Why do we use blakley units in school laboratorys

[cleatus]

Im currentley working on a school laboratory install and we are using blakley transformers to supply socket outlets, can anybody explain to me why this is.

 

[johnboy6083]

are they isolating transformers? if they are isolating transformers, then they will be used so that the kids cannot get a shock while messing about with bunsen burners, and worscter boards ect

 

[mogga]

Blakley ones are probably just specked as the guy doing speck has been told Thats what we have used in the past

 

[cleatus]

I havent seen them yet but by the sounds of things they have breakers in them. I remember learning something to do with a double wound transformer providing electrical seperation which i didnt really understand. Has this got anything to do with it?

 

[RWJ]

I think they're just the make specified like MK accessories and Crabtree boards?? (why not crabtree accessories) seem to be round here on school jobs.

 

[IQ Electrical]

It'll be a 1-1 transformer with some form of current limiting to restrict leakage.

We did a science classroom last summer and the transformers had integral 5mA RCD's too

 

[Deleted member 9648]

As above...they are a 1 to 1 CT isolating transformer with normally 5ma or less RCD protecting the secondary side.
The CT transformer means that the maximum voltage to earth is 120v,which reduces the shock risk.Remember though that both poles on the secondary side are at 120v to earth so all sockets etc must be DP switched.

 

[i=p/u]

so if they touch doesnt that 120v half 60v on each to earth

 

[davelerave]

sounds like it's 115-0-115


if it's 5mA must be 230v rcbo's


you wouldn't be using rcd+dp mcb's anyhow due to nuisance

 

[IQ Electrical]

sounds like it's 115-0-115


if it's 5mA must be 230v rcbo's


you wouldn't be using rcd+dp mcb's anyhow due to nuisance

They are centre tapped but the rcd relay is a back-stop for the current limiting resistor.

 

[UNG]

I assume it these you are installing

Standard WELU series | Blakley Electrics

The tech data sheet and FAQs can be found here

http://www.blakley.co.uk/sites/default/files/TDS9 - FAQs Safe Supply Units.pdf

Should give you all the information you need cleatus

 

[davelerave]

They are centre tapped but the rcd relay is a back-stop for the current limiting resistor.

ya-i got it now

 

[Knobhead]

Just had a look through the PDF file. Along with them being 115-0-115 there is a 12K NER to restrict fault current even more along with 10mA RCD.
They look good units.

Someone mentioned that they should be DP switched, to my mind they should also be DP fused. What kind of plugs/sockets are you using?

 

[davelerave]

13amp DP switched sockets and mcbs for CTE secondary

2 browns and a cpc for the final circuits probably-same as 110v cte

ordinary testers don't seem to be compatible-rcd and loop-impedance because of resistor

 

[malcolmsanford]

Are any of the little darlings setting up a TV repair business .....................quite often use these type of transformers in laboratories needing a non-conducting location...................get the wood out as well