Overload through-fault protection curve for a zig-zag trsf
Overload through-fault protection curve for a zig-zag trsf
(OP)
Hi
I want to draw the overload through-fault protection curve for a NEC. (zig-zag transformer, earthing transformer) The continious line current rating of the NEC is 60A, the short time line current rating is 400A for 30 seconds. Is there any way how I can plot this curve for values more than 400A? (Like the method describe in ANSI/IEEE transformer overload-through-fault standard - IEEE C37.91)
I have the nameplate details of the NEC - Voltage, Line/neutral currents and the measured Zo/phase - but don't know how to use it (if it is possible) to draw the curve for higher currents.
Thanks
I want to draw the overload through-fault protection curve for a NEC. (zig-zag transformer, earthing transformer) The continious line current rating of the NEC is 60A, the short time line current rating is 400A for 30 seconds. Is there any way how I can plot this curve for values more than 400A? (Like the method describe in ANSI/IEEE transformer overload-through-fault standard - IEEE C37.91)
I have the nameplate details of the NEC - Voltage, Line/neutral currents and the measured Zo/phase - but don't know how to use it (if it is possible) to draw the curve for higher currents.
Thanks
RCC






RE: Overload through-fault protection curve for a zig-zag trsf
I'm not sure what the standards say regarding short-time capability of zig-zag xfmr.
RE: Overload through-fault protection curve for a zig-zag trsf
RE: Overload through-fault protection curve for a zig-zag trsf
The zig-zag xfmr is without an external impedance (older installation), thus no current limitation, that is why I want to draw the overload through-fault protection curve.
jbartos:
Just explain transformer ignition curve, I'm not familiar with it?
Many thanks
RCC
RE: Overload through-fault protection curve for a zig-zag trsf
RE: Overload through-fault protection curve for a zig-zag trsf
400 amperes for 30 seconds is 4,800,000 A²∙sec. To some degree, can’t you extrapolate from that for other times?
RE: Overload through-fault protection curve for a zig-zag trsf
busbar: I'll give you a star for that one - I should have thought about it.
Thanks
RCC