ACE - ANSWER Used to determine the generation-load-interchange balance and
support interchange frequency.
Apparent Power - ANSWER In AC transmission, the measure of Volts times Amperes:
Voltamperes (VA)
Generation Shift Factor (GSF) - ANSWER percentage change of loading on line due to
generation. Use to determine redispatch amounts.
Governor Droop - ANSWER MW/Hz ratio 5% = 3 Hz range (60 x .05)
Power Transfer Distribution Factor (PTDF) - ANSWER percentage of change of
electrical loading on a line due to electrical power transfer (interchange) from one area to
another. Use to determine amount of interchange to curtail when transmission tie-lines are
overloaded, used in the Transmission Loading relief (TLR) process.
Outage Transfer Distribution Factor (OTDF) - ANSWER percentage of change of
electrical loading on a line due to electrical power transfer(interchange) from one area to
another while considering outages.
Distribution Factor (DF) - ANSWER Portion of an interchange transaction, typically
expressed in per unit that flows across a transmission facility (Flowgate).
1
, Interchange Distribution Calculator (IDC) - ANSWER The mechanism used by RCs in
the Eastern Interconnection to calculate the distribution of Interchange Transactions over
specific Flowgates. It includes a database of all Interchange Transactions and a matrix of the
Distribution Factors for the Eastern Interconnection.
Load Shift Factor (LSF) - ANSWER A factor to be applied to a load's expected change in
demand to determine the amount of flow contribution that change in demand will impose
on an identified transmission facility or monitored Flowgate.
System Operating Limit (SOL) - ANSWER The value (such as MW, MVar, Amperes,
Frequency or Volts) that satisfies the most limiting of the prescribed operating criteria for a
specified system configuration to ensure operation within acceptable reliability criteria.
System Operating Limits are based upon certain operating criteria. These include, but are
not limited to:
1) Facility Ratings (Applicable pre- and post-Contingency equipment or facility ratings)
2) Transient Stability Ratings (Applicable pre- and post-Contingency Stability Limits)
3) Voltage Stability Ratings (Applicable pre- and post-Contingency Voltage Stability)
4) System Voltage Limits (Applicable pre- and post-Contingency Voltage Limits)
OHMs Law - ANSWER V = I Z Voltage = Current x Impedance
Power (single phase) - ANSWER P = I V Power = Current x Voltage
Power (3 phase) - ANSWER P 3-phase = √3 x V line - line x I x pf
Total Power - ANSWER S = √3 x V line - line x I
System Load - ANSWER System Load = Total Generation - Net Interchange Actual
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support interchange frequency.
Apparent Power - ANSWER In AC transmission, the measure of Volts times Amperes:
Voltamperes (VA)
Generation Shift Factor (GSF) - ANSWER percentage change of loading on line due to
generation. Use to determine redispatch amounts.
Governor Droop - ANSWER MW/Hz ratio 5% = 3 Hz range (60 x .05)
Power Transfer Distribution Factor (PTDF) - ANSWER percentage of change of
electrical loading on a line due to electrical power transfer (interchange) from one area to
another. Use to determine amount of interchange to curtail when transmission tie-lines are
overloaded, used in the Transmission Loading relief (TLR) process.
Outage Transfer Distribution Factor (OTDF) - ANSWER percentage of change of
electrical loading on a line due to electrical power transfer(interchange) from one area to
another while considering outages.
Distribution Factor (DF) - ANSWER Portion of an interchange transaction, typically
expressed in per unit that flows across a transmission facility (Flowgate).
1
, Interchange Distribution Calculator (IDC) - ANSWER The mechanism used by RCs in
the Eastern Interconnection to calculate the distribution of Interchange Transactions over
specific Flowgates. It includes a database of all Interchange Transactions and a matrix of the
Distribution Factors for the Eastern Interconnection.
Load Shift Factor (LSF) - ANSWER A factor to be applied to a load's expected change in
demand to determine the amount of flow contribution that change in demand will impose
on an identified transmission facility or monitored Flowgate.
System Operating Limit (SOL) - ANSWER The value (such as MW, MVar, Amperes,
Frequency or Volts) that satisfies the most limiting of the prescribed operating criteria for a
specified system configuration to ensure operation within acceptable reliability criteria.
System Operating Limits are based upon certain operating criteria. These include, but are
not limited to:
1) Facility Ratings (Applicable pre- and post-Contingency equipment or facility ratings)
2) Transient Stability Ratings (Applicable pre- and post-Contingency Stability Limits)
3) Voltage Stability Ratings (Applicable pre- and post-Contingency Voltage Stability)
4) System Voltage Limits (Applicable pre- and post-Contingency Voltage Limits)
OHMs Law - ANSWER V = I Z Voltage = Current x Impedance
Power (single phase) - ANSWER P = I V Power = Current x Voltage
Power (3 phase) - ANSWER P 3-phase = √3 x V line - line x I x pf
Total Power - ANSWER S = √3 x V line - line x I
System Load - ANSWER System Load = Total Generation - Net Interchange Actual
2
