UPS is Uninterruptible
The abbreviation of Power Supply is what we often call UPS uninterruptible power supply | voltage stabilizer. The common UPS power supplies on the market are mainly online (OnLine) and backup (OffLine).
EPS emergency power system is the abbreviation of Emergency Power Supply, which is an emergency power supply that meets the special requirements of the fire protection industry.
1. The backup UPS directly supplies power from the mains to the load when the mains is normal. When the mains exceeds its working range or power failure, it is converted to the battery for inverter power supply through the transfer switch. Its characteristics are: simple structure, small size, low cost, but narrow input voltage range, poor output voltage stability accuracy, switching time, and the output waveform is generally square wave
2. The online interactive UPS directly supplies power from the mains to the load when the mains is normal. When the mains is low or high, it is regulated by the UPS internal voltage stabilization circuit and then output. When the mains is abnormal or power outage, it is converted to The switch turns to battery inverter power supply. Its characteristics are: a wide input voltage range, low noise, small size, etc., but there is also a switching time.
3. When the mains is normal, the online UPS is rectified by the mains to provide DC voltage for the inverter to work, and the inverter provides AC to the load. When the mains is abnormal, the inverter is powered by the battery, and the inverter The device is always in working state to ensure uninterrupted output. Its characteristics are that it has an extremely wide input voltage range, basically no switching time, and has high output voltage stability and accuracy. It is especially suitable for occasions with high power requirements, but the cost is high. At present, almost all UPSs with power greater than 3KVA are online UPSs.
UPS also has functions such as voltage regulation and filtering. Some UPSs can be powered by the mains bypass in case of failure or overload.
The voltage output of the backup type has large fluctuations. Between 170V and 260V, the high-speed relay is used to realize the conversion between the mains and the battery, and the conversion time is less than 10 milliseconds. The online type always uses the inverter circuit to work, and its voltage stability is high, basically within the range of 220V±5%, and there is basically no conversion time for the battery; the static switch is used for the bypass conversion with the mains, and the conversion time can reach microseconds class.
UPS has high output precision, fast conversion time, high cost (about twice that of EPS), high energy consumption (online), and short mainframe life (8-10 years).
EPS is somewhat similar to a backup UPS. Usually, the inverter does not work, and the battery is only put into use when the mains is cut off. Generally, the constant current and constant voltage are not processed for the power supply. Usually a contactor is used for conversion, and the switching time is 0.1 to 0.25S. Its advantages are simple structure, low cost, low energy consumption and no noise at ordinary times, long life of the host (15-20 years), suitable for inductive, capacitive and comprehensive loads, and variable frequency soft start can be realized when needed.