本帖最后由 td456 于 2010-4-14 12:28 编辑 + z) _9 K v. ^9 E; _& R a
' `2 [& H- H" aWe all know that if you want to change the rotation of a three phase AC motor. ! J2 d: `0 ^1 ~2 g# y+ `Just swap any of the two phase leads. " { h5 q. S+ n( s3 ~But for VFD application you need to do the swap after the inverter.* m' D$ Y6 w" T* k8 f( X8 X' R0 M: U: N
If you swap the leads before the inverter, it will not work.
Yes, Good point. 7 x" a+ |4 H! m) [8 l; |$ } }/ P8 D: L& X2 P6 B* GAs the principal of the VFD works, bascially from AC to DC, then DC to AC. 4 G) n+ A" T; l8 [) v0 n. u- y1 f5 X* G G; H
The phase rotation of the output of the VFD connecting to the motor is based on the sequence "open" or "close" controlled by the inverter pre-set inside; any changes to the phase rotation of the feeder will not affect the DC rotation, as DC is NO phase at all.- A( V7 ]/ X! U" j1 M! C1 [
' j4 g2 U6 a; u$ xThe only thing you can change the rotation of the motor is the output side of the VFD, NOT the input of the VFD.