The delay is mainly in the main power supply to the standby power conversion. And some of the power equipment on the dual power automatic diverter switch conversion time is a strict requirement, so the dual power automatic diverter switch selection must look at the conversion time of the power equipment.
When the dual-supply automatic diverter switch has the function of self-input and self-recovery, the dual-supply automatic diverter switch should switch back to the main power supply after a delay when the main power supply resumes normal power supply.
Dual power automatic diverter switch is generally not allowed to switch with large motor or high inductive loads, such loads are switched in operation, when the phase difference between the two power sources is large, the motor will be subjected to huge mechanical stress. At the same time, the overcurrent caused by the counterpotential generated by the motor will cause the fuse to blow or the circuit breaker to deactivate. Therefore, when the dual power automatic diverter switch with a large motor or high inductive load conversion, the two sets of moving contacts in the conversion before a delay time should be increased, that is, should be used to delay the conversion of dual power automatic diverter switch, the delay time depending on the load to determine.
When the generator set is used as the emergency lighting power supply, the start of the generator and the whole time of power conversion should not be more than 15 s. The dual-supply automatic diverter switch should be used for the special type of "utility-generator conversion".
When the low-voltage distribution system in the transformer room is single-bus segmented operation, and the bus switch is set up, the total action time of the dual power automatic diverter switch should be matched with the action time set by the bus switch in the transformer room, and it should be greater than the action time of the contact switch by more than 0.5-1 second. The action time of the switch in the transformer room is mostly 2.5s, and the total action time of the dual-energy automatic diverter switch should be more than 3s.
Part of the load is allowed to interrupt the power supply time is as follows:
1. fire-fighting equipment (fans, pumps) power switching time ≤ 30s
2. emergency lighting of the normal power supply and the emergency power switching time should be met:
Evacuation Lighting ≤ 15s,
Backup Lighting ≤ 15s (financial commodities trading venues ≤ 1.5s)
Security lighting ≤ 0.5s
Design selection, should be based on the permissible power supply interruption time and the load characteristics of the selected dual power automatic switching switch total action time. The power supply and distribution system design code GB50052-95 article 2.0.4 stipulates, "self-transfer device action time to meet the permissible interruption of power supply time, can be selected with automatic input device independent of the normal power supply of the dedicated feeder line. Electrical Design Code for Civil Buildings, JGJ/T16-92, Article 3.1.9.2(2), "with automatic input device independent of the normal power supply of the dedicated feeder line for the permissible interruption of power supply time of 1.5s or more."
Allowable interruption of power supply time of 1.5s or less loads and important places (such as monitoring centers, etc.) of the emergency backup power supply, according to the "Code for Electrical Design of Civil Buildings," JGJ/T16-92, Article 6.3.1.2(2)-(3), should be set up uninterruptible power supply device.