No secondary over current protection?

[iwire]

I think there is some confusion, maybe based on typical usage for people who perform their work differently (not wrong) than others may perform their work. "there is more than one way to skin a cat", sort of statement.

I understand but that is not all that he is saying.

He seems to be saying UL requires X4 to be bonded to ground, I see no such requirment,

 

[tryinghard]

Not what I said. Again, show me the ground in the diagram.

You can have a transformer with a terminal tied to the transformer housing. That is not what iwire has in his picture.

I answerd this at Post #86, I'm simply making a point about the label.

 

[tryinghard]

Show me anything at all that indicates grounding X4 is part of or required by the listing.

Does the fact that it is noted on the equipment label qualify this?

 

[iwire]

Where is iwire's transformer not being used as listed?

Just to be clear, neither I, nor the comapny I work for had anything at all to do with the selection or installation of this unit. We just have to service the unit it supplies.

 

[iwire]

Does the fact that it is noted on the equipment label qualify this?

Where do you see this note?

 

[mivey]

I answerd this at Post #86, I'm simply making a point about the label.

That's no answer.

The label also shows seven different tap voltages. Is he required to use all of them?

 

[tryinghard]

Again it lists 120v at the secondary and the secondary delta includes the X4, there is no other purpose for X4 whatsoever.

 

[mivey]

Again it lists 120v at the secondary and the secondary delta includes the X4, there is no other purpose for X4 whatsoever.

Still not getting how that says you must ground X4.

It appears you are mis-interpreting what the label is telling you.

 

[mivey]

Still not getting how that says you must ground X4.

It appears you are mis-interpreting what the label is telling you.

This would show the center tap having to be grounded:

 

[tryinghard]

This would show the center tap having to be grounded:

Sure does, again the fact the X4 is only for grounding that fact coupled with the noting of the 120v on the secondary qualifies this to me.

 

[tryinghard]

This particular transformer can be grounded I am arguing whether it?s required by labeling/listing. I believe this transformer requires grounding because two of the phase conductors can have 120v to ground. I my travels I work with 240 deltas often and I have never used this type transformer on an ungrounded system that I can remember anyway. This doesn?t mean much accept to say do whatever you want, I just see it on the label and if you see this as optional; cool your good to go man.

 

[mivey]

...I believe this transformer requires grounding because two of the phase conductors can have 120v to ground...

Iwire's label does not indicate, or say "to ground" anywhere.

 

[M. D.]

I found this ,.. I don't think it is required... I think it is a selling feature,... if a small amount of 120 is required this transformer can provide it ,.. it does not have to .

Here is where it came from
http://www.geindustrial.com/catalog/buylog/08_BL.pdf

Product Description
GE Type QL midtapped transformer enables the user to transform
three-phase power from 480 Volts primary to 240 Volts second-
ary and have 120 Volt, reduced capacity tap (RCT) single-phase
capability as well. This is because a single-phase midtap is
broughtout of one coil of the unit’s three-phase secondary wind-
ing. These transformers are UL listed, File E-79145.

Application

The Type QL midtapped design can be used wherever there is 480
Volt, three-phase supply available and the load is primarily 240
Volt three-phase with a nominal amount of 120 Volt, single-phase
power required. Normally, in this instance, a small single-phase
as well as a three-phase transformer would be required to
provide the necessary transformation.

Caution:
When utilizing the 120 Volt midtap for single-phase
applications, the single-phase load should not exceed 5 percent
of the three-phase kVA rating. The three-phase kVA load must be
reduced by the same percentage as that added by the single-
phase load. Additional loading beyond 5 percent may cause the
transformer to overheat and fail. If the single-phase load is in
excess of 5 percent, itis recommended that a separate single-
phase unit be used to handle the load.
Type QL Midtapped Transformer

 

[www.assuredelectric.net]

#8's and the unfused 60amp disconnect are definently a code violation.

 

[mivey]

I found this ,.. I don't think it is required... I think it is a selling feature,... if a small amount of 120 is required this transformer can provide it ,.. it does not have to .

Here is where it came from
http://www.geindustrial.com/catalog/buylog/08_BL.pdf

Agreed.

While it would be a little off the beaten path, I could ground X1 and have 120 volt loads connected X1-X4 if I did not have enough 120 volt loads to try to balance the neutral load.

 

[iwire]

While it would be a little off the beaten path, I could ground X1 and have 120 volt loads connected X1-X4 if I did not have enough 120 volt loads to try to balance the neutral load.

I was figuring I could also ground X1 or 2 or 3 and use this to supply corner grounded delta leaving XO unused.

 

[mivey]

I was figuring I could also ground X1 or 2 or 3 and use this to supply corner grounded delta leaving XO unused.

I would figure the same. I would probably ground X1 or X3 even though I would think the X4 to tank insulation would be fine for 208 volts (nothing on the diagram seems to indicate otherwise).

If I grounded X2, I would probably give it more thought. I think if it were restricted, there would be a grounding symbol on the diagram with a dashed line but I can't recall off the top of my head.

 

[don_resqcapt19]

Where in the NEC is there permission to supply equipment without OCPD and use a ground fault alarm?

The ground fault alarm would be required if X4 is not connected. That has nothing to do with the overcurrent protection. It is my opinion that with X4 not used or connected that this transformer is a delta to delta transformer and the primary OCPD is permitted to protect the wiring and equipment on the secondary side of the transformer. 240.21(C)(1)

 

[tryinghard]

I found this ,.. I don't think it is required... I think it is a selling feature,... if a small amount of 120 is required this transformer can provide it ,.. it does not have to .

Here is where it came from
http://www.geindustrial.com/catalog/buylog/08_BL.pdf

The 120v load up to 5% is normal on a delta as far as I know. In other words if more than 5% is needed the overall kva would need to be increased (a 15kva with 800va of 120v load requires a larger transformer like 22.5+)

 

[mivey]

The 120v load up to 5% is normal on a delta as far as I know. In other words if more than 5% is needed the overall kva would need to be increased (a 15kva with 800va of 120v load requires a larger transformer like 22.5+)

And the 3-phase load decreased. From the link:

Caution: When utilizing the 120 Volt midtap for single-phase applications, the single-phase load should not exceed 5 percent of the three-phase kVA rating. The three-phase kVA load must be reduced by the same percentage as that added by the singlephase load. Additional loading beyond 5 percent may cause the transformer to overheat and fail. If the single-phase load is in excess of 5 percent, it is recommended that a separate singlephase unit be used to handle the load.