11Kv/415v Transformer Tap Changers

They should be onload tap changers for the uninterrupted operation. You should do more research it seems.

Thanks, just to clarify my question, I want to know; what is the most common type of 11kv to 415v transformer installed in the UK fitted with, is it:

On Load tap changers?

Off Load tap changers?

The type of tap changer depends on the capacity and application requirements. You can refer the service manual supplied with the transformer for more info.

Welcome to CR4, malby!

Regretfully, I must respectfully disagree with Anonymous Poster #1.

I have been in the electric utility business for over 30 years and have NEVER seen an on-load tap changer (OLTC) on a transformer whose low voltage side is below 3.3 kV, and only rarely at that level. It is simply not worth the expense. Normal practice is to regulate the supply from the source, either with an OLTC on the substation power transformer or with regulators on the distribution feeder. If the distribution transformer is served directly from a generator, the automatic voltage regulator on the generator will maintain the voltage. There is no reason to put 2 regulating devices in series.

Many newer distribution units are equipped with a no-load (or off-load) tap changer (NLTC) on the high voltage side. This is primarily to compensate for supply voltage which is consistently out of tolerance due to feeder loading or line capacitors. Our utility (USA) specifies units above 500 kVA to include a NLTC with taps at +5.0%, +2.5%, 0.0%, -2.5% & -5.0% of nominal voltage.

There is a very good primer on the subject here.

Your correction was helpful. #1

Most 11/.4KV transformers in the UK domestic supply system aren't fitted with tap changes. Whereas on industrial sites they are normally fitted with off load units with a range of -5 -2.5 0 +2.5 +5% as stated by pwr2thepeople. On all the major sites I've worked on voltage regulation has been dealt with at the 33/11KV intake transformers with automatic on load units.

Thanks for that pwr2thepeople it is one of the more concise introductions to transformers i have seen.

That's really helpful Tony, I suspected it may not be economical for these type of transformers, basically my interest in this is for a UK distribution network model I am building, it will include thermal and electrical elements and I was wondering if i could use taps on 11kv to .4kv transformer to control the optimisation of voltage levels....... I am beginning to think not if there aren't any/many, i had heard that it is only considered on this type of transformer if it is rated at 1000kvA.... You don't happen to know what standards the distribution network operators are required to work to by any chance do you?

As to transformers for the local domestic distribution network I think one of the reasons for no external tap changers to be fitted is the problem of vandalism. There may be internal links fitted, safely away from the fools that seem to run wild in this country.

For the standards, have a look on Google.

there are both on/off load tap changer. off load tap changer are very much cheaper than on load tap changer. on load tap changer can be associated with voltage regulation.