Transformer rating?

[Suyash599]

Sorry if this is a stupid question but- Does 300 in this image below mean 300 kVA?

 

[Besoeker3]

I can't quite read the text but it looks like it could be that sort of size.

 

[winnie]

There should be a detailed nameplate somewhere on the transformer.

I notice lots of transformers that have an easy to read large number on them which is _probably_ the kVA value, but I don't think there is a standard that describes this usage; rather this is something in addition to the proper nameplate.

That 300 is this sort of easy to read from a distance label which probably means 300kVA, but could also be something else such as a street address.

-Jon

 

[pv_n00b]

You could have just got lucky and are looking at transformer #300 in the system. Most of the transformers I look at have no usable data on the outside about the transformer other than some build numbers and the utility ID numbers. Check with the utility to make sure.

 

[PWDickerson]

All the utility transformers in my area have the kVA rating painted in large numbers on the exterior. No stickers though.

 

[paulengr]

That’s a pad mount style transformer. The actual name plate is on the inside of the low side door on the right. It is not on the outside. If you are doing transformer calculations you also need %Z and the winding data and weights so might as well get the door information. Usually the tap changer and oil drain/sample port and all the gauges will be right there too. Once in a while I have found the oil sample port on the left side (high side).

The problem generally is access. On pad mounts owned by the utility they will often padlock it. Once past that the door bolt is often a 13/16” pentagon bolt head (utility socket). If you don’t have one you can often beat a 3/4” 12 point socket onto it. It is shocking how many utilities and plant maintenance groups that own these transformers don’t have utility sockets. Since it’s all low voltage though often the entire cabinet will be open with no divider between high and low.

 

[ggunn]

That’s a pad mount style transformer. The actual name plate is on the inside of the low side door on the right. It is not on the outside. I

Around here the kVA rating of the utility transformer is usually stenciled on the xfmr enclosure. If it is pole mounted the markings are usually large enough to be readable from the ground.

 

[paulengr]

Around here the kVA rating of the utility transformer is usually stenciled on the xfmr enclosure. If it is pole mounted the markings are usually large enough to be readable from the ground.

Most of the time that is true but not always, and paint fades. Duke and Dominion like to assume their electronic inventories are up to date but that’s not always the case.

 

[winnie]

Just around the corner from me there is a bank of 3 pole pigs, in what is clearly a wye configuration, one larger than the others.

The two smaller ones are stenciled '25'. The larger one says '25+'. It is plausible that this is a 75kVA bank.

But as a cautionary message, just below these transformers are a couple of lights, sodium or mercury vapor, not LED. On each light is a label (stickers, not stenciled ) that also says '25', and they look way too small to be 25kW lights.

Jon

 

[electrofelon]

I'd say it's 99.5% chance it's a 300 KVA transformer.

 

[Hv&Lv]

That’s a pad mount style transformer. The actual name plate is on the inside of the low side door on the right. It is not on the outside. If you are doing transformer calculations you also need %Z and the winding data and weights so might as well get the door information. Usually the tap changer and oil drain/sample port and all the gauges will be right there too. Once in a while I have found the oil sample port on the left side (high side).

The problem generally is access. On pad mounts owned by the utility they will often padlock it. Once past that the door bolt is often a 13/16” pentagon bolt head (utility socket). If you don’t have one you can often beat a 3/4” 12 point socket onto it. It is shocking how many utilities and plant maintenance groups that own these transformers don’t have utility sockets. Since it’s all low voltage though often the entire cabinet will be open with no divider between high and low.

Lots of them are on the outside also
Thats been a thing with some manufacturers for the last 10 years or so

 

[pv_n00b]

It all depends on the utility. In PG&E land the rating is almost never on the transformer. With SMUD and other municipal utilities, the rating is usually on the transformer. But in addition to the rating, I usually need the X/R and %Z which are even less likely to be on the transformer.