How to troubleshoot UPS uninterruptible power supply

UPS uninterruptible power supply troubleshooting methods 1. The output of the UPS is normal when power is supplied, the buzzer is long, and there is no output when there is no power. Fault analysis: From the perspective of phenomenon, this is a partial fault of the battery and inverter. You can check it according to the following steps: Check the battery voltage to see if the battery is undercharged. If the battery is undercharged, check whether the battery itself is faulty or the charging circuit malfunction. If the battery working voltage is normal, check whether the inverter drive circuit is working normally. If the drive circuit output is normal, the inverter is damaged. If the inverter drive circuit is not working properly, check whether the waveform appearing circuit has a PWM control signal output. If there is a control signal output, it means that the fault is in the inverter drive circuit. If the waveform appearing circuit has no PWM control signal output, check whether its output is blocked by the protection circuit work, if so, find out the cause of the protection; if the protection circuit does not work and the working voltage is normal, and the waveform appearing circuit has no PWM waveform output, then the waveform Circuit damage has occurred. The above troubleshooting sequence can also be reversed, and sometimes the fault can be found faster. 2. The battery voltage is low, but the battery voltage is still not charged after charging for more than 10 hours after starting up. Fault analysis: Judging from the phenomenon, the fault of the battery or charging circuit can be checked according to the following steps: Check whether the input and output voltage of the charging circuit is normal; if the input and output voltage of the charging circuit is normal, the output is abnormal, disconnect the battery and re-test, if it is still abnormal , The charging circuit is faulty; after the battery is disconnected, whether the input and output of the charging circuit are normal, indicating that the battery has not been charged for a long time, has been over-discharged or has reached the end of its service life. 3. A pair of amplifier transistors of the inverter power stage are damaged. Replace the same type of transistors and burn out after running for a period of time. The reason is that the current is too large. The reason for the current is as follows: The overcurrent protection fails. When the inverter output has overcurrent, the overcurrent protection circuit does not work. The pulse width modulation (PWM) component fails, and the output of two complementary waveforms is asymmetrical. One lead time is long and the other lead time is short, which makes the two arms work unbalanced, and even the two arms lead at the same time, causing damage to the two tubes; power tube parameters The difference is very large, even if the input symmetrical waveform, the output will pass the asymmetrical waveform through the output transformer, causing magnetic bias, that is, the magnetic flux imbalance, the accumulation of the saturation transformer and the current impact, the power tube is burned, and one is burned out, and the other is also burned broken. 4. After the UPS is started, there is no display on the panel and the UPS does not work. Fault analysis: From the perspective of the fault phenomenon, the fault is in the power input, battery and power detection part and battery voltage detection circuit: check whether the power input fuse is burned out; if the main power input fuse is in good condition, please check whether the battery fuse is burned out , Because when the battery voltage can not self-check, some UPS will turn off all the output and UPS display. If the battery insurance is in good condition, check whether the power detection circuit is working properly. If the mains detection circuit is not working properly and the UPS has no mains startup function, the UPS will also shut down all outputs and displays. If the mains test circuit works normally, check whether the battery voltage test circuit is normal. 5. When the UPS is connected to the mains, the relay will hear repeated actions every time the UPS is turned on, and the battery voltage on the UPS panel is too low, the indicator light will be on and the buzzer will be on all the time. According to the above failure phenomenon, it can be judged that the failure is due to the low battery voltage, which causes the UPS to fail to start. Take out the battery, first perform balancing charge (all batteries are charged in parallel), if still unsuccessful, only replace the battery. 6. The standby UPS works normally when there is power, and the inverter outputs when there is no power, but the output voltage is low and the transformer is noisy. Fault analysis: The output of the inverter indicates that the final drive circuit is basically normal, and the noise of the transformer indicates that the two arms of the push-pull circuit are asymmetrical. Disclaimer: Some pictures and content of articles published on this site are from the Internet. 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