Which Motor is Useful in Lift Mechanism?

What's the difference between an elevator and a lift?

The Atlantic Ocean.

Yeabut how come DC motors are suitable for elevators but not for lifts? Guess it's some Ramakrishnan weird.

CR4 doesn't have a Good Question voting button.

Lifts raise and lower petrol and lorries.

Elevators raise and lower gasoline and trucks.

. . . and store grain.

I believe the semantic difference is that "elevators" move people and are subject to much MUCH more stringent requirements with regard to safety and reliability. The term "lift" is more often associated with things like car parking lifts and freight elevators. Yes, I realize I used one term to define the other, but that's just my observation from when I was involved in equipment for the passenger elevator industry.

That said, MANY of the major players in the passenger elevator industry have embarked on using VFDs and induction motors to replace old DC motors now. It's not something that VFD mfrs pursue directly because of liability concerns (here in the US anyway), but they will sell the VFDs to elevator mfrs who take on that risk.

In the UK, the term "lift" is used almost exclusively in either case; if anything, the opposite use of the terms is applied in the applications you describe.

The OP does not reveal their provenance.

Actually, with today's modern electronics and microprocessor control systems, the differences between AC and DC motors is rapidly fading. They are both electromechanical energy conversion devices, and their distinction electrically, ends at the supply terminals.

and your question is?

I was wondering if I missed something. I don't remember seeing a question or question mark, either. -- JHF

It's in the title of the thread.

AH! So it is. He (she) then proceeded to answer his(her) own question?. -- JHF

so it is!! The title is a question

The rest is a statement TELLING us what I should be, why it should be and to my mind show all of CR4 how right you are.

Now if you are convinced that you got it right, why post?

I think the OP was telling what he understood about DC vs induction motors, but wanted confirmation and any other additional alternatives anyone else might have. I had done some elevator code reviews for permitting in the past and know that not only are there many acceptable ways to skin the cat, but also milk the rodent.

None of your drawbacks are real. There are low voltage and high voltage DC motors. Speed regulation changes with application and motor/drive selection. There is no such thing as a zero load condition. Bearing friction and rotor inertia are not zero.

There are two basic types of DC motors: Series and Shunt. Series has a high torque and Shunt has good voltage/speed regulation. A Compound motor blends different degrees of each type into the same motor. You could even have a separate adjustable field for motor control. There's not much difference between some DC motors and a DC generator. I'm sure someone somewhere can even make a custom motor if there's enough demand for it.

Any motor could be used in an elevator or lift application. Due to normal friction in the mechanism, a DC series motor would still be working with a load against it and speed control electronics with feedback loop could provide adjusted voltage, up to and including controlled braking by reversed low voltage. Given the state of controls, I would expect to see a rise in the use of brushless DC or servo type motors in the future.

The difference between motor types is getting pretty thin in some areas, such as synchronous vs brushless DC vs 3 phase. The motor configuration is very similar with the main difference being in the control circuitry and the overcapacity built into the motor to allow under-voltage operation or the capability to be used as a torque motor to apply braking, where the direction of torque can be opposite to the direction of actual rotation.

Any motor/control configuration will still have to go through the necessary testing and certification for applicable local, national and international codes and to obtain local permitting and insurance company acceptance, but it can be done if there is enough benefit to justify the expense.