It would seem you have been in business a few yrs now if you have gone down the 3yr's course with apprenticeship some of you threads have a lack of say basic electrical knowledge..
You put a question to us without any info that would help us except the machine power demand and expect and answer when asked for more info we have to babyspoon feed what we require... you should do cable calcs routinely so should instantly realise the info we need.
Domestic commercial and industrial are all governed by the same reg's and calcs ...you seem like you have set up a business without any real time experience and then your finding yourself out of your comfort zone.. let me heed you a warning ..Don't go into the industrial sector without any experience its not as plain as it seems ...
Firstly we need to know:-
What is the machine - has it got associated large inrush current and if so do they have a long run up time.
What is the OCPD you are thinking of using? - this will have influence on the Zs requirements and can mean you require additional earthing or larger supply.
What wiring methods and wiring type (you have now told us)
You say the machine requires 75Kva then say 22kw... are you reading the plate correctly is the 22kw the plated motor size and the 75kw the FLC of the machine.
The fact is you can get all the cable sizing correct and the minute the machine is turned on power goes because you haven't allowed for the current/time curve of a 22kw motor with regards to your front end device.
I would personally get experience with someone with an industrial background for a few yrs before choosing this route ...dont get me wrong its a good route but a dangerous one if your doing no more than dipping your toe in it, this can have costly consequences that will sink any small business if you mess up and from your questioning it is clear your really out of your comfort zone especially with these bigger machines.
I fit machinery usually up to 150kw and knowing what i have learned i would never try to wing it without several yrs experience there are just too many things waiting to trip you up here... then once the machine is powered they always ask you to figure out why part of it don't work thats when your competence will be questioned - saying its powered and thats all you know is one thing getting them up and running and explain why it wouldn't work is when you become invaluable and guaranteed future work.
Take this as good advice and not an attack on your competence you just lack experience but you can't wing it like you can in domestic.
