First, frequent pre-charging can result in heat build-up on the pre-charge resistor and eventually burn-out. So set a minimum cycle, that is, for the resistance of the heat.
Second, frequent precharge and discharge, the life of DC bus capacitors are affected.
Precharge and motor frequently start and stop has nothing to do, it is mainly for the inverter input power off said. Is the SCR rectifier power supply, although you can not pre-charge resistance, but the second, the capacitor off life is also very interesting thing. Frequent charging and discharging can cause damage to the capacitor.
Logically, the rectifier part of the current margin is based on the inverter main circuit current to calculate the pre-charge current is much smaller, should not cause too much impact. Even to the thyristor rectifier circuit, the number of start-up can not be too much, the normal thyristor circuit starts normally not more than 6 times per hour, but not here to start normally, because the fan is not working at this time, coupled with the start A much larger current impact than a resistive inductive load, heat accumulation is inevitable, but only a little worse than the resistance.
Therefore, the rectifier part is also a factor.