UPS and EPS have similar functions, but it does not mean they can be replaced. UPS is mainly used in places with relatively stable mains power and is suitable for high-precision instruments. EPS is mainly used for fire protection and must have fire certification. It mainly carries inductive loads such as pumps. UPS does not have fire certification and cannot pass the fire inspection. EPS is somewhat similar to a backup UPS, where the inverter does not work normally and the battery is only put into operation when the mains power is cut off. Generally, the power supply is not subjected to constant current or constant voltage processing. Usually, contactor conversion is used, with a switching time of 0.1~0.25. Its advantages are simple structure, low cost, low energy consumption and no noise during normal operation. It can adapt to inductive, capacitive and comprehensive loads, and can achieve variable frequency soft start when needed.
When there is mains power, APC UPS charges the battery, and when there is a power outage, it supplies power to the load through the battery; EPS uses mains power to supply power while charging the battery, and supplies power to the load through an inverter when there is no mains power (power outage). Differences: UPS power supply will not interrupt the load’s electricity consumption during a power outage, while EPS power supply will temporarily cut off the load’s electricity consumption before switching to battery power supply (through an inverter) during a power outage. Usage: UPS is mainly used in places where sudden power outages are not possible, such as at subway station gates (entrance and exit ticket machines); EPS is mainly used in emergency lighting, such as lighting in some public places. In order to avoid panic caused by sudden power outages, EPS lighting is needed.
UPS(UninterruptiblePowerSystem/UninterruptiblePowerSupply)， Uninterruptible power supply is a system equipment that connects a battery (mostly lead-acid maintenance free battery) to a host and converts DC power into mains power through module circuits such as host inverters
Application: Mainly used to provide stable and uninterrupted power supply to a single computer, computer network system, or other power electronic equipment such as solenoid valves, pressure transmitters, etc
The EPS (Emergency Power supply) emergency power system mainly includes rectifier charger, battery pack, inverter, interlocking device, and system controller. Emergency power supply can provide power to various electrical equipment in different situations during power outages.
Application location: In emergency accidents, lighting and other power plants, it has a higher cost performance ratio compared to UPS uninterruptible power supplies with lower conversion efficiency and long-term continuous operation.
Principle:
(1) UPS – When the mains input is normal, the UPS stabilizes the mains voltage and supplies it to the load for use. At this time, the UPS is an AC mains voltage stabilizer, and it also discards power to the internal battery:
When the mains power is interrupted (accident power outage), UPS immediately supplies 220V AC power from the battery to the load through inverter switching conversion method, so as to maintain normal operation of the load and protect the load software and hardware from damage.
UPS equipment usually provides protection against high or low voltage.
(2) EPS – When the mains power is normal, it supplies power to important loads through the switching device, AC bypass, and transfer switch (bypass static switch), while conducting mains power detection and charging the battery; Under the control of the EPS logic control board, the inverter stops working and is in an automatic shutdown state. At this time, the charger only provides a low-power DC power supply equivalent to 10% of the capacity of the battery pack (Ah), and does not have the ability to directly deliver DC power to the inverter. EPS works in a sleep state to achieve energy-saving goals.
When the mains power is interrupted or the mains voltage exceeds the rated input voltage (± 15% or ± 20%), the interlocking device will immediately switch to the inverter power supply and provide DC power to the battery pack.
When the mains voltage returns to normal operation, the control center of EPS sends a signal to perform automatic shutdown operation on the inverter, and also switches from inverter power supply to AC bypass power supply through its transfer switch. Afterwards, EPS provides mains power to the load through the AC bypass power supply path and also charges the battery pack through a charger.