Isolation Transformer

[Sajid khan]

I Just want to know that, Do we need isolation transformer for Computer loads and its associated Data/server racks.
My previous experience say no we don't need it for computer load.
I am on a hospital project where we are proposing Isolation transformer for ICU, ORs and medical equipment but my peer reviewer is of the view that we need isolation transformer for Data/computers load also.

Any help in this regard is highly appreciated



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[Besoeker3]

I Just want to know that, Do we need isolation transformer for Computer loads and its associated Data/server racks.
My previous experience say no we don't need it for computer load.
I am on a hospital project where we are proposing Isolation transformer for ICU, ORs and medical equipment but my peer reviewer is of the view that we need isolation transformer for Data/computers load also.

Any help in this regard is highly appreciated



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I've not come across one required for that application. And I don't see why one would.

 

[petersonra]

There could be a good reason to do it, but it is not a code requirement.

 

[Besoeker3]

There could be a good reason to do it, but it is not a code requirement.

Not sure that the NEC applies where Sajid is from..........

 

[Hv&Lv]

I Just want to know that, Do we need isolation transformer for Computer loads and its associated Data/server racks.
My previous experience say no we don't need it for computer load.
I am on a hospital project where we are proposing Isolation transformer for ICU, ORs and medical equipment but my peer reviewer is of the view that we need isolation transformer for Data/computers load also.

Any help in this regard is highly appreciated



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Questions...
How stable and predictable is your power source and the associated grounding and bonding practices?
do you have surges or spikes that would cause the data center to be damaged?
why are you doing it for the other equipment?
Using UPS? Will the associated harmonics going back to the mains be a problem?

 

[Sajid khan]

Not sure that the NEC applies where Sajid is from..........

NEC is not applied here but i need a general openion


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[Sajid khan]

Questions...
How stable and predictable is your power source and the associated grounding and bonding practices?
do you have surges or spikes that would cause the data center to be damaged?
why are you doing it for the other equipment?
Using UPS? Will the associated harmonics going back to the mains be a problem?

Power source is not much stable as we have backup generators
Yes we have a problem of surges and spikes during lightning and switching on and off of mechanical equipments
Other equipment comprise of ORs and ICus equipment which are sensitive to harmonics and isolation transformers usually required for such applications
Yes UPS harmonics in the mains is a problem..


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[Hv&Lv]

Power source is not much stable as we have backup generators
Yes we have a problem of surges and spikes during lightning and switching on and off of mechanical equipments
Other equipment comprise of ORs and ICus equipment which are sensitive to harmonics and isolation transformers usually required for such applications
Yes UPS harmonics in the mains is a problem..


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That kind of answers your question.
I would definitely put the isolation transformer in.

 

[dkidd]

I think that harmonic mitigating transformers would be a more appropriate choice.

https://www.hammondpowersolutions.com/en/products/harmonic-mitigating-transformer

 

[Besoeker3]

That kind of answers your question.
I would definitely put the isolation transformer in.

An isolation transformer is not a fix for those issues.

 

[gar]

191010-1101 EDT

What is an isolation transformer? That needs to be defined.

I would not classify an ordinary transformer as an isolation transformer. It does provide DC isolation, and it does more or less remove common mode noise, but does not remove normal mode noise. See
https://micro.rohm.com/en/techweb/knowledge/emc/s-emc/01-s-emc/6899
Nor does an ordinary transformer prevent capacitive coupling from primary to secondary.

Generally I would expect the definition of an isolation transformer as having an electrostatic shield added to an ordinary transformer.

Will an isolation transformer solve all the different problems Sajid has? No.

So the real question is what are the real problems?

Short time voltage drop out, a few cycles, could be very important. This will require a motor generator with lots of inertia, or an electronic UPS.

High voltage spikes can probably be reduced with voltage clampers (MOVs and other devices).

High frequency noise will require filters.

Internal problems like differential ground path noise require some sort of isolation, or using differential signaling circuits.

.

 

[Besoeker3]

191010-1101 EDT

What is an isolation transformer? That needs to be defined.

Um......one where the primary and secondary are not electrically connected?

 

[Sajid khan]

191010-1101 EDT

What is an isolation transformer? That needs to be defined.

I would not classify an ordinary transformer as an isolation transformer. It does provide DC isolation, and it does more or less remove common mode noise, but does not remove normal mode noise. See
https://micro.rohm.com/en/techweb/knowledge/emc/s-emc/01-s-emc/6899
Nor does an ordinary transformer prevent capacitive coupling from primary to secondary.

Generally I would expect the definition of an isolation transformer as having an electrostatic shield added to an ordinary transformer.

Will an isolation transformer solve all the different problems Sajid has? No.

So the real question is what are the real problems?

Short time voltage drop out, a few cycles, could be very important. This will require a motor generator with lots of inertia, or an electronic UPS.

High voltage spikes can probably be reduced with voltage clampers (MOVs and other devices).

High frequency noise will require filters.

Internal problems like differential ground path noise require some sort of isolation, or using differential signaling circuits.

.

Yes By isolation transformer i mean the transformer with electrostatic shielding that will be used to suppress harmonics.



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[Besoeker3]

Yes By isolation transformer i mean the transformer with electrostatic shielding that will be used to suppress harmonics.



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It won't suppress harmonics.
You need a filter for that.

 

[Hv&Lv]

An isolation transformer is not a fix for those issues.

http://www.isca.in/IJES/Archive/v6/i9/5.ISCA-RJEngS-2017-053.pdf

 

[Russs57]

Sounds like you need a true on-line UPS. Given that you have generators that implies you will have an ATS. Typically it is more economical to run 3 phase 480 and have a transformer near/in the UPS to get the 3 phase 208 (or whatever you use in your area).

I have been involved with hospitals for 40+ years now and it is a sad fact that Data/I.T. gets a more robust electrical system.

 

[gar]

191010-2100 EDT

Besoeker3:

The word transformer without any modifier usually means a transformer with multiple separate windings that are not conductively connected internally in the transformer, and/or share the same current paths.

When a modifier is added to transformer, then it implies something is different. So we have as examples auto-transformers, constant voltage transformers, RF transformers, and the isolation transformer.

If the primary voltage has harmonic content, then the electrostatic shield of an isolation transformer will have no effect on that harmonic content. Filtering is required.

.

 

[topgone]

191010-2100 EDT

Besoeker3:

The word transformer without any modifier usually means a transformer with multiple separate windings that are not conductively connected internally in the transformer, and/or share the same current paths.

When a modifier is added to transformer, then it implies something is different. So we have as examples auto-transformers, constant voltage transformers, RF transformers, and the isolation transformer.

If the primary voltage has harmonic content, then the electrostatic shield of an isolation transformer will have no effect on that harmonic content. Filtering is required.

.

Agree. Define your problems and then look for solutions. Perhaps, the guy may have been given a clue on how somebody did solve his own problem! But unique problems need unique solutions, IMO.

 

[Besoeker3]

http://www.isca.in/IJES/Archive/v6/i9/5.ISCA-RJEngS-2017-053.pdf

From the paper:

"It decreases current waveform distortion and improves power factor."

That's just wrong.
As I, and others here have noted, it will not mitigate harmonics.

 

[Hv&Lv]

From the paper:

"It decreases current waveform distortion and improves power factor."

That's just wrong.
As I, and others here have noted, it will not mitigate harmonics.

http://www.apqpower.com/assets/files/AReviewOfHarmMitigTech.pdf

I’ve never used this for this application. I have read several papers on it and have seen some put in installations that use them for this purpose.

i will assume every paper I have ever read on this subject is wrong then...