Show More Ask Question

1 Answer

Answer :

Dynamic or rheostatic braking,plugging and regenerative braking

Like 0 like
Next Page →

Related

Answer : Dc machine is classified as   self excited  separately excited  permanent magnet  Self excited Dc motor is further classified as  series ... are classified as  long shunt short shunt

Description : Regenerative braking (A) Can be used for stopping a motor. (B) Cannot be easily applied to DC series motors. (C) Can be easily applied to DC shunt motors (D) Cannot be used when motor load has overhauling characteristics.

Answer : Ans: B Because reversal of Ia would also mean reversal of field and hence of Eb

Description : A DC chopper is used for regenerative braking of a separately excited DC motor. The DC supply voltage is 400V. The armature current during regenerative braking is kept constant at 300 A with negligible ripple. For a duty cycle of 60% ... to the DC supply is  (a) 78 kW (b) 58 kW (c) 38 kW (d) 48 kW

Answer : A DC chopper is used for regenerative braking of a separately excited DC motor. The DC supply voltage is 400V. The armature current during regenerative braking is kept constant at 300 A with negligible ripple. For a duty cycle of 60% the power return to the DC supply is  48 kW

Description : Which loss has least proportion in DC machines?  (A) Armature copper loss (B) Field copper loss (C) Magnetic loss (D) Mechanical loss