Electrical Machines - Special Purpose Machines

Special Purpose Machines - IAS previous year questions......

1.  which one of the following can be obtained by the equivalent circuit of an electrical machine?
[IAS-1993]
a. Temperature rise of the machine.
b. Type of protection used in the machine
c.  Design parameters of the windings
d. Type of protection used in the machine.

2.  the voltage across the open -circuited field terminals of a synchronous machine under slip test is [IAS-1994]
a. DC
b. Ac of slip frequency
c. a modulated supply frequency ac voltage with slip frequency envelope
d. Ac of supply frequency

3.  In a line printer used to print the output of a computer the paper is required to be advanced by a line spacing as soon as printing of the line is over. which one of the following motors is best suited for this application ?
[IAS-1995]
a. Dc motor
b. Synchronous motor
c. Induction motor
d. Steper motor

4.  Consider the following statements about single phase reluctance motor:
1. The starting torque is a function of rotor position.
2. The torque developed at sub synchronous speeds varies sinusoidally.
3. Starting is asynchronous but running is synchronous.
4. It pulls synchronism on switching on dc excitation.
Of these statements correct : [IAS-1996]
a.1,2&3
b.2,3&4
c.1,3&4
d. 1&4

5. For proper synchronisation of a large synchronous machine to a bus, the frequency of the-incoming machine [IAS-1997]
a. Should be equal to
b. Should be higher than
c. Should be lower than
d. Any value

6. In the slew range of a stepper motor, it [IAS-2001]
a. can start, stop and reverse as desired
b. cannot start but can stop and reverse on command
c. cannot start, stop and reverse on command
d. cannot start and synchronize but can reverse or command