r289是死的，出厂时即已确定，是变频器的极限电流。
P640是活的，这个P640的作用也是保护电机用的。P640的本意是可以人为调整变频器最大输出电流，以限制电机输出转矩，是用于转矩限幅的一个参数，一般情况下，它都足够大，即转矩限幅不起作用。它与r289没直接关系。不同的控制模式，不同的电机类型，系统在初始化时的结果不同。
For VECTOR the following applies (p0107):

p0640 is limited to 4.0 x p0305.

p0640 is pre-assigned for the automatic self commissioning routine (e.g. to 1.5 x p0305, with p0305 = r0207[1]).

p0640 must be entered when commissioning the system. This is the reason that p0640 is not calculated by the automatic parameterization when exiting the quick commissioning (p3900 > 0).

For SERVO the following applies (p0107):

p0640 is pre-assigned as follows using the automatic parameterization (p0340 = 1, p3900 > 0) taking into account the limits r0209 and r0323:

- for induction motors: p0640 = 1.5 x p0305

- for synchronous motors: p0640 = p0338