3 phase generator help

[yesitsashock]

Iv been asked to wire a separator (portable to go to different farms and separate water from slurry) to a 3phase 40 kva generator. The separator has 3 motors 11hp, 5.5 hp and 3hp. The 11hp motor kept tripping the gennys mcb so a previous spark fitted an adaptable box with contactors so it now starts up on star delta.
The genny is on a trailer and the 11hp motor pumps the Slurry upto the separator at the front of the trailer. The 11hp motor will be about 10-15m away from the trailer so he has asked me to make up an extension lead using swa and commando sockets as there could be livestock close by. The 11hp motor is protected by a 20amp ctype mcb, the 3hp motor has a 10amp mcb, the 5.5 hp motor is new. I couldn't see an Rcd anywhere on the genny.
The farmer went and bought 6mm 5 core swa and commando sockets before I got there.
As the 11hp motor is pulling about 11amps a 2.5 would be enough, it will have to be 7 core for the star delta, iv found 7 pin commando plug/sockets online.
He does want it hard wired because of the high risk of the cable getting damaged.
Would it be OK to solder a 2.5 earth onto the swa heat shrink it, and connect it to the commando male/female, then protect it with a 3phase RCD. Or go for a HO7 cable for extension lead..
Also anyone with advice for earthing for a portable genny would be helpful, it be attached to any other installation just the 3 3phase motors..
Thanks in advance

 

[davesparks]

SWA is unsuitable for making up trailing leads, it is not suitable for regular movement and flexing, you need flexible cable for this.

HO7-RNF flex is a heavy duty flex which may be appropriate.

I'm not sure you'll find a suitable commando plug/socket to do this, I don't think you can get a 7pin 400V/50Hz one.
The only 7 pin commando sockets I've seen have been the purple ones, which I think are for ELV.


If the cable is likely to get damaged then find a different route for it where it is not going to get damaged or provide protection for it.

 

[pc1966]

Could you move the star/delta starter to near the big motor and then just have the usual 4/5P red 400V connector for the overall supply flex?

 

[yesitsashock]

SWA is unsuitable for making up trailing leads, it is not suitable for regular movement and flexing, you need flexible cable for this.

HO7-RNF flex is a heavy duty flex which may be appropriate.

I'm not sure you'll find a suitable commando plug/socket to do this, I don't think you can get a 7pin 400V/50Hz one.
The only 7 pin commando sockets I've seen have been the purple ones, which I think are for ELV.


If the cable is likely to get damaged then find a different route for it where it is not going to get damaged or provide protection for it.

Thanks for the reply, iv sourced 32a ip67 6p+e sockets/plugs. Iv went with the swa it will be permanently fixed at the supply side and a commando socket at the load side, il have to solder the earth onto the swa.. its not ideal but the fact there could be live stock and with the way the plant has to be packed away swa should give it the best chance of not getting damaged.. it will be protected with a 30ma rcd..

 

[yesitsashock]

Could you move the star/delta starter to near the big motor and then just have the usual 4/5P red 400V connector for the overall supply flex?

Thanks for the reply.. Not an option unfortunately the other two motors are beside the genny so it would mean more cables going across the ground.