Correct Answer - Option 3 : Lifts and City electrical trains
Concept:
- Three-Phase induction motors are used more in industrial applications including like compressors, pumps, conveyor systems, textile mills, flour mills and pumping stations and lifting gear.
- DC series motors are used in automotive, hoists, lifts and cranes.
Explanation:
DC series motors have high starting torque and hence they used in lifts and electrical trains. It has to start with high acceleration.
Applications of different DC motors are given below.
DC Series wound motor:
- It has a very high starting torque.
- Hence it is used for heavy-duty applications such as electric railways, mine hoists, continuous conveyors cranes, rolling mills, metallurgical works, etc.
DC Shunt-wound motor:
- This is an almost constant speed motor and its torque varies nearly as the current.
- Hence, it is used for driving constant speed line shafts, lathes, constant speed head centrifugal pumps, fans, woodworking machines, reciprocating pumps, laundry washing machines, milling machines, grinders, small printing presses, paper making machines, metal cutting machines, etc.
DC Cumulative compound motor:
- It has high starting torque and has varying speed within limits i.e. it has self-adjustable speed with changing the load.
- Hence, it is used for driving compressors, pressure blowers, door lifts, circular saws, passenger elevators, freight elevators, etc.
DC Differentially compound motor:
It has low starting torque and has a constant speed, but the dangerously high speed at no load under the circumstances it is seldom used.
