Three phase motor help

[Zahid Nawab]

Hello all, I recently was asked to quote a three phase motor install within a pallet factory. To be honest, I was somewhat stumped in how to attack it as the sheer size and the control cabinet was gigantic. Although I'm mainly a domestic, commercial spark, this was somewhat out of my league. The motor was rated at 90kw, three phase, pf was 0.85, so current would of been around 150 amp per phase. The supply coming in was a 200amp, possibly 250 ( I don't remember exactly) and a standard three phase consumer unit. The control unit had an array of contactors and overloads, now I'm ok with motors and starters to a certain degree, ie forward reverse, on delay off delay, start delta, but this was out of my league. My questions are as follows as..
Would this require a separate circuit with a large type three phase isolator just for the motor? IE fed from a bussbar chamber.
Who would I need to speak to, IE in this regard as most sparks would struggle including myself, thank you in advance

 

[cliffed]

If it’s got it’s own control panel the isolator will be on tha….definitely a separate supply

 

[James]

Usually the machine manufacturer has done most of the work for you, on the machine nameplate or instructions will be the machine power requirements.

I.E. 400v 3ph 200A

solve it the same way you would approach any new circuit, calculate your cable size and ensure the isolator is able to accept both the current and the size of cable required.

as for a suitable breaker, some distribution boards allow for breakers in the 200A range, check with the manufacturor of the board.

if not, often a fused isolator is the easiest way to go and yes if there is a bus bar chamber feeding the boards then that may well be a suitable place to take the supply from.

 

[netblindpaul]

Just remember that the machine side is nothing to do with BS7671, & make sure that you are insured for 3ph machinery work, controls etc. & design as necessary.