Diesel generator Causes of unstable operation in the "Mains - generator --UPS" power supply systems, UPS circuit structure determines its input non-linear characteristics. The most typical is the traditional double conversion online UPS, because of its input side AC / DC converter is a rectifier filter circuit, its input current is a pulsating current, not only low input power factor (0.7 a 0.8), also includes a large number of high harmonic current (30% to 40%). Low input power factor and harmonic currents will be through the emotional resistance generator stator coil, stator coil resistance due generators greater than the short-circuit impedances of power transformers, generators and therefore more susceptible to non-linear loads, ie in the same load Under current waveform distortion (THDI) case, the voltage waveform distortion (THDI) is greater than the transformer. At the same harmonic current to the generator significantly increased loss (hysteresis loss is proportional to the current frequency, frequency eddy current loss ratio in the square and the wire current skin effect), and makes the generator output voltage waveform distortion significantly increased big, seriously affect the normal operation of the generator. In addition, step changes in load, UPS front-end filter provides capacitive currents are the main cause of the generator set is not working properly. For example, a generator room configuration and double conversion on-line UPS systems and measuring tape found generator load factor reached 70%, the input terminal of the current waveform distortion 4.8%, the generator load power factor is capacitive ahead at 0.93, when the generator load UPS will have a "bypass power phase is exceeded, degraded, bypass unavailable" and warning alarm, while display data generator reactive power changes greatly. Diesel generator - Weifang Power Equipment Manufacturing Co., Ltd. Yamato www.yamajizu.com