那个是进线电压，一般来说你必须设置为电网电压。否则可能导致低压报警或者DC电压不对。
你设为540或者640也可以是因为实际电网电压400V都在他们的60%以内，所以还没有报低压报警。这是一个很重要的参数：
Line volts
Line supply voltage for AFE (r.m.s. of line-to-line voltage)
This parameter specifies the incoming AC supply voltage.
It is used to calculate the setpoint DC link voltage (P125) and
the thresholds for fault messages "Line supply overvoltage",
"Line supply undervoltage" (P074) and "DC link undervoltage".