Two phase elevator motor on a three phase service

[Phil Corso]

Conmgt...

Using off-the-shelf single-phase xfmrs, having the right combination of taps, will cost apprx

o 2 x 10kVA Xfmrs, $2.4k.

o 2 x 7.5kVA Xfmrs, $1.8k

Above is based on xfmrs having sufficient tap values. If taps are not sufficient, then an additional boost-buck xfmr is required, costing apprx $250. I have not included sales tax. I figure if it's a go, you can handle purchase matters, right?

Will reveal electrical details as soon as they become available to me!

Phil

 

[Phil Corso]

Conmgt....
Is the motor an Open, Drip Proof design? And, is the motor manufacturer "Western Electric?"
(Just a trip down memory lane!)
Phil

 

[T.M.Haja Sahib]

Replacing the motor is certainly an option but not so simple. I'd need a 15hp 980rpm motor or motor/gearbox. The motor and traction sheave are in a very small mechanical room on the roof. Access to the roof is via an extension ladder or small roof hatch. A 15hp motor isn't something I can carry on my shoulder so a crane would be needed.

Then there?s the 100y.o. motor control. The control panel for the existing motor, as I mention previously, is as old as the motor...100+/- years. Will it work with a new 3ph motor? Will a code require that it gets updated?

The existing motor has a unique shaft and bolts directly to the brake. The traction gearbox bolts directly to the other side of the brake. There is no isolation coupling between the two, things have to line up perfectly and custom machined parts will certainly be needed.

A transformer on the other hand can be installed at the service panel and conductors sent up the existing conduit to the motor room.

I have a call into a local elevator shop to get their opinion and answer questions about the control panel.

So you don't want any lift modernization and savings associated with it?

 

[zbang]

So you don't want any lift modernization and savings associated with it?

Any energy savings could easily be eaten up by the installation cost, and if the owner doesn't want to "modernize", then it's not going to happen unless ordered by the city/state.

 

[Phil Corso]

ConMgt?
Here is my suggestion for a ?Plan?:
1) Procure two (2) 4-winding transformers having: 10kVA capacity each; 240x480V primary; 120/240 secondary; fitted with 2, 2?%, AFNC Taps, and 2 or 4, 2?%, BFNC taps in the primary winding.
2) Here?s the kicker! Install the transformer so that the low-side, 120/240V, windings are connected to the 208V, 3-Ph source, and the high-side, 240x480, windings are connected the 2-Ph load (isolated phases).
3) One xfmr, called the ?Main-Winding? when connected as the horizontal-leg of a T-assembly, will produce an output of 218V.
4) The other xfmr, called the ?Teaser-Winding? when connected as the vertical-leg of a T-assembly, will produce an output of only 189V! This is due to the fact that some Sqrt(3)/2, or only about 86.6% of the input, is impressed across the Teaser-winding.
5) To compensate for the deficiency noted in 4) procure a Boost-Buck xfmr! Line-to-Load ratio must be 240/208, and its capacity about 11-12kVAl
ConMgt, I don?t know how much detail you want to present publically on the forum. So I suggest you contact me directly for Part Numbers, vendors, tech contacts, and drawings. Then, if you decide it?s OK, the info can be presented on the forum.
One last thought, if the Elevator-Panel load is significant, i.e. say > 100Watt, then xfmr capacities must be altered.
Regards, Phil Corso

 

[Phil Corso]

ConMgt...

Penultimate sentance should have read.. "may have to be altered"!

Phil

 

[T.M.Haja Sahib]

Any energy savings could easily be eaten up by the installation cost, and if the owner doesn't want to "modernize", then it's not going to happen unless ordered by the city/state.

Installation cost is one time but energy loss cost is recurring. If VVVF drive could be used to control the two phase elevator motor without any intervening transformers it could result in considerable energy savings but I think the VVVF drive need be custom built.

 

[kwired]

Installation cost is one time but energy loss cost is recurring. If VVVF drive could be used to control the two phase elevator motor without any intervening transformers it could result in considerable energy savings but I think the VVVF drive need be custom built.

And if energy savings does not recover cost of installation in a certain time period it is just not a wise investment.

 

[T.M.Haja Sahib]

And if energy savings does not recover cost of installation in a certain time period it is just not a wise investment.

