hi odlanor,
while I am trying to digest all of the helpful tips by you and others, could you please clarify what you mean by:
You should set it at the "amps at 230kV side seen by a fault to ground at 34.5kV"?
thanks
so, say if I set the 51G or 51N of the 34.5kV system to 300A pickup, should I also set the pickup of the 51G at 230kV side at 300Amps? Or should I set it at the "equivalent amps at 230kV side which is around 47A?
I am a bit confused on how to plot that in TCC since they are of different voltage...
thanks for the replies guys.
however, there is another issue that I am in doubt. apparently, the other end of the 34.5kV is also resistor grounded. I have attached the single line diagram for reference. what would be the resulting ground fault current if there will be ground fault in the middle...
I am working on a ground o/c coordination and i am having a bit of trouble on the wye-resistor grounded wye-solid grounded with delta tertiary transformer. Solidly grounded is connected at 230kV while the resistor grounded (50ohms) is connected at 34.5kV. Now, my questions is:
1. Will a ground...
thanks again for the inputs guys, sorry it took me long to reply, as I was dragged again in another problem in the Plant.
The transformers are identical units.
the discussions are great, though I haven't digest all... and still haven't get the chance to clamp a PQ meter!
thanks again for the valuable inputs.
jghrist, its been a normal practice for us to measure line-to-line and line-to-ground voltages during routine check of power distribution. and its been this case where we found unbalanced line-to-ground voltage with no grounded phase at the load side. the...
thanks for all your inputs.
waross,
could you kindly explain what do you mean by "significant meter loading"? We used the same DMM with the adjacent transformer bank (ungrounded wye-delta) and measured balanced voltages (line-ground).
actually, one transformer was used for 240V service (but...
the subject is 3-100kVA, ungrounded wye-delta transformer bank, 2400/4160Y-240/480V. During a spot check-up on this bank, we were surprised with the line-ground voltages 302V/320V/198V that were measured between the secondary terminals and the tank equipment grounding (as ground point). thinking...
thanks waross & jraef for your replies. We do have some old equipment and I was surprised to know that two overload heaters were used then. Actually had some "discussions" with the "seasoned" engineers here but no one could explain the theory behind the two-overloads scheme. They are all saying...
Hi,
I would like to be "enlightened" on the basic Code requirements about motor overload protection.
1. What is the rationale with the now NEC requirement of having 3-Overload relays for 3-phase motors, versus the then allowed 2-overload relays for 3-phase motors.
2. What's the reason behind...
