r1 and r2 temperature calculations

[maddfridge]

Hi all

just been going through max zs etc and all the temperature changes


if i have got this right when you measure for R1 and R2 you take the temperature at the time. Apply a rating factor to get it ot 20 degrees and then when calculating zs or what ever to get to 70 degrees multiply it by 1.2 ?

I think simply this is to ensure thermal constraints are being met

ideas please

doin me ead in need another beer

just wondered how many of you actual carry thermometers i got one cause i do fridge work as well

 

[ezzzekiel]

use rule of thumb method - x 0.8

 

[mouldy3]

I agree with the above. You only calculate in temperature when designing the size of the cable before installation.

 

[petewan]

Table 2D, Appendix 2, on-site guide

 

[fog]

Hi all

just been going through max zs etc and all the temperature changes


if i have got this right when you measure for R1 and R2 you take the temperature at the time. Apply a rating factor to get it ot 20 degrees and then when calculating zs or what ever to get to 70 degrees multiply it by 1.2 ?

I think simply this is to ensure thermal constraints are being met

ideas please

doin me ead in need another beer

just wondered how many of you actual carry thermometers i got one cause i do fridge work as well

Hi i agree need senior members feedback, just had my assessment recently was asked a similar question about zs, figures referenced regs and gave the assessor the zs figure from the regs he was pleased that I had used the regs correctly and found the information and then reminded me that we should due to thermal effects use the 0.8, or 80% rule of thumb rule for the given zs. I then insisted that the regs was a horrifying document to follow and when we do find what we are after, its a complete load of bo**ocks as we anly use 80% of the given table obviously when the table was written most of us was going to put cables in only in arctic conditions, I don't think so! lets just make it more confusing. (my assessor did not wish to comment but he was helpful on many other questions.)