What is the difference between UPS and EPS?

(1) The development of EPS in our country originated from the need to ensure power supply and enable coordination with fire-fighting efforts in the event of sudden grid failures. It can provide immediate lighting for evacuation and emergency fire-fighting capabilities, thereby protecting people’s lives and bodies from harm. The technical requirements for such products are supervised by the fire safety certification authorities under the Ministry of Public Security, and they must also pass fire safety inspections at the installation site. UPS is merely used to protect users’ equipment or businesses from financial losses, and its technical specifications are certified by the Ministry of Information Industry. The safety standards applicable to the two are significantly different, resulting in different sets of values. (2) Both EPS and UPS can provide two separate output power supplies; to ensure high-quality power supply, UPS gives priority to the inverter option ； And EPS prioritizes mains power to ensure energy savings. Of course, there are differences between the two in terms of the design specifications for rectifiers/chargers and inverters. (3) Since UPS is used in an online mode, it can issue alerts promptly in the event of a failure, and with mains power as a backup, users can quickly become aware of the issue and resolve it, thereby preventing greater losses from occurring. EPS is used offline and serves as the final power supply backup; therefore, its reliability design requires higher standards. It cannot be simply regarded as a backup UPS, as doing so would undermine the importance of EPS. If the EPS cannot be powered by batteries in case of a power failure, it is essentially useless, and the consequences would be disastrous. (4) UPS power is supplied to computers and network devices, and the nature of the load (input power factor) varies little; therefore, national standards specify that the output power factor of a UPS should be 0.8. The purpose of EPS power supply is to ensure electricity supply and fire safety; the loads involved can be inductive, capacitive, or rectified nonlinear loads. As a result, its output power factor cannot be set at 0.8 (national standards for EPS specify this value). Moreover, some loads begin to operate only after the main power is cut off, which requires EPS to be able to provide a large inrush current. Therefore, EPS needs to have good dynamic performance and stronger overload resistance. Therefore, the technical design specifications for the various components of EPS and UPS are different.

EPS is a fire emergency power supply that starts up in the event of a power outage; there is a delay before it activates, and it has a large capacity as well as a long backup time. It is not operational while electricity is available, with the charger charging the battery pack during those times. Generally, the voltage of the battery pack after it is connected in series is over 500 V. UPS is an uninterruptible power supply; the switching time is in the millisecond range, so there is no interruption, and its capacity is not very large – it generally cannot provide backup for a long period of time. Regardless of the external power supply, it operates in rectification and inversion mode. A few manufacturers also use an interactive mode.

UPS is used for instruments, requiring high performance and short switching time, while EPS is used for emergency lighting, with lower requirements and a longer switching time