Online UPS with wide input voltage range, high frequency, true online ... enoughcharge have short circuit, buzzer alarms for 20secs and UPS shut downautomatically.(OPT of time)Battery Lowvoltage short circuit protectionWhenunder ... -voltage have short circuit, buzzer alarms for 20secs and UPS shut downautomatically.(OPT of time) Uninterrupted Power Supply (High Frequency on-line UPS)