JPS5947529B2 - Bus bar automatic switching system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic bus switching system for a bus whose load is a transformer motor or the like connected to two different power sources.

The conventional bus line cutting method will be explained with reference to FIGS. 1 and 2.

Figure 1 is an operational system diagram, in which the breakers 3 and 4 are always closed, the breakout switch 5 is always open, and the power supplies 1 and 2 are
It is assumed that power is received from the grid power source and is supplied to the loads 9 and 9'. Note that 6.T is a bus line, respectively. Now, in a system that secures power by automatically opening the breaker 3 and closing the breaker 5 when the power source 1 loses power,
The magnitude and phase of the voltage on the bus 6 due to the residual voltage of the motor connected to the load 9 and the voltage on the bus 1 on the healthy power supply side are detected by the voltage transformers 8 and 8' connected to the respective buses. The signal is then input to the synchronous relay 10 and compared to determine whether automatic switching should be performed. As a specific method for this determination, as shown in FIG.
The detection range 11 is set so that the bus voltage 12 on the healthy side input to the relay 10 and the voltage 13 on the bus 6 on the power loss side due to the residual voltage of the motor are synchronized for a certain period of time (synchronization time). If it is within detection range 11, synchronous relay 1
0 issues an automatic switching command. or,
Conversely, when the power supply 2 loses power, it automatically switches off the breaker 4.
Similarly, the power supply is secured by setting the power supply to "open" and the breaker 5 to "closed". However, depending on the magnitude and phase of the residual voltage, if automatic switching is performed, a large electromagnetic force may be applied to the switched load on the bus side, resulting in damage. The synchronization detection range 11 is determined by taking into account the time from when a command is issued by the relay 10 to when the mustard cutter 5 is turned on.

This conventional method has the disadvantage that the synchronization detection range 11 is limited and the time from synchronization detection to bus switching is short, and therefore there is very little chance of automatic switching. Become.

Therefore, an object of the present invention is to obtain an automatic bus switching system that uses a plurality of synchronous relays and has a plurality of synchronous detection ranges to widen the detection range and increase the chances of automatic switching.

The present invention will be explained below with reference to the drawings.

FIG. 3 is a diagram when two synchronous relays are used and two synchronous detection ranges are set. In other words, the bus voltage 1 on the power loss side
3 is outside the closing possible range 14, the newly installed synchronous relay detects the magnitude and phase of the voltage within the synchronous detection range 15, and the synchronous relay issues an automatic switching command and the mustard breaker 5 is activated. Taking into account the time it takes for the bus to be turned on, the busbar switching is performed within the possible turn-on range 14. The method for detecting in the synchronous detection range 15 is to use another synchronous relay that is the same as that used in the synchronous detection range 11,
As shown in FIG. 4, it is only necessary to reverse the phases of the input voltages to the synchronous relay 10 and the other synchronous relay 17 so that they are shifted by 180 degrees. As another example, we will discuss a method in which three synchronous relays are used to further expand the synchronous detection range.

That is, as shown in FIG. 5, synchronous detection ranges 11, 18, and 19 are set by three synchronous relays. in this case,
As shown in FIG. 6, the same synchronous relays 10, 20, and 21 may be used, and the input voltages may be shifted by 120 degrees and 2401 points, respectively, with respect to the synchronous relay 10. As shown in FIG. 7, the command for automatic switching is as follows:
When the contact 22 becomes 0N due to the operation of
It is generated when the condition of N is combined with the condition of ON of the contact 24 due to the operation of the synchronous relay 21 in the synchronous detection range 19. Note that Xl and X2 are auxiliary relays. In this case, it is not that the chance of automatic switching is tripled because there are now three synchronous relays, but that automatic switching can be performed safely regardless of which bus bar is being switched. A synchronous relay can be used for this purpose. As explained above, by using multiple synchronous relays, the chances of automatic switching are greatly increased compared to when using one synchronous relay, and this greatly improves the reliability of the plant. Benefits can be obtained.

[Brief explanation of drawings]

Figure 1 is an operational system diagram for automatic bus switching, Figure 2 is a diagram for explaining synchronization detection using one conventional synchronous relay, and Figures 3 and 5 are diagrams showing multiple synchronous relays according to the present invention. Figures 4 and 6 for explaining synchronization detection using
The figure shows the connection of input voltage to a synchronous relay when using a plurality of synchronous relays of the present invention, and Fig. 7 shows synchronization detected using three synchronous relays according to an embodiment of the present invention, It is a figure which shows the sequence which issues the command of bus bar automatic switching. 1, 2...Power supply, 3, 4, 5...Shipping switch, 6,7...Bus bar, 8,8'...
Potential transformer, 9, 9'...Load, 10, 17
,20,21...Synchronous relay, 11,15,1
8, 19...Synchronization detection range, 12...
Bus voltage on healthy side, 13... Bus voltage due to residual voltage on power loss side, 14... Closing range of circuit breaker 5 that is capable of passive switching.

Claims (1)

[Claims] 1. Two system buses that are connected to different system power sources and supply power to separate loads, a bus interconnector or disconnector that connects these two system buses, and a bus interconnector or disconnector that connects to the system bus and controls the power receiving voltage of the system. In the automatic bus switching system, which is connected to the instrument transformer, the electrical angle phase of the secondary voltage of the instrument transformer is changed to 360/n.
A displacement circuit that displaces the voltage by degrees (n is an integer of 2 or more), n synchronous relays connected to the instrument transformer via this displacement circuit, and automatic switching commands output from these synchronous relays. An automatic bus switching system comprising a closing time adjustment circuit that adjusts the time according to the degree of the displacement.