NERC Practice Test Questions with
complete solutions 2025
A .transmission .line .is .operating .with .a .voltage .phase .angle .different .of .30
.degrees .between .the .sending .Vs .and .the .receiving .bus .Vr. .If .the .receiving .end
.load .is .suddenly .increased, .the .voltage .phase .angle .difference .will .be? .- .ANS✓
✓-The .phase .angle .will .increase. .When .load .is .increased .phase .angle .will
.increase.
A .load .has .a .power .factor .of .0.9 .lagging. .If .the .load .draws .100 .MVA, .what .is
.the .MW .draw? .- .ANS✓✓-90 .pf= .mw/mva
The .high .side .of .a .delta-wye .connection .transformer .is .connected .to .a .power
.system .with .199 .kV .L-G .high .side .voltage. .What .is .the .voltage .across .the .delta
.winding .of .the .transformer? .- .ANS✓✓-Vl-l= .square .root .of .3 .times .Vl-g
.1.73x191= .345kV
If .a .transmission .line .is .carrying .400 .MW .and .300 .MVAR .what .is .the .MVA? .-
.ANS✓✓-3-4-5 .triangle .500 .MVA
The .prime .mover .is .the .component .of .the .generator .that .creates .the .rotational
.force. .In .a .typical .coal .fired .steam .generator .what .component .spins .the .rotor?
.- .ANS✓✓-Turbine
Reactive .reserve .response .during .a .disturbance .is .best .obtained .from .which
.devise? .- .ANS✓✓-Synchronous .condensers
For .two .identically .constructed .transmission .lines .where .Line .A .is .150 .miles
.long .and .line .B .is .15 .miles .long, .if .both .lines .are .lightly .loaded? .- .ANS✓✓-A
.produces .more .reactive .power .than .B.
Lightly .loaded .transmission .lines .essentially .behave .like? .- .ANS✓✓-Shunt
.Capacitors
You .receive .an .alarm .that .indicates .low .oil .pressure .on .an .underground
.transmission .cable. .SCADA .shows .the .pressure .is .continuing .to .drop. .What .is
.the .first .step .you .take .to .protect .the .line? .- .ANS✓✓-Isolate .the .line
Computer .simulations .show .that .for .a .100 .MW .schedule .from .Bus .A .to .Bus .B,
.63% .of .the .schedule .will .flow .on .the .scheduled .path .and .the .remainder .will
,.flow .on .other .parallel .paths. .What .is .the .distribution .factor .for .the .scheduled
.path? .- .ANS✓✓-63%
Which .statement .best .describes .how .reactive .power .MVAR .power .normally
.flows? .- .ANS✓✓-High .Voltage .to .Low .Voltage
Which .of .the .following .types .of .data .are .BA .and .RC .not .required .to .share .with
.one .another? .- .ANS✓✓-Generator .start .up .cost
TOP .must .develop, .maintain, .and .implement .formal .policies .and .procedures .to
.provide .for .transmission .reliability. .Which .of .the .following .DOES .NOT .need .to
.be .addressed .in .these .policies .and .procedures? .- .ANS✓✓-Planned .outages .of
.generation .units
A .1000 .MVA .rated .generator .that .produces .800 .MW .and .100 .MVAR .is .best
.described .as? .- .ANS✓✓-Operating .in .a .lagging .mode. .Inductive .system
Which .of .the .following .types .of .MW .load .is .the .most .impacted .by .an .intentional
.frequency .reduction? .- .ANS✓✓-Motor
Assume .there .are .two .250 .mile .long .transmission .lines .exporting .an .excessive
.amount .of .MW .from .a .generation .area .to .a .load .area. .One .of .the .lines .suddenly
.trips .and .the .area .power .system .collapses .within .a .few .seconds. .The .most
.likely .cause .of .the .collapse? .- .ANS✓✓-Angle .Instability
The .phase .voltage .in .a .wye-connected .load .is .277 .V. .What .is .the .line .to .line
.voltage? .- .ANS✓✓-480 .V
A .simple .power .system .is .composed .of .three .lines .connecting .generation .to
.load. .Each .lines .the .same .impedance, .is .initially .loaded .at .200 .MW, .and .has .a
.thermal .limit .of .400 .MW. .If .one .line .trips, .what .the .loading .on .the .shortest
.remaining .line .be .and .will .the .thermal .limit .either .remaining .line .be .violated? .-
.ANS✓✓-300 .MW .and .No
The .best .prediction .of .system .load .is .the .load .forecast .tool .that .uses? .- .ANS✓
✓-Forecasted .Weather
If .the .phase .angel .at .an .open .breaker .is .equal .to .1/10 .of .a .cycle, .this .is .the .the
