuit; A power supply voltage supply line is connected between the power supply and the second switching element, and closes a power supply voltage supply line between the standby power supply and the second switching element in response to a short-circuit detection operation by the second short-circuit detection circuit. Second closing / opening means for opening / closing; an excitation circuit which is excited / de-energized by a combined voltage of a power supply voltage supplied from the normal power supply and a power supply voltage supplied from the standby power supply; An anti-phase detection relay having a contact that is closed / opened by the excitation circuit; an operation of the anti-phase detection relay determines whether a wiring connected to the normal power supply or a wiring connected to the standby power supply has a reverse phase; A power supply switching circuit, comprising: