Why only WYE? 230.95, GFPE on 1KA WYE

[Wire-Smith]

Whats the reasoning on the GFPE on 1KA solidly grounded WYE services and not other configurations.

Thanks.

 

[electrofelon]

The handbook states:

"....first required in the 1971 Code because of the unusually high number of burndowns reported on those types of service"

I dont know anything other than that.

 

[Wire-Smith]

The handbook states:

"....first required in the 1971 Code because of the unusually high number of burndowns reported on those types of service"

I dont know anything other than that.

i was thinking the ground fault on a wye leg might lower the voltage on the secondary of the transformer which might lower the current and slow down the ocpd from opening. i don't know. kind of like a high resistance fault, so the protection doesn't open as quickly, i.e. things burn longer.

free access doesn't have the comments from 71'

 

[Wire-Smith]

or the current on wye is from one winding while delta would be from multiple? so wye would be lower current and kind of same principle as last post. delta ground fault would be an three phase fault right? just spit balling, i don't have a grasp on this. delta I line= IPhase x 1.73 (sq. rt. of 3)
wye I line= I Phase

 

[Wire-Smith]

i found this study, it actually sounds like the reasoning is similar to what i was thinking but was mixing up delta and wye magnitudes, i don't know why they didn't do delta primary with grounded wye secondary.

but looks like grounded wye secondaries allow more fault current. i would think that would open standard ocpd quicker and have less of a need for supplemental ground fault protection. i think i am still missing something.


http://arpnjournals.com/jeas/research_papers/rp_2013/jeas_0813_923.pdf

From the finding, magnitude of fault current fromgenerator to fault location at the Yn-Yn transformerconfiguration had 26.893 kA. It is higher magnitude ofgenerator current for SLG fault at secondary side of thetransformer than other transformer configurations. In thiscondition, there was a route for zero sequence current toflow in a primary and secondary of the transformer. Themagnitude of SLG fault was similar for Yn-Y, Y-Yn, Y-Y,∆-Y and ∆-∆ configuration, which was 11.283 kA. Thelowest SLG fault from generator to fault location for Yn-∆and Y-∆ configuration was 8.697 kA.