Emergency power, also known as EPS, specially designed for fire equipment and special load or lighting. When the power grid voltage is normal, the power supply of the power grid is directly supplied by the power supply to the load by the device. When the power grid power failure or power grid voltage lower than 15% or higher than 10% rated voltage, the device will switch to the inverter output power, the battery pack standby power by the inverter output current, continue to provide power to the load, when the grid voltage is normal, the device will return to the grid for power. In order to meet the need of fire emergency power supply, the equipment is equipped with a manual to start the emergency switch, and the battery pack is under the pressure protection.