Discuss 3 phase cable selection and protective devices in the Commercial Electrical Advice area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

0ld1e

-
Reaction score
0
Hi everyone.

I'm after abit of help calculating cables sizes and protective devices for a 3 phase DOL motor.
I haven't worked on 3 phase equipment for many years and 3 phase calculations is as far back as college so please excuse my ignorance on the subject and not knowing answers to perhaps basic questions.


Lets say for example we have a 3 phase 400v supply going to an induction motor. 5kw and a power factor of 0.8 and its on traywork.

would I be right in thinking the following.

5000/ (400* root3 * 0.8) = 9.02Amps per phase. 16.63A total ?????

table 4D4A BS7671 reference method E says 1.5mm 19Amps.

Sorry for this question but is the 19Amps the total the cable can carry overall or the total per phase?

How do I select the correct cable and 3 pole mcb from here?

I know there are other factor that come into play but can somebody please take me through the basic steps first so I can see how we get from start to finish then I would be happy to look at what other factor we need to consider.

Many thanks.
 
Hi Old1e. Welcome to the forum.
Look at the manufactures data sheets and they usually give you some info on what size protection you want to be looking at for the motor size you are using.
For a 5kw motor you will be looking about a 32A type C mcb.
 

Reply to 3 phase cable selection and protective devices in the Commercial Electrical Advice area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock