Why escalators uses DC motors instead AC ?

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Electric stairs (escalators):

Q.-Why electric stairs or escalators uses DC motors instead AC?

Ans_         DC compound motors are used in elevators. A DC compound motor can be called as a superimposition of DC series and DC shunt motor. So, it has high starting torque like a DC series motor and has better control of speed like a shunt motor. Both these features make it ideal to be used in lifts where the lift needs to break high stall torque and also needs efficient speed control over its operation - be it travelling one floor or 50 floors at a time.

The compound motor responds better to heavy load changes than a shunt motor because of the increased current through the series field coils. This boosts the field strength, providing added torque and speeds.

Thus, DC compound motor satisfies the load and operational requirements to be used in an elevator and is the most sought for.
             



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