So it requires an exercise in Engineering Economics. A. VVVF drive is the first step in introduction of modern trends in elevator technology. in this age old installation and cost effective solution to the OP's problem IMO.

 

[kwired]

So it requires an exercise in Engineering Economics. A. VVVF drive is the first step in introduction of modern trends in elevator technology. in this age old installation and cost effective solution to the OP's problem IMO.

My statement was a general statement about replacing products with energy efficient products. Initial cost and payback from savings are important factors in considering if it is a wise investment. For the elevator - I know little about elevators, and owner of the building probably doesn't know much technical information either. Owner will want to know what cost is, what expected payback is and only the owner knows if he thinks it is a good investment, or if he trusts the person trying to convince him it is necessary. Maybe there is plans to put in a new elevator in the future, or to sell the building. Long term investments may not be that important in those cases.

 

[iwire]

templdl, I started this post to have a conversation with other members to learn something not hear something. Since this appears to be a field that you work in, it's a very short conversation for you. But to me, and I'm sure many many other watchers, 3ph to 2ph is new and intriguing and this is a long conversation because I'm a curious person. I've learned a lot. Care to follow Phil and Joe's lead and contribute and enlighten?

Replacing the motor is certainly an option but not so simple. I'd need a 15hp 980rpm motor or motor/gearbox. The motor and traction sheave are in a very small mechanical room on the roof. Access to the roof is via an extension ladder or small roof hatch. A 15hp motor isn't something I can carry on my shoulder so a crane would be needed.

Then there?s the 100y.o. motor control. The control panel for the existing motor, as I mention previously, is as old as the motor...100+/- years. Will it work with a new 3ph motor? Will a code require that it gets updated?

The existing motor has a unique shaft and bolts directly to the brake. The traction gearbox bolts directly to the other side of the brake. There is no isolation coupling between the two, things have to line up perfectly and custom machined parts will certainly be needed.

A transformer on the other hand can be installed at the service panel and conductors sent up the existing conduit to the motor room.

I have a call into a local elevator shop to get their opinion and answer questions about the control panel.

For what it is worth in most areas 'electricians' cannot touch anything to do with an elevator beyond the NEC required disconnecting means.

We could not even consider changing motors, control boards or adding a VFD. All those items would have to be handled by an elevator contractor and typically would be extremely costly meaning it would be less costly to do whatever it takes on the supply side even at the sake of electrical efficiency.

 

[conmgt]

As far as efficiency is concerned, are we talking about transformer losses or motor efficiency?

This elevator is a freight elevator which I'm sure was used heavily in it's heyday when the building was making sandpaper and grinding wheels (Norton Abrasives) but now it's artist's lofts and is used once a week maximum to travel 40' up/down. To me, it sounds like replacing the motor for efficiency sake would have quite a long payback.

How many kW/h would the transformer consume?

 

[conmgt]

ConMgt?
Here is my suggestion for a ?Plan?:
1) Procure two (2) 4-winding transformers having: 10kVA capacity each; 240x480V primary; 120/240 secondary; fitted with 2, 2?%, AFNC Taps, and 2 or 4, 2?%, BFNC taps in the primary winding.
2) Here?s the kicker! Install the transformer so that the low-side, 120/240V, windings are connected to the 208V, 3-Ph source, and the high-side, 240x480, windings are connected the 2-Ph load (isolated phases).
3) One xfmr, called the ?Main-Winding? when connected as the horizontal-leg of a T-assembly, will produce an output of 218V.
4) The other xfmr, called the ?Teaser-Winding? when connected as the vertical-leg of a T-assembly, will produce an output of only 189V! This is due to the fact that some Sqrt(3)/2, or only about 86.6% of the input, is impressed across the Teaser-winding.
5) To compensate for the deficiency noted in 4) procure a Boost-Buck xfmr! Line-to-Load ratio must be 240/208, and its capacity about 11-12kVAl
ConMgt, I don?t know how much detail you want to present publically on the forum. So I suggest you contact me directly for Part Numbers, vendors, tech contacts, and drawings. Then, if you decide it?s OK, the info can be presented on the forum.
One last thought, if the Elevator-Panel load is significant, i.e. say > 100Watt, then xfmr capacities must be altered.
Regards, Phil Corso

I have personally have no issues presenting anything publically and I think the rest of the viewers would find it interesting, as do I. Are there any reasons why I wouldn't want anything to be seen publically.

