ERCOT System Operator Certification questions and
answers A+ Grade 2026\2027
There are electrical connections between ERCOT and the Eastern Interconnection. True or False?
- correct answer True, there are two DC ties connecting ERCOT with the Eastern Interconnection. There
are no closed AC ties.
In December, 2009, ERCOT's electrical market was changed from a Zonal to Nodal model. This means
that:
- correct answer Transmission system congestion is now managed between thousands of small points
(nodes) in the ERCOT system, rather than between a few large zones.
At a certain bus, current lags voltage by 72. What fraction of a cycle does this 72 phase lag correspond
to?
- correct answer 1/5th
What is the peak value of the voltage amplitude for a 345 KV AC voltage?
- correct answer 345/.707= 244 KV
What is the phase difference between the two vectors in each of the following pairs?
(1) 345<90 and 345<60
(2) 138<-90 and 138<+90
- correct answer (1) 30 , (2) 180
What is the per-unit value of a 345 KV bus voltage, if SCADA shows the actual bus voltage to be 358.8
KV? If operating criteria require voltage to be within 5% of the nominal value, is the bus voltage within
limits?
- correct answer 1.04, Yes
answers A+ Grade 2026\2027
There are electrical connections between ERCOT and the Eastern Interconnection. True or False?
- correct answer True, there are two DC ties connecting ERCOT with the Eastern Interconnection. There
are no closed AC ties.
In December, 2009, ERCOT's electrical market was changed from a Zonal to Nodal model. This means
that:
- correct answer Transmission system congestion is now managed between thousands of small points
(nodes) in the ERCOT system, rather than between a few large zones.
At a certain bus, current lags voltage by 72. What fraction of a cycle does this 72 phase lag correspond
to?
- correct answer 1/5th
What is the peak value of the voltage amplitude for a 345 KV AC voltage?
- correct answer 345/.707= 244 KV
What is the phase difference between the two vectors in each of the following pairs?
(1) 345<90 and 345<60
(2) 138<-90 and 138<+90
- correct answer (1) 30 , (2) 180
What is the per-unit value of a 345 KV bus voltage, if SCADA shows the actual bus voltage to be 358.8
KV? If operating criteria require voltage to be within 5% of the nominal value, is the bus voltage within
limits?
- correct answer 1.04, Yes
