July 14, 2023
UPS is an uninterruptible power supply. Generally, it is one of engineering subsystems of low power machine room, which connects battery with main equipment, and is mainly used to ensure stable and uninterrupted power supply to equipment.
However, when using UPS power supply as protection for other objects, failures often occur on their own, resulting in inability to protect load.
A simple understanding of common UPS failures can help you deal with them more calmly when problems arise. The following are common UPS faults and troubleshooting methods and we will share them with you.
Question one:
Battery voltage is low but cannot be charged after several hours of charging after turning on battery
1. Check whether input and output voltage of charging circuit is normal;
2. If charging circuit input is normal but output is abnormal, disconnect battery and retest. If still abnormal, charging circuit is faulty;
3. If input and output of charging circuit is normal after disconnecting battery, it means that battery has been damaged due to long-term non-charging, over-discharging, or end of life. .
Question two:
When standby UPS is close to full load, utility power is good, but battery fuse blows when battery is powered
1. Is inverter defective?
2. Is battery voltage too low;
3. If battery voltage is too low, check if battery charging circuit is good;
4. If battery charging circuit is OK, check if battery voltage detection circuit is normal.
Question Three:
The UPS can only be powered by mains and cannot be converted to an inverter power supply
1. Is battery voltage too low and is battery fuse damaged;
2. If part of battery is OK, check if battery voltage detection circuit is OK;
3. If battery voltage detection circuit is normal, check if mains-to-inverter conversion control output is normal.
Question four:
The standby UPS works normally when utility power is available, and inverter works when utility power is off, but output voltage is low and transformer is very noisy
1. Check if power is normal;
2. If power is normal, check if output signal of pulse width output circuit is normal;
3. If output signal of pulse width output circuit is normal, check if output signal of drive circuit is normal.
Question five:
After turning on UPS, there is no display on panel and UPS does not work
1. Check if mains fuse is blown;
2. If mains input fuse is intact, check if battery fuse is blown, because some UPSs turn off all UPS outputs and display when battery voltage is not detected by itself;
3. If battery is in good condition, check if mains detection circuit is working normally. If mains detection circuit is not working properly and UPS does not have offline start function, UPS will turn off all outputs and displays.
4. If city detection circuit is working properly, check if battery voltage detection circuit is OK.
Question six:
When utility power is present, UPS output is normal, but when there is no utility power, buzzer beeps continuously and there is no output
1. Check battery voltage to make sure battery is not sufficiently charged. If battery is not sufficiently charged, check if battery itself or charging circuit is faulty.
2. If battery operating voltage is normal, check if drive circuit of inverter is normal. If output of drive circuit is normal, inverter is damaged.
3. If inverter drive circuit does not work normally, check whether signal generating circuit has a PWM control output. If there is a control output, it means that fault is in inverter drive circuit.
4. If signal generating circuit does not have a PWM control signal output, check if its output is blocked due to protection circuit, and if so, find out reason for protection;
5. If protection circuit does not work and operating voltage is normal, but signal generation circuit does not have PWM output, it means that signal generation circuit is damaged.