The only other load would be the light in the car...100W or so and I'm not sure where that's connected.

 

[Phil Corso]

ConMgt... The the three transformers in mibd are Acme Electric Co:

o P/N T-2-53516-3S, for the two, 10-kVA4, 4-winding, transformers.

o P/N T-1-13074, for the single, Boosty-Buck transformer,

The tecnical contact is Bruce Barnes @ 800-334-5214!

If you want to purchase them new, they will GIVE YOU THE NAME OF seyou of the closest rrep in your area.
Yo canalso check with other distribvutors, for the exaxt model, or those form other vendors having like-specificaTIOS


o
10.- kVA sise

 

[Phil Corso]

ConMgt... edit timer ran out before I completed my post.

o If 5% taps are available, then B-B is unnecessary, but I did not fully investigate that possibility.

o Also check E-bay for used Xfmrs.

Regards, Phi Corso

 

[kwired]

As far as efficiency is concerned, are we talking about transformer losses or motor efficiency?

This elevator is a freight elevator which I'm sure was used heavily in it's heyday when the building was making sandpaper and grinding wheels (Norton Abrasives) but now it's artist's lofts and is used once a week maximum to travel 40' up/down. To me, it sounds like replacing the motor for efficiency sake would have quite a long payback.

How many kW/h would the transformer consume?

Is it still a freight elevator? Passenger elevators have much more regulation than freight elevators and like has been said you usually must be properly licensed to even look at one if you are anything besides a passenger.

If it is not used that much motor efficiency will not be a very big impact on energy bills if replaced with something more efficient. A transformer that is inefficient that is energized 24/7 can waste a fair amount of energy, and will actually be more efficient if loaded than if idle. I suppose you could make it so the transformer is de-energized while not in use with some extra controls if you want it to be automatic. This assumes your motor is the only two phase load and controls are derived from a separate source that will remain energized.

 

[T.M.Haja Sahib]

....it sounds like replacing the motor for efficiency sake would have quite a long payback.

Is it possible to replace existing elevator controls with modern ones as a first step? If yes, it may lead to better quality of service, providing more value to customers and energy efficiency too.

 

[zbang]

Is it possible to replace existing elevator controls with modern ones as a first step? If yes, it may lead to better quality of service, providing more value to customers and energy efficiency too.

Possible? Of course. Cost-effective? Not likely, for all the reasons previously stated. (You might want to research the concept of "cost of money" as it relates to cost-recovery over time.) Also, value is only what's valuable to the customer, if they're not concerned about the old freight elevator, it'll be hard to get them interested.

If you search back in the forum, I think you'll find at least one case where installing a whole-building Scott-T transformer was a good deal cheaper than replacing the existing 2-phase service with 3-phase. (IIRC, the building was being rewired as 3-phase and the PECO service was 2.)

 

[templdl]

Possible? Of course. Cost-effective? Not likely, for all the reasons previously stated. (You might want to research the concept of "cost of money" as it relates to cost-recovery over time.) Also, value is only what's valuable to the customer, if they're not concerned about the old freight elevator, it'll be hard to get them interested.

If you search back in the forum, I think you'll find at least one case where installing a whole-building Scott-T transformer was a good deal cheaper than replacing the existing 2-phase service with 3-phase. (IIRC, the building was being rewired as 3-phase and the PECO service was 2.)

I looks as if we've about come full circle now. You're spot on hitting the nail right on the head as my point was in my post #35.
I must say that I have been quite intrigued by the potential solutions to the 3ph to 2 ph issue. With this litigious society that we have today I also wonder about the risk verses reward in using the Rube Goldberg approach to this issue.
As I recall when I was a sales engineer for a dry type distribution transformer manufacturer a 3ph-2ph transformer adder was 25% over a standard 3ph transformer. With all of the time spent so far beating this issue up a 3ph-2ph transformer could have been ordered, paid for, and on sight by now.

 

[T.M.Haja Sahib]

Periodic changes to the ASME A17.1/CSA B44-07 Safety Code for Elevators and Escalators have brought about new requirements for elevators and escalators to improve and enhance the safety and accessibility of these systems. I do not know how much of this code is applicable to the old freight elevator under discussion here, if any people also regularly ride in it along with freight.