Below you will find some useful links from the internet that may help you in your quest to pass the power pe exam.
The Art & Science of Protective Relaying by C. Russell Mason:
EPRI Power System Dynamics Tutorial by Electric Power Research Institute
ANSI Device Numbers - Numbers and Explanations by ABB
The NEC Challenge - NEC Questions & You can win money!
2008 NEC Code Tests - Older version of code, but still good for many of the questions & Free!
NEC Code Tips and Quizes - Around the middle of the page, there is a link for NEC Code Quizes.