Power Line Capacity Assessment
Power Line Capacity Assessment
(OP)
WE are working on adding a redundant (M-T-M)substation to existing redundant 72 kV power line circuits, each uses 795 kcmil, "Drake" ACSR. Our load, when added, would result to a line estimated maximum electrical loading of 105 MVA at 72 kV during a CONTIGENCY CASE (WHEN THE BUE TIE IS CLOSED AND ONE POWER LINE IS SUPPLYING POWER TO THE ENTIRE LOADS).
The installed 72 kV circuits are Southwire 795 kcmil, "Drake" ACSR with the ACSR design specification as attached. The design basis for this ACSR was 100 Deg C Conductor temperature at maximum sag with ambient of 32 Deg C with wind and at 1,020 A load current.
However, I would think that when these power lines are already built, the capacity assessment would not use "design values" but worst case minimum. The ACSR data obtained from Southwire lists different ampacities at 100 Deg C conductor temperature and we are at a confusion and debate as which would be used.
Can we use 826 A for normal conditions and use 1060 A for CONTINGENCY CONDITIONS when one power line is down and all bus tie circuit breakers will be closed and one incomer open in all substations fed from these redundant lines?
Regards
The installed 72 kV circuits are Southwire 795 kcmil, "Drake" ACSR with the ACSR design specification as attached. The design basis for this ACSR was 100 Deg C Conductor temperature at maximum sag with ambient of 32 Deg C with wind and at 1,020 A load current.
However, I would think that when these power lines are already built, the capacity assessment would not use "design values" but worst case minimum. The ACSR data obtained from Southwire lists different ampacities at 100 Deg C conductor temperature and we are at a confusion and debate as which would be used.
Can we use 826 A for normal conditions and use 1060 A for CONTINGENCY CONDITIONS when one power line is down and all bus tie circuit breakers will be closed and one incomer open in all substations fed from these redundant lines?
Regards






RE: Power Line Capacity Assessment
RE: Power Line Capacity Assessment
RE: Power Line Capacity Assessment
If the line has significant voltage drop or your operating voltage is less than 72 kV, you should also inquire whether the utility uses thermal limits in expressed in amperes or express as MVA calculated using nominal system voltage.
Are you in Canada or Scandinavia? 57N latitude drops your solar input a fair amount. Some utilities also use a time slightly later in the afternoon to coincide the typical maximum load/temperature of the day.
RE: Power Line Capacity Assessment
Bill
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"Why not the best?"
Jimmy Carter
RE: Power Line Capacity Assessment
Waross, our tap changer AVR set point is set at 100% nominal 72 kV secondary, in this case I would think that our secondary voltage will be fixed at 100% nominal 72 kV at the transformer 72 kV bus.
Regards
RE: Power Line Capacity Assessment
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Power Line Capacity Assessment