ECN Forum Forums General Topics of the Trade General Discussion Area Wierd things happening....

Feeder for the elevator megged OK, the rattle is being blamed on lack of triplexed conductors. An opinion I could buy into, although does not explain other problems in the building. I have done simular runs (Not triplexed), with simular operating amperages, but have not had a rattle like this. It takes an awfull lot to get (3)250MCM to jump around like this.

Now a question for those motor experts out there. Wye system - Delta connected 6 wire motor - 3 poles on soft start - 3 poles on contactor. This is a configuration that I have not seen before. I figure the motor could be damaged if the soft-start failed, which it has in the past. Anyone with an opinion on this?

Mark,
Join the club there, mate!.
I've never heard of a set-up like that before.
So I understand the motor is being fed with both the soft starter and the contactor?.
Why isn't the soft-starter alone feeding the motor and the motor configured for Delta with links between the terminals?.

It would be simular to this (see link: delta run diagram), but 1,2,3 on soft starter, and 4,5,6 on contactor, they are linked parrallelon the line side of each, comprising Delta[/].
http://www.usmotors.com/Connections/11658.pdf

I had questioned that the motor might be wired wrong, and was meant to be wye start, delta run, or vise-versa, but the equipment is wired according to manufacturers diagram. As what I guess one would call "Accross the line start, but half soft-start, or delta part start"? It doesn't make a whole lot of sense to me.

This is [i]"Elevator equipment", so I really cant mess with it, ie different license, and liability, blah, blah, blah. But it would be interesting to see if this would work better as wye-start/delta-run.

I think this link might be helpful as far as the motor connections to the soft start are concerned. The soft start is connected exactly as you have described.
http://www.elevatordrives.com/resources/hpv100_techmanual_tm5590.pdf

The unit that Bigrockk links to makes perfect sense. You have a thyristor soft start system that reduces the voltage to the motor, backed up with a contactor. The only thing 'strange' about it is that the control circuitry is _inside_ the delta. If either the soft start or the contactor is open circuit, then no current can flow.

I hedge a guess that one of the phases in the motor is reversed, or that a coil or phase group inside the motor is reversed. When a three phase motor is properly connected, you end up with three nodes that can be connected to your three supply leads. Swap any two, and you reverse the motor. But with more than three leads, you can easily reverse _subsets_ of the winding. Most of the motor is pulling in one direction, but parts of the motor are pulling in the opposite direction.

-Jon

Bigrockk, yep thats it! Slightly larger for a 75HP motor. I haven't seen a set up like it before.

Jon, I suspected that at first too, but all of the leads go to the right phases, as they are marked.... I cant ring them out as I technically cant touch the equipment. But I did look! One of the i' ans t's I have crossed and dotted. I still have a few more to cross and dot, like I think the pump valve timing is off, and I really what to see what this beast does to voltage elsewhere in the building, crack open the main and check it too.

I'm one of those types of people that have to put both hands on a problem, not just a finger. There is one or a few things wrong there in that building, and just cant get my mind off them.

Good point Jon (Winnie),
Our motors as they are wound here come out to 6 terminals labelled A1-A2, B1-B2, C1-C2.
A1-A2 constitutes a single winding in a 3-Phase motor, as does B1-B2 and so forth.
You can configure a motor to work in Star or Delta by changing the links within the terminal box or leave the whole thing open with 6 wires fed from a Star-delta Starter.
All of the Star-Delta conversion happens within the Starter itself, with the 3 contactors, 1 Main, 1 Delta and a Star contactor.
There is also (or should be) a timer that changes the Starting Contactor from the Star start to the Delta run mode.

This is probably a silly question but have you been able to load test the motor? I know you can't touch the equipment but I wonder if using a "clamp on" to test current draw is considered acceptable?
As I am sure you know if all three phases are balanced then it would be a pretty good assumption that the connections (internally and externally) are ok.
Is it possible that the soft starter is not adjusted correctly? Maybe adjusting the soft start to ramp up the voltage a little slower will solve some of the problems such as the rattle in the conduit and Hid lights dropping out when the motor starts.
It has to be tough when you can't really lay your hands on the elevator equipment...the temptation to dig in and solve this would be a little nerve racking.

Next time I get access to the equipment I want to get the starter data to compare.

This is the motor data: http://www.markhellerelectric.com/motordata.htm

In-rush is roughly 650+A, with possible larger spikes that I cant see. (About 10 seconds at start, and is the source of the rattle and VD at the disco is 185V from 208V a little too much IMO) operating amperage is roughly 160A - 180A (which I think is high, seeing that the elevator was empty)

I checked VD at start-up of this elevator at my TI panels, which go out of a different section of the same main, and they only drop 1 volt. Not that it doesn't mean there is not other distortions.