Can anyone help please.

The chief maintenance engineer has asked you to evaluate and compare the advantages and disadvantages of DC and 3-ph AC motors for two electrical installations in a new extension. The applications he wants you to consider for both types of motors are:

a) A motor for 3 storey, 8 passenger lift

b) The operation of fan motors in an air conditioning system

 

1) Use a descriptive subject title other than "Motors". Think of how helpful your title is to readers.

2) This is "Homework Help", not "We do your homework for you". Show your best effort at answering the question.

 

Thanks for the help

 

Thanks for the help

You're welcome.

 

I will wait for someone that knows the answer........

 

A) Hydraulic or cable?

B) Condensor fan motors or air movers?

 

Cable and Condenser.

 

What can a DC motor do that a 3 phase induction motor can't?
For the DC motor, think "electric car" like even the Prius.
For DC, there's the brushless DC motor.

3 phase gives you higher cost with greater ____________.

 

Efficiency

Do I mention VFD's

 

A 3 phase motor is more reliable. No start capacitor, no extra start windings etc. Reliability is only there if 3 phase power is present and you haven't say, lost a phase. I think efficiency may depend on how loaded the motor is.

A VFD is a good option for an air mover in duct work, but probably not for a condenser fan. ECM motors are now common in house furnaces because they can indirectly measure CFM and static pressure.

 

Thanks

 

DC motors have generally been replaced by BLDC PM motors now due to reliability, also VFD's with 3ph motor with encoder feedback have been used in some applications that were typically used for elevator control etc.
Max.

 

Thanks Max