A brief analysis of the automatic feeder for standby power supply
The standby power automatic input device refers to a device that can automatically quickly and accurately put the standby power into the electrical equipment or switch the equipment to the standby power supply when the line or electrical equipment fails, so as not to let the user lose power. Its content is shown in the image.
In the mode of operation of the power inlet. Among them, the main power supply and standby power supply mode refer to a set of power supply system, the main power supply is responsible for the main power supply task, and the standby power supply takes over the power supply of the main power supply when the main power supply fails. The mutual standby power supply mode refers to the two sets of power supply systems, the two sets of power supplies are the main and standby of each other, and when one of the power supplies fails, the other power supply can take over its power supply work. This approach requires both power systems to be able to meet the power needs of the equipment and to be able to switch quickly.
Mains power supply and standby power supply.
The APD wiring is shown in the diagram.
When the main power supply incoming line is powered off due to failure, the loss of voltage protection action will make the 1QF jump.
Brake, time relay kt power loss, its contacts delay opening, so in it.
Before opening, close the contactor km
After receiving power, the closing coil Y0 of 2QF is energized and the backup power supply is put in. Under normal operation, when the main power supply is faulty and the power is off, the closing contactor KM is energized to make the circuit breaker 2QF close, and the system automatically switches to the standby power supply to maintain the stable operation of the power system.
When the first circuit is working, the second circuit is standby, 1QF is in the closing position, and 2QF is in the tripping position.
When 1WL is working, 2WL is standby. 1qf in the closing position, 1sa of the "no-pass" pass. The auxiliary contacts of the 1QF are normally closed and normally closed. 2qf in the tripped position, 2sa in the off position. When the power supply side of 1WL is powered off due to fault, the voltage relay 1kv, 2kv normally closed contact is closed, 1kt action, delay closing contact delay closing, so that the trip coil 1 y r of 1qf is energized, then 1qf trips.
1QF) contacts closed, 2QF closing coils 2Y0 via 1s A) contacts. 1qf). to 4ks. 2km NC contacts. 2qf). Then power on the small bus WC, close the 2QF, and in the closing circuit, the contact in the virtual frame is the exit relay contact of the other party's circuit breaker protection circuit. For latching. 2QF is closed, so that the backup power supply 2WL is automatically put into operation, and the power supply of the substation is restored. Again, when the above phenomenon occurs in 2WL, the same is true for the action.
Requirements for automatic feed-in devices for standby power.
Article 1. When the operating power supply disappears for any reason, a p d should be able to operate. For example, in the event of a malfunction or misoperation, the operation can be guaranteed.
Article 2. It should be ensured that the standby power supply is put into standby power only when the standby power supply voltage is normal after the working power supply is disconnected. Ensure the stability and continuity of the system.
Article 3. The standby power automatic input device allows only one operation.
The main reason is that when the working bus has a permanent fault and is not cut off by the outgoing circuit breaker, due to the decrease in the voltage of the working bus, the device acts, and the standby power supply or standby equipment is put into operation for the first time, because the fault still exists, the relay protection on the standby power supply or standby equipment will quickly disconnect the standby power supply or standby. If the backup power supply or backup equipment is put into use again at this time, not only will it not be successful, but it will also cause the backup power supply, backup equipment, and system to suffer another failure impact, which may cause serious consequences such as expansion accidents and damage to equipment.
Article 4. When the secondary circuit of the voltage transformer is disconnected, a p d should not malfunction.
Article 5. In the case of a p d, the standby power overload and motor self-starting should be checked. If the overload is severe or the motor cannot be guaranteed to start automatically, the load should be automatically reduced before the A P D action.