1-PH or 3-PH for elevator??!!

[jrannis]

I did a 22 million dollar house in DC which had a 800 amp 3 phase service. The elevator that went in had commercial guts and a residential car. We ran a 30 a 3 phase circuit and the elevator guy used a 30 amp single pole breaker. ?????? We load tested the elevator under load an it only pulled 10 amps!!!!! We put it on a 20 amp breaker and it has been fine ever since.

Would it really need to be a huge motor? The small ones usually only run a hydraulic pump.

 

[jrannis]

The largest single phase motor I have seen is 7.5 hp. A three phase motor is simpler and has less parts. But you can use a three phase motor with single phase input with a derated VFD.

Dont know if I ever noticed a freq drive in an elevator room.
Usually they are packaged and just have a whip to make up.

 

[micromind]

The relay in question a couple of posts back is commonly called a 'phase failure relay'. I've seen them as an 'ice cube' type, plugged into a socket, or a stand alone device.

They all do the same thing, close a set of contacts if the following conditions are met.
1)All 3 phases are hot, and balanced usually within 4%, though this is sometimes adjustable.
2)The phase to phase voltage is within range. This is usually adjustable, normally a 10% tolerance.
3)Phase sequence (rotation) is correct. This is not adjustable. L1-L2-L3 (clockwise rotation) is always the proper sequence. If the incoming power is counter-clockwise, simply swap 2 leads, just like a motor.

Basically, it's a protection relay designed to keep bad 3PH power from damaging equipment. The socket type costs around $50, I don't know of any 3PH equipment that costs less.