please teach me how to use a megger to check the motors and cables effectively?

 

I am unclear from your question whether you know how to use a megger or not, or are you looking to find information specific to motors and cables.

A starting point would be Volume 1 - Chapter 8.7

You could also look through a site search to see if this has been covered elsewhere.

Otherwise, you will need to be a little more specifoc, i.e. what exactly is causing you problems, and can you give practical examples of where your misunderstanding arises.

Dave