1. The ordinary dc machines are not favourable as amplidynes due to _________
a) sluggish transient response
b) low stability
c) poor gain
d) high steady state error
Explanation: The sluggish transient response of the ordinary dc machines makes them inappropriate to use them in amplidynes
2. In rotating amplifiers, armature reaction mmf of the first stage is made to act as field flux for second stage.
a) True
b) False
Explanation: Yes, the reaction mmf of the first stage is made to act as field flux for second stage to have faster transient response
3. The cross field machines have _________
a) two fluxes electrically in quadrature
b) two fluxes mechanically in quadrature
c) one set of brushes per pole
d) all of the mentioned
Explanation: The cross field machines have two fluxes electrically in quadrature.
4. In cross field rotating amplifiers, there is _________
a) two stage of flux generators
b) three stage of flux generators
c) four stage of flux generators
d) eight stage of flux generators
Explanation: There are two stages for flux generators in order to have faster response in the system
5. Metadyne is _________ feedback with respect to main ___________
a) negative, current
b) negative, voltage
c) positive, current
d) positive, voltage
Explanation: Metadyne is negative feedback with respect to main current flowing in the second stage set of motors.
6. An amplidyne, d-axis flux is always neutralized due to _________
a) compensating winding at all possible loads
b) interpoles at all specified loading
c) feedback at all possible loads
d) feedback at fixed loading
Explanation: The d-flux is neutralized by compensating winding at all possible loads as the same flux will be produced but in the opposite direction so as to cancel the flux.
7. In amplidynes, the resultant d-axis flux is _________
a) field flux
b) difference of field flux and main flux
c) sum of field flux and main flux
d) cross magnetizing flux
Explanation: The resultant d-axis flux lies along the main field poles and are so field flux. The d- axis is completely under the control of field winding and is unaffected by direct axis current.
8. Amplidynes are best applicable in _________
a) feedback control systems with regulated power supply.
b) power supply
c) speed control of large motors
d) All of the mentioned
Explanation: Amplidynes find applications in feedback systems with large power handling requirements.
9. Interpoles provide mmf more than armature mmf in a dc machine.
a) True
b) False
Explanation: Interpoles nullify armature cross magnetizing flux and the reactance voltage. So it is more than the armature mmf for a good efficient machine.
10. The delay of the commutation occurs due base cause of emf induced due to _________
a) self inductance, mutual inductance
b) self inductance
c) mutual inductance
d) leakage inductance
Explanation: The commutation in dc machines is delayed because of the emf induced in the coils and the mutual interaction of the field with neighbour coils.