A Case Retrofit of PLC-based Dual-source Automatic Switch
Dual-source automatic switch is mainly used to ensure normal power supply of Class Ⅰ and Class Ⅱ loads,and is mostly achieved through PLC.When one of the sources encounters an outage,supply for the load formerly rely on that source can be automatically switched to another source,thus ensuring continuous and reliable operation of Class Ⅰ and Ⅱ loads.However the malfunction of this switch can also lead to power loss to the loads or form an inter-source short circuit fault.This paper reports a case of technical retrofit performed on the dual-source automatic switch system for the low-voltage distribution in an actual metro project in Guangzhou.