Schneider UPS power supply common fault analysis

1. When there is mains power, the UPS output is normal, and when there is no mains power, the buzzer beeps for a long time and there is no output

Fault analysis: From the phenomenon to identify some problems of the battery and inverter, you can view it according to the following procedures:

1. Check the battery voltage to see if the battery is undercharged, if the battery is not charged enough, it is necessary to check whether it is the fault of the battery itself or the fault of the charging circuit.

2. If the battery operating voltage is normal, check whether the inverter drive circuit is working normally, and if the output of the driving circuit is normal, it means that the inverter is damaged.

3. If the inverter drive circuit is not working normally, check whether the waveform generation circuit has a PWM control signal output, and if there is a control signal output, it is clear that the fault is in the inverter drive circuit.

4. If the waveform generation circuit does not have PWM control signal output, check whether its output is blocked due to maintenance circuit operation, and if so, find out the maintenance reason;

5. If the maintenance circuit is not working and the operating voltage is normal, and the waveform generating circuit has no PWM waveform output, it is clear that the waveform generating circuit is damaged. The above troubleshooting order can also be reversed, which can sometimes detect problems more quickly.

Schneider UPS power supply common fault analysis

Schneider UPS power supply common fault analysis

Second, the battery voltage is low, but after more than ten hours of charging, the battery voltage still cannot be charged

Fault Analysis: To identify the phenomenon as a battery or charging circuit problem, you can view it as follows:

1. Check whether the input and output voltage of the charging circuit is normal;

2. If the input of the charging circuit is normal, the output is abnormal, disconnect the battery and retest, if it is still abnormal, it is a fault of the charging circuit;

3. If the input and output of the charging circuit are normal after disconnecting the battery, it is clear that the battery has been damaged due to long-term uncharged, over-discharged or expired.

3. A pair of power amplifier transistors in the power stage of the inverter are damaged, and after replacing the same type of transistor, the reason for the burning out after a period of operation is that the current is too large, and the reasons for the excessive current are:

1. Overcurrent maintenance failure. When the inverter output generates overcurrent, the overcurrent maintenance circuit does not work;

2. The pulse width modulation (PWM) component is faulty, the output of the two complementary waveforms is asymmetrical, one has a long on-time, and the other has a short on-time, which makes the operation of the two arms unbalanced, and even the two arms are turned on together, resulting in damage to the two tubes;

3. The parameters of the power tube are quite different, even if the symmetrical waveform is input, the output will be asymmetrical, and the waveform will be output through the transformer, resulting in bias magnetism, that is, the magnetic flux is unbalanced, and the accumulation leads to the transformer being full and the current increases suddenly, burning out the power tube, and one is burned out, and the other is also burned out.

Schneider UPS power supply common fault analysis

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