Thermal Overload Protection for cables, dry type xfr.
Thermal Overload Protection for cables, dry type xfr.
(OP)
Dear Colleagues.
Do we have some standard for the thermal overload curve in digital relays? It's some exponential curve.
I see in many relays eqv.
Teta (termal capacity)=
(I/1.05 x I (FLC/FLA))^2 x (1- e^(t/t(time constant)) x 100%
What is a source of this eqv?
I don't know why, but I think it's BS142 standard.
What is a ANSI/IEEE standard for 49 curves ( if any)?
Thanks for your help.
Regards.
Slava
Do we have some standard for the thermal overload curve in digital relays? It's some exponential curve.
I see in many relays eqv.
Teta (termal capacity)=
(I/1.05 x I (FLC/FLA))^2 x (1- e^(t/t(time constant)) x 100%
What is a source of this eqv?
I don't know why, but I think it's BS142 standard.
What is a ANSI/IEEE standard for 49 curves ( if any)?
Thanks for your help.
Regards.
Slava






RE: Thermal Overload Protection for cables, dry type xfr.
See http
Also the Areva NPAG Chapter 19 on motor protection has some similar equations and curves illustrated.
Also, the following paper may be of interest:-
ht
Regards
Marmite
RE: Thermal Overload Protection for cables, dry type xfr.
Thanks a lot.
You are great!!!!!
Today it's IEC60255-8 (1990).
Best Regards.
Slava.