.same .angle .as? .- .ANS✓✓-1/10 .of .360 .so .36
A .___________ .tool .is .used .to .ensure .the .power .system .can .respond .within
.acceptable .limits .of .N-1 .- .ANS✓✓-Contingency .Analysis
Which .of .the .following .activities .would .not .be .included .in .the .procedures .for
.transmission .reliability? .- .ANS✓✓-Ancillary .service .pricing
, The .transmission .Operator .and .BA .shall .provide .documentation .that .operating
.personnel .have .______ .to .implement .real .time .actions .to .ensure .the .stable .and
.reliable .operation .of .the .BES. .- .ANS✓✓-Proper .NERC .Certification .Credential
A .utility .distribution .bus .has .the .following .customer .loads .attached. .What .is
.the .total .customer .MW .load .and .is .the .total .customer .load .capacitive .or
.inductive? .5 .MW .1 .MVAR .& .3 .MW .1 .MVAR .& .2 .MW .-2 .MVAR .& .10 .MW .3 .MVAR
.- .ANS✓✓-20 .mw .and .Inductive
How .many .MVARs .does .a .230 .kV, .50 .MVAR .capacitor .bank .provide .when .the
.voltage .id .207 .kV .- .ANS✓✓-Actual .MW/ .Rated .MW .^2 .x .Capacitor .Rating
40
You .are .a .system .operator .and .the .load .forecast .is .for .an .all .time .summer .peak
.load .day, .generations .and .reactive .resources .will .be .tight. .Which .scheduled .job
.would .you .allow .to .proceed? .- .ANS✓✓-735 .kV .shunt .reactor .maintenance.
A .contingency .results .in .the .exceedance .of .an .IROL. .What .could .be .the .result
.if .the .IROL .is .allowed .to .be .exceeded .longer .than .T .sub .v .- .ANS✓✓-
Interruption .of .power .to .a .large .part .of .the .BES
Generators .have .the .ability .to .be .used .as .voltage .control .devices. .If .a .generator
.raises .its .VAR .output, .the .system .orator .should .expect .system .stage .to? .- .ANS
✓✓-Increase
The .actual .voltage .is .362kV .on .a .345 .bus. .What .is .the .p.u. .voltage? .- .ANS✓✓-
1.05
In .the .initial .stages .of .a .system .restoration .condition .high .transmission .system
.voltage .problems .are .more .likely .than .low .transmission .system .voltage
.problems .why? .- .ANS✓✓-Because .of .excessive .MVAR .supply .from .the
.energization .of .transmission .lines
All .transmission .operators .shall .operate .so .that .instability .uncontrolled
.separation .or .cascading .outages .will .not .occur .in .result .of? .- .ANS✓✓-Most
.severe .single .contingency .MSSC
A .230kV .transmission .line .is .energized .at .230kV .and .is .100 .miles .long. .What .is
.the .approximate .line .charging .contribution? .- .ANS✓✓-30MVAR
When .the .system .is .on .the .verge .of .a .voltage .collapse .and .nothing .else .can .be
.done .to .alleviate .the .problem, .operating .personnel .should? .- .ANS✓✓-Shed
.Load
The .transmission .operator .shall .take .corrective .actions .necessary .to .prevent
.voltage .collapse .when .reactive .resources .are .insufficient .including? .- .ANS✓✓-
Shedding .Load
complete solutions 2025
A .transmission .line .is .operating .with .a .voltage .phase .angle .different .of .30
.degrees .between .the .sending .Vs .and .the .receiving .bus .Vr. .If .the .receiving .end
.load .is .suddenly .increased, .the .voltage .phase .angle .difference .will .be? .- .ANS✓
✓-The .phase .angle .will .increase. .When .load .is .increased .phase .angle .will
.increase.
A .load .has .a .power .factor .of .0.9 .lagging. .If .the .load .draws .100 .MVA, .what .is
.the .MW .draw? .- .ANS✓✓-90 .pf= .mw/mva
The .high .side .of .a .delta-wye .connection .transformer .is .connected .to .a .power
.system .with .199 .kV .L-G .high .side .voltage. .What .is .the .voltage .across .the .delta
.winding .of .the .transformer? .- .ANS✓✓-Vl-l= .square .root .of .3 .times .Vl-g
.1.73x191= .345kV
If .a .transmission .line .is .carrying .400 .MW .and .300 .MVAR .what .is .the .MVA? .-
.ANS✓✓-3-4-5 .triangle .500 .MVA
The .prime .mover .is .the .component .of .the .generator .that .creates .the .rotational
.force. .In .a .typical .coal .fired .steam .generator .what .component .spins .the .rotor?
