·UPS Common Faults and Exclusion Method
1. there is electricity when the UPS output is normal, and there is no electricity output when the buzzer sounding.Failure Analysis: From phenomena it can be determined that the battery and the inverter is the part of the failure, according to the following procedures check:
1) Check the battery voltage, battery is charged enough to see if the battery charging less, they should check their own fault or the battery charging circuit faults.
2) If the battery voltage is normal, check whether the inverter drive circuit is working properly, if the driver circuit output is normal, it can indicates that inverter is damaged.
3) If the inverter drive circuit is not working properly, then check the output the PWM waveform generation circuit controlled signal, if control signal is output, it can indicate fault in the inverter drive circuit.
4) If there is non-PWM waveform generation circuit control signal output, then check whether the output protection circuit is work to blockade, if so, please identify the protection reasons;
5) If the protection circuit and operating voltage did not work properly, while the waveform generation circuit without PWM waveform output is illustrated, the waveform generation circuit can be damaged.
Therefore, the row can also be reversed in order to conduct, and sometimes must find fault faster.
2. battery voltage is low, and even after charging more than 10 hours, battery voltage cannot be recharged .
Failure Analysis: From phenomena to determine the battery or charging circuit failure, according to the following steps to check:
1) Check whether the charging circuit input and output voltage is normal, if the charging circuit input is normal, and the output is not normal, disconnect the battery and then test, if not normal, it can be identified as charging circuit fault;
2) If the disconnect battery charging circuit after the input and output are normal, then it shows that battery has no charge for a long time, over-discharge or have other reasons of damage to the life.
3. a pair of inverter power stage transistor amplifier is damaged, replaced by the transistors of the same model, after running for some time and burn because the current is too large, the reasons causing too much current causes are:
1) over-current protection failure. Occurred when the inverter output current, the overcurrent protection circuit does not work;
2) pulse-width modulation (PWM) component failure, the output of the two-way complementary waveform in asymmetry, a turn-on for a long time while the other lead-time is short, so that arms imbalance in the work, and even arms the same time, conduction, resulting in two-side damaged;
3) The difference between the large power transistor parameters, even if input in symmetrical waveform, the output will be asymmetric, the waveform through the output transformer, causing magnetic bias, that is, the magnetic flux imbalance, leading to accumulation of down transformer saturation current surge, burn Power tube, and a burned-out, the other also will be burned.
4. Initiate UPS, the panel has no display, UPS does not work.
Failure Analysis: judge from its failure in the mains input, battery and mains detection part and the battery voltage detection circuit:
1) Check whether the electricity supply input fuse is burned, if the mains input fuse intact, check whether the battery insurance is burned, because some UPS when the battery voltage is less than a self-test, the UPS will shut down all the output and display;
2) If the battery insurance intact, check the mains detection circuit is working properly, if the municipal power detection circuit is not working properly and UPS do not have the start function without electricity, UPS also will turn off all output and display.
3) If the municipal detection circuit is working correctly, then check whether the battery voltage detection circuit is normal.
5. in the case of access to electricity, each time you open UPS, it can be heard the sound of relay repeated movements, UPS battery low indicator panel light and buzzer ringing long.
Based on the above phenomenon failures can be judged: the failure by the battery voltage is too low, resulting in false starts caused by UPS.
Remove the batteries before a balanced charge (all batteries in parallel to charge), if not successful, it can only be saved by replacing the battery.
6. a back-up UPS is working correctly when there is electricity, when there is no electricity the inverter has output, but the output voltage is low, while issuing a larger transformer noise.
Failure Analysis: Inverter output instructions are basically normal last stage driver circuit, transformer the noise of arms shows the work of asymmetric push-pull circuit, testing the following steps:
1) Check whether power is normal, if the power is normal, and then check whether the pulse-width output circuit output signal is normal;
2) If the PWM output circuit output is normal, then check whether the drive circuit's output is normal.
7. open UPS when the electricity supply in the city is normal, inverter working lights flashing, intermittent buzzer sounds, UPS inverter can only work in the state, and cannot be converted to electricity working condition.
Failure analysis: power inverter cannot be converted to electricity supply shows that electricity supply to the inverter power conversion portion of the fault, we should focus on detection:
1) whether the electrical input fuse is damaged, if the mains input fuse is intact, check whether the mains rectifier filter circuit output is normal;
2) If the electricity output of the rectifier filter circuit is normal, check whether power detection circuit is normal;
3) If electricity detection circuit is normal, and then check whether the inverter power supply to the electricity supply switching control output is normal.
8. When the load of off-UPS close to full load, the electricity supply is normal, while the battery power supply fuse is fusing.
Failure Analysis: battery fuse fusing, indicating battery-powered flow is too large. The detection can be the following steps:
1) whether the inverter is breakdown;
2) whether the battery voltage is too low, if the battery voltage is too low, and then testing whether it is normal battery charging circuit;
3) whether the battery charging circuit is normal, and then test battery voltage detection circuit is working properly.
9. UPS can only be supplied by the municipal electricity but not inverter supply.
Failure Analysis: that cannot convert electricity to the inverter power supply shows that electricity supply to convert part of the inverter fails, we should focus on detection:
1) The battery voltage is too low, battery fuse is intact, if the battery part is normal, checking whether the battery voltage detection circuit is normal;
2) If the battery voltage detection circuit is normal, and then check whether the electricity supply to the inverter switching control output are normal.
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