Just short explain of wiring

[sawo333]

Hello,

Can anyone quick explain me this?
Here in attachment there are screens of big motor where double power wires were use from frequency drive to motor terminal , i just want to know why it because bigger amperage needed to flow ? And if this same motor were used for star - delta switch by time relay , the jumper from motor had to be removed if we don´t want blow up fuses . Why actually on this motor it is no problem and you can have jumper here , i see not really big difference as if you have star delta switched motor with jumper , but here you can´t have jumper here on U1,V1,W1 and U2,V2,W2.

Thanks

 

[Andy_Reynolds51]

Motor with jumper bars looks to be delta connected but does not look like 185mm2 cable. Cable installation possibly using previous requirements considering distance etc. Now a vfd fitted using both cable for current capacity required.
Vfd parameters should be set with full load current corresponding to motor rating plate in delta configuration.

 

[westward10]

Your motor is 250kw so at flc you have approximately 400A. Sizing a single conductor for this current is putting you in the realms of 300.0 and above and the practicality of connecting such a csa becomes difficult. It makes sense in this case to use parallel conductors and your image shows parallel 150.0. Without assessing the full installation method and cable type 150.0 thermoplastic insulated conductors contained in conduit are rated at 216A, so two parallel conductors results in 432A.