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Topic Title: OLTC VS AVR
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Created On: 06 January 2014 03:28 AM
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 06 January 2014 03:28 AM
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jackdaniel

Posts: 69
Joined: 29 November 2012

There are two types of voltage fluctuation protection for transformer, each of protection has their own advantages, but my concern on voltage variation, which one should be used when dealing with low fluctuation and high fluctuation?
 07 January 2014 12:50 AM
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JonathanHill

Posts: 225
Joined: 09 September 2002

In my world, OLTCs live on power transformers; AVRs live on alternators.

Please explain your vision in a bit more detail so we can better understand

-------------------------
Jonno
 07 January 2014 01:18 AM
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jackdaniel

Posts: 69
Joined: 29 November 2012

Originally posted by: JonathanHill

In my world, OLTCs live on power transformers; AVRs live on alternators.



Please explain your vision in a bit more detail so we can better understand


There are 4 types of configurations for transformer, HT AVR(seperate), HT build in AVR, OLTC(build in) and LT AVR(seperate), LT AVR is not my concern - disadvantages on HT part and less efficient, the most common configuration is OLTC, but how about HT AVR only without OLTC on the transformer?, my question focus on distribution transformer, but there are few cases where the Unit Transformers were installed with AVR instead of OLTC. I want to know the pro and con between these two protection.
 08 January 2014 09:49 PM
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dlane

Posts: 685
Joined: 28 September 2007

The main difference between an HT AVR and an OLTC is that you will have finer control with an HT AVR as appose to the % tapping steps of an OLTC.

An HT AVR is usually less onerous in terms of maintenance, there is less arcing occurring so oil degradation is less and the mechanisms are simpler and more robust. The control side or the HT AVR is much more complex with a higher level of electronics installed.

The main downside is that as far as I know HT AVRs have a size limitation of a few MVA where as OLTC can be sized all the way up to generator step-up transformers.

A transformer with a built in AVR will have a smaller footprint and cost less than one with a separate AVR.

Kind regards

Donald Lane
IET » Energy » OLTC VS AVR

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