Huabao Golden Samurai UPS Power 2020-8-10

· The power distribution room where UPS is placed is on the first floor of the workshop. The door of the room is often in and out. The outside is land and sand roads, so it is very dusty.

  1. Basic situation:

　　　　 (1) UPS specification: 80kVA.

　　　　 (2) Running status: stand-alone.

　　　　 (3) Customer name: a glass factory in Hebei.

　　　　 (4) The user describes the fault phenomenon: the control circuit board is damaged.

　 2. Site description

　　　　 (1) UPS external environment: temperature is 20°C; humidity is 40%;

　　　　Usage environment: The power distribution room where UPS is placed is on the first floor of the workshop. The door of the room is often in and out. The outside is land and sand roads, so it is very dusty.

　　　　 Placement space: The UPS is placed in the power distribution room of the workshop. The placement area is about 10 square meters. The two battery cabinets are placed on the left side of the UPS. Underground wiring is used. The wiring is reserved. The UPS can be moved for maintenance. The UPS is 20cm from the battery cabinet on the left, and the rear panel is 50cm from the wall. There are no obstacles on the front and right side, and the space is large.

UPS wiring: input and output live wires are red, green, and yellow wires with a cross-sectional area of 35mm2, the cross-sectional area of the neutral wire is 16mm2, the cross-sectional area of the battery wire is 35mm2, the input neutral wire is 35mm2, and the output has no ground wire .

　　　　 (2) UPS failure conditions

　　　　 found that the UPS was working in the bypass state after arriving at the scene. The fault light is on and the buzzer does not sound. The fault records are as follows: historical fault records: A phase temperature of 30°C, power rectifier component failure. Historical warning record: multiple charger failures.

　　　　 (3) Load operation

　　　　J load type: inverter speed motor.

　　　　K panel displays the load status: 8% (4.8kVA/4.8kW).

　　　　 (4) UPS power distribution

　　　　J Input voltage and frequency:

　　　　 Phase A: 229.4V/49.74Hz, Phase B: 229V/49.74Hz, Phase C: 229.7V/49.74Hz.

　　　　K zero-ground voltage: the zero-ground voltage at the input is 0.7V, and the output zero-ground voltage is 0.7V.

　3, maintenance process

　　　　 (1) Arrive at the user site and shut down the UPS to bypass mode. Open the maintenance cover and turn on the maintenance switch. Turn the UPS output MCB OFF, the mains input MCB OFF, and the battery MCB OFF.

　　　　 (2) Open the cover of the machine, first remove the dust, and thoroughly clean the dust inside the UPS. Visually inspect the internal components and connections of the UPS. There is a diode burst on the R-phase circuit board. Test the vulnerable parts with a multimeter, and found that many fuses were blown and there was a short-circuit of the transistor in the path of the fuse. The rest of the components are normal. Failures like this have occurred several times.

　　　　In accordance with the maintenance procedures, replace the faulty components and circuit boards, and then restart the machine. Add load after everything is normal. After the load is loaded, the mains inverter mode and the battery inverter mode are mutually converted 3 times and it is normal.

　4, failure analysis

　　　　 From the analysis of temperature and load, there is no problem. However, based on the fact that many fault points are detected and all circuit boards are covered by a thick layer of dust, it is suspected that it is caused by excessive dust.

　　　　 Because a large amount of dust is deposited on the surface of the printed circuit board, a poor conductive layer is formed, which disrupts the working order of the original control circuit and causes failure;

Due to the dust deposition layer, the external heat dissipation of the power triode is blocked, and heat accumulation is caused. In addition, the work disorder caused by the above reasons causes the triode to pass through. It may be because the PN junction of the triode is sintered together, and the flow capacity is It is very strong, so only the relevant insurance should be blown first.

　　 5. Conclusion

　　　　 (1) Because this UPS is the fourth failure this time, the failure phenomenon is almost the same, and it is caused by environmental reasons.

　　　　 (2) The room where the UPS is placed is dusty. It is recommended that the user establish an isolated room to prevent dust.

　　　　 (3) Due to the poor factory environment, it is recommended to increase the number of inspections and dust removal.