Here is the NTPC entrance exam held at udaipur, rajasthan

This was held at Guru Nanak School.

NTPC Placement test / exam for B.tech engineering branch students from ECE – EEE – EIE (electronics), Electrical, mechanical, civil branches.

Technical test was not much tough (Instrumentation Stream)  
The written technical test paper has 120 technical questions.
The main ntpc placement test topics were:
Analog, Digital, Control, Process control, Electronic Meaurement and Industrial Measurement

(Also See other sample test questions for ntpc here)

The technical Test Questions:
1 Principle of Optical Fiber:     Total Internal reflection
2 Anticipatory controllers are;     Derivative
3 Routh Stability defines :  poles on the left/right/….
4 One question is on  Final Value theory
5 S^5+s^4+…….    : How many roots find out
6 System is Marginally stable – When root lies on
7 One 2 question on K-Map
8 9′s complement of 19
9 encoders and Decoders are different:   Number of Active lines
10 Flashing Memory is
11 Find out Hexadecimal code of 
12 Input Impedance of CRO is
13 Casacading of an Low pass and high pass filter will give : Notch filter
14 Pitot tube is used to measure
15 Why FET is used in Electronic Voltmeter?
16 Data Acqsition System Comprise of  Blocks:    Transducers,A/d conveter, sensors.
17 Some question on General Engineering
18 Ph changes from 5 to 7 Hydrogen Ion concentration will increase/decrease
19 2 Questions on feedforward control

As in other ntpc placement papers, there were also 50 aptitude and english questions. These are quite general (RS Agg. ones)
See more free NTPC Test papers and detailed latest sample paper questions with solutions / answers.