.- .ANS✓✓-Turbine
Reactive .reserve .response .during .a .disturbance .is .best .obtained .from .which
.devise? .- .ANS✓✓-Synchronous .condensers
For .two .identically .constructed .transmission .lines .where .Line .A .is .150 .miles
.long .and .line .B .is .15 .miles .long, .if .both .lines .are .lightly .loaded? .- .ANS✓✓-A
.produces .more .reactive .power .than .B.
Lightly .loaded .transmission .lines .essentially .behave .like? .- .ANS✓✓-Shunt
.Capacitors
You .receive .an .alarm .that .indicates .low .oil .pressure .on .an .underground
.transmission .cable. .SCADA .shows .the .pressure .is .continuing .to .drop. .What .is
.the .first .step .you .take .to .protect .the .line? .- .ANS✓✓-Isolate .the .line
Computer .simulations .show .that .for .a .100 .MW .schedule .from .Bus .A .to .Bus .B,
.63% .of .the .schedule .will .flow .on .the .scheduled .path .and .the .remainder .will
,.flow .on .other .parallel .paths. .What .is .the .distribution .factor .for .the .scheduled
.path? .- .ANS✓✓-63%
Which .statement .best .describes .how .reactive .power .MVAR .power .normally
.flows? .- .ANS✓✓-High .Voltage .to .Low .Voltage
Which .of .the .following .types .of .data .are .BA .and .RC .not .required .to .share .with
.one .another? .- .ANS✓✓-Generator .start .up .cost
TOP .must .develop, .maintain, .and .implement .formal .policies .and .procedures .to
.provide .for .transmission .reliability. .Which .of .the .following .DOES .NOT .need .to
.be .addressed .in .these .policies .and .procedures? .- .ANS✓✓-Planned .outages .of
.generation .units
A .1000 .MVA .rated .generator .that .produces .800 .MW .and .100 .MVAR .is .best
.described .as? .- .ANS✓✓-Operating .in .a .lagging .mode. .Inductive .system
Which .of .the .following .types .of .MW .load .is .the .most .impacted .by .an .intentional
.frequency .reduction? .- .ANS✓✓-Motor
Assume .there .are .two .250 .mile .long .transmission .lines .exporting .an .excessive
.amount .of .MW .from .a .generation .area .to .a .load .area. .One .of .the .lines .suddenly
.trips .and .the .area .power .system .collapses .within .a .few .seconds. .The .most
.likely .cause .of .the .collapse? .- .ANS✓✓-Angle .Instability
The .phase .voltage .in .a .wye-connected .load .is .277 .V. .What .is .the .line .to .line
.voltage? .- .ANS✓✓-480 .V
A .simple .power .system .is .composed .of .three .lines .connecting .generation .to
.load. .Each .lines .the .same .impedance, .is .initially .loaded .at .200 .MW, .and .has .a
.thermal .limit .of .400 .MW. .If .one .line .trips, .what .the .loading .on .the .shortest
.remaining .line .be .and .will .the .thermal .limit .either .remaining .line .be .violated? .-
.ANS✓✓-300 .MW .and .No
The .best .prediction .of .system .load .is .the .load .forecast .tool .that .uses? .- .ANS✓
✓-Forecasted .Weather
If .the .phase .angel .at .an .open .breaker .is .equal .to .1/10 .of .a .cycle, .this .is .the .the
.same .angle .as? .- .ANS✓✓-1/10 .of .360 .so .36
A .___________ .tool .is .used .to .ensure .the .power .system .can .respond .within
.acceptable .limits .of .N-1 .- .ANS✓✓-Contingency .Analysis
Which .of .the .following .activities .would .not .be .included .in .the .procedures .for
.transmission .reliability? .- .ANS✓✓-Ancillary .service .pricing
, The .transmission .Operator .and .BA .shall .provide .documentation .that .operating
.personnel .have .______ .to .implement .real .time .actions .to .ensure .the .stable .and
.reliable .operation .of .the .BES. .- .ANS✓✓-Proper .NERC .Certification .Credential
A .utility .distribution .bus .has .the .following .customer .loads .attached. .What .is
.the .total .customer .MW .load .and .is .the .total .customer .load .capacitive .or
.inductive? .5 .MW .1 .MVAR .& .3 .MW .1 .MVAR .& .2 .MW .-2 .MVAR .& .10 .MW .3 .MVAR
.- .ANS✓✓-20 .mw .and .Inductive
How