C T Ratio

[stretchyboy]

I have quoted for a job of fitting a CT chamber and doing the intake alterations to change a 100A 3-ph supply to 200A 3-ph and in doing so obtained a price for the CT Chamber from Ryefield. The metering company need to know the CT ratio to complete their form so they can book the job, so the client asked me for this info. I got on to Ryefield who said that they dont supply the CT coils ??? and as far as I remember from last time I installed one they came in the chamber already, so now i'm trying to get an answer while Ryefield have finished for the week at 2PM and no-where on-line can I find a decent pdf of the kit to look at ................. help

 

[Darkwood]

As far as i recall a standad meter kw/h requires a a current between 0 to 5A so if you had a 200amp supply i believe you need a ratio of 200/5, the 200 is proportional to your current you are measuring and the 5 is a standard secondary current for the meter.

Thus a 100amp supply would need c.t.s with a 100/5 ratio etc

I think this is how it works when choosing your c.t.s but be best to look up some c.t.s in a catalogue and ring tech for advice which is only the cost of a phonecall, they are always happy to help and this is how i learn alot of things college never taught me.

Note you will probably have to price for a c.t. per phase

 

[stretchyboy]

cheers, that helps, but Ryefield are an old firm that finishes early on a friday and I seem to remember ringing 'during their lunch hour' once too ;-( so their technical probably wont be around until Monday midday after tiffin and jam sandwiches.

 

[Guest123]

Hi.

I use these little fellas meself.

Bullet proof and dead easy to fit.


http://www.crompton-instruments.com/DRK-CT-INSTAL.pdf

 

[Lou7]

I installed a 600A Ryefield ct chamber a little while back, CT's were supplied by the metering co.
Scottish & Southern I believe.

 

[jams88]

Please be aware you need to specify metering CTs as these are different from protection CTS , also the supply authority will require a certain class of CT ( 0.5M) ( 0.1M) etc

 

[Darkwood]

Please be aware you need to specify metering CTs as these are different from protection CTS , also the supply authority will require a certain class of CT ( 0.5M) ( 0.1M) etc

I do hope he's sorted this out by now as its nearly 4 yrs old since this thread was posted but you could be lucky as he might still be waiting in a queue for technical support......... You are no3 in the queue ....we will be with you shortly!

 

[CSEE]

It will be a 200/5 ratio CT. I have just done this works with a 800A upgrade

 

[Knobhead]

It will be a 200/5 ratio CT. I have just done this works with a 800A upgrade

As per usual outdated news arrives 6 years late.

 

[brookster]

Necro thread -

just remember and short them out if you cannot connect em up