a back-up power supply

• 备用电源

a back-up power supply的用法和样例：

例句

1. With the application of SOFC as large-scale power plant, at the same time, the demonstrating projects of SOFC as distributing power and standby power supply expand quickly.
   在发展大型电站技术的同时，固体氧化物燃料电池作为分布式电站和备用电源技术及示范工程蓬勃开展。