A: 1. Check if the parallel parameter settings of UPS are normal.
2. Check if the jumper cap on the parallel board of UPS is set according to the requirements.
3. Check which device in the parallel system has the alarm and replace the parallel cable for inspection.
4. If the UPS is three-phase input, check if the equipment is connected to the three-phase input source. If the single-phase input source is divided into three wires and connected to the equipment, it will cause three-phase imbalance in the equipment input, with current on the N wire, resulting in parallel failure.