ERCOT System Operator EXAM STUDY
GUIDE 2026/2027 ACCURATE QUESTIONS
WITH CORRECT DETAILED SOLUTIONS ||
100% GUARANTEED PASS
<NEWEST VERSION>
1. There are electrical connections between ERCOT and the Eastern
Interconnection. True or False? - ANSWER ✔ True, there are two DC ties
connecting ERCOT with the Eastern Interconnection. There are no closed
AC ties.
2. In December, 2009, ERCOT's electrical market was changed from a Zonal
to Nodal model. This means that: - ANSWER ✔ Transmission system
congestion is now managed between thousands of small points (nodes) in the
ERCOT system, rather than between a few large zones.
3. At a certain bus, current lags voltage by 72. What fraction of a cycle does
this 72 phase lag correspond to? - ANSWER ✔ 1/5th
4. What is the peak value of the voltage amplitude for a 345 KV AC voltage? -
ANSWER ✔ 345/.707= 244 KV
5. 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 - ANSWER ✔ (1) 30 , (2) 180
6. 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? -
ANSWER ✔ 1.04, Yes
,7. What is the unit of measurement for electric current? For capacitance? For
inductance? - ANSWER ✔ Amps / Farad / Henry
8. What are the essential components of an electric circuit? - ANSWER ✔
Voltage source, load, supply path, return path
9. For many actual electrical circuits, the earth serves as the return path for the
current flow. True or false? - ANSWER ✔ True
10.A resistance of 5 ohms is connected to a resistance of 10 ohms in an electric
circuit. What is the total resistance if the two resistances are connected (i) in
series and (ii) in parallel? - ANSWER ✔ (i) 15 ohms (ii) 3.33 ohms
11.The output of a generating unit is 500 MW. Express this value in watts. -
ANSWER ✔ 500,000,000 watts
12.All of the following are major North American interconnections EXCEPT:
a) Western Interconnection
b) Eastern Interconnection
c) ERCOT Interconnection
d) Southern Interconnection - ANSWER ✔ d) Southern
Interconnection
13.Which of the following are NOT part of ERCOT?
a) Dallas area
b) Houston area
c) San Antonio area
d) El Paso area - ANSWER ✔ d) El Paso area
14.There are electrical connections between ERCOT and the Eastern
Interconnection. True or false? - ANSWER ✔ True, there are two DC ties
connecting ERCOT with the Eastern Interconnection.
There are no closed AC ties.
15.In December, 2009, ERCOT's electrical market was changed from a Zonal
to Nodal
model. This means that:
, a) Transmission system congestion is now managed between
thousands of small
points (nodes) in the ERCOT system, rather than between a few large zones.
b) Generation resources are now all owned by ERCOT.
c) All transmission lines in ERCOT are controlled by ERCOT system operators
rather than the old wires companies
d) Transmission and generation companies are free to merge into single entities
once again. - ANSWER ✔ a) Transmission system congestion is now
managed between thousands of small
16.At a certain bus, current lags voltage by 72 . What fraction of a cycle does
this
72 phase lag correspond to?
a) 2/5th
b) 2/15th
c) 1/10th
d) 1/5th - ANSWER ✔ d) 1/5th
17.What is the peak value of the voltage amplitude for a 345 KV AC voltage?
a) 199 KV
b) 598 KV
c) 244 KV
d) 487.9 KV - ANSWER ✔ d) 487.9 KV
18.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
a) (1) 150 , (2) -90
b) (1) 30 , (2) 180
c) (1) -30 , (2) 0
d) (1) 150 , (2) -90 - ANSWER ✔ b) (1) 30 , (2) 180
19.When ERCOT is operating in an emergency condition such that a Credible
Single Contingency event could cause uncontrollable separation, cascading
outages, large-scale disruption of load, or overload of a transmission facility,
what does it issue? - ANSWER ✔ Emergency Notice
, 20.Where is an emergency notice posted electronically? - ANSWER ✔ MIS
public area
21.What does ERCOT employ to maintain system security and reliability? -
ANSWER ✔ CMPs and RASs
22.Under which conditions can ERCOT implement Block Load Transfer (BLT)
schemes? - ANSWER ✔ Watch, EEA, or local transmission constraints
23.What are considered critical loads for load restoration? - ANSWER ✔ (i)
Military facilities;
(ii) Facilities necessary to restore the electric utility system;
(iii) Law enforcement organizations and facilities affecting public health; and
(iv) Communication facilities.
24.What EEA level will be implemented when the clock-minute average system
frequency falls below 59.91 Hz for 25 consecutive minutes, or below 59.5
Hz for any duration? - ANSWER ✔ EEA Level 3
25.At what point during EEA level 3 does firm load shedding occur? -
ANSWER ✔ When PRC falls below 1000 MW
26.What is the purpose of firm load shedding? - ANSWER ✔ Arrest
frequency decay to prevent generator tripping
27.What is it called when ERCOT does the RUC process after the DRUC? -
ANSWER ✔ HRUC
28.Which Emerency notice is issued when PRC falls below 2,300 MW and is
not projected to be recovered above 2,300 MW within 30 minutes? -
ANSWER ✔ EEA Level 1
29.What ERS is deployed during EEA Level 1? - ANSWER ✔ ERS-30
30.Which Emergency Notice is issued when the clock-minute average system
frequency falls below 59.91 Hz for 15 consecutive minutes or when PRC
falls below 1750 MW? - ANSWER ✔ EEA Level 2
GUIDE 2026/2027 ACCURATE QUESTIONS
WITH CORRECT DETAILED SOLUTIONS ||
100% GUARANTEED PASS
<NEWEST VERSION>
1. There are electrical connections between ERCOT and the Eastern
Interconnection. True or False? - ANSWER ✔ True, there are two DC ties
connecting ERCOT with the Eastern Interconnection. There are no closed
AC ties.
2. In December, 2009, ERCOT's electrical market was changed from a Zonal
to Nodal model. This means that: - ANSWER ✔ Transmission system
congestion is now managed between thousands of small points (nodes) in the
ERCOT system, rather than between a few large zones.
3. At a certain bus, current lags voltage by 72. What fraction of a cycle does
this 72 phase lag correspond to? - ANSWER ✔ 1/5th
4. What is the peak value of the voltage amplitude for a 345 KV AC voltage? -
ANSWER ✔ 345/.707= 244 KV
5. 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 - ANSWER ✔ (1) 30 , (2) 180
6. 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? -
ANSWER ✔ 1.04, Yes
,7. What is the unit of measurement for electric current? For capacitance? For
inductance? - ANSWER ✔ Amps / Farad / Henry
8. What are the essential components of an electric circuit? - ANSWER ✔
Voltage source, load, supply path, return path
9. For many actual electrical circuits, the earth serves as the return path for the
current flow. True or false? - ANSWER ✔ True
10.A resistance of 5 ohms is connected to a resistance of 10 ohms in an electric
circuit. What is the total resistance if the two resistances are connected (i) in
series and (ii) in parallel? - ANSWER ✔ (i) 15 ohms (ii) 3.33 ohms
11.The output of a generating unit is 500 MW. Express this value in watts. -
ANSWER ✔ 500,000,000 watts
12.All of the following are major North American interconnections EXCEPT:
a) Western Interconnection
b) Eastern Interconnection
c) ERCOT Interconnection
d) Southern Interconnection - ANSWER ✔ d) Southern
Interconnection
13.Which of the following are NOT part of ERCOT?
a) Dallas area
b) Houston area
c) San Antonio area
d) El Paso area - ANSWER ✔ d) El Paso area
14.There are electrical connections between ERCOT and the Eastern
Interconnection. True or false? - ANSWER ✔ True, there are two DC ties
connecting ERCOT with the Eastern Interconnection.
There are no closed AC ties.
15.In December, 2009, ERCOT's electrical market was changed from a Zonal
to Nodal
model. This means that:
, a) Transmission system congestion is now managed between
thousands of small
points (nodes) in the ERCOT system, rather than between a few large zones.
b) Generation resources are now all owned by ERCOT.
c) All transmission lines in ERCOT are controlled by ERCOT system operators
rather than the old wires companies
d) Transmission and generation companies are free to merge into single entities
once again. - ANSWER ✔ a) Transmission system congestion is now
managed between thousands of small
16.At a certain bus, current lags voltage by 72 . What fraction of a cycle does
this
72 phase lag correspond to?
a) 2/5th
b) 2/15th
c) 1/10th
d) 1/5th - ANSWER ✔ d) 1/5th
17.What is the peak value of the voltage amplitude for a 345 KV AC voltage?
a) 199 KV
b) 598 KV
c) 244 KV
d) 487.9 KV - ANSWER ✔ d) 487.9 KV
18.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
a) (1) 150 , (2) -90
b) (1) 30 , (2) 180
c) (1) -30 , (2) 0
d) (1) 150 , (2) -90 - ANSWER ✔ b) (1) 30 , (2) 180
19.When ERCOT is operating in an emergency condition such that a Credible
Single Contingency event could cause uncontrollable separation, cascading
outages, large-scale disruption of load, or overload of a transmission facility,
what does it issue? - ANSWER ✔ Emergency Notice
, 20.Where is an emergency notice posted electronically? - ANSWER ✔ MIS
public area
21.What does ERCOT employ to maintain system security and reliability? -
ANSWER ✔ CMPs and RASs
22.Under which conditions can ERCOT implement Block Load Transfer (BLT)
schemes? - ANSWER ✔ Watch, EEA, or local transmission constraints
23.What are considered critical loads for load restoration? - ANSWER ✔ (i)
Military facilities;
(ii) Facilities necessary to restore the electric utility system;
(iii) Law enforcement organizations and facilities affecting public health; and
(iv) Communication facilities.
24.What EEA level will be implemented when the clock-minute average system
frequency falls below 59.91 Hz for 25 consecutive minutes, or below 59.5
Hz for any duration? - ANSWER ✔ EEA Level 3
25.At what point during EEA level 3 does firm load shedding occur? -
ANSWER ✔ When PRC falls below 1000 MW
26.What is the purpose of firm load shedding? - ANSWER ✔ Arrest
frequency decay to prevent generator tripping
27.What is it called when ERCOT does the RUC process after the DRUC? -
ANSWER ✔ HRUC
28.Which Emerency notice is issued when PRC falls below 2,300 MW and is
not projected to be recovered above 2,300 MW within 30 minutes? -
ANSWER ✔ EEA Level 1
29.What ERS is deployed during EEA Level 1? - ANSWER ✔ ERS-30
30.Which Emergency Notice is issued when the clock-minute average system
frequency falls below 59.91 Hz for 15 consecutive minutes or when PRC
falls below 1750 MW? - ANSWER ✔ EEA Level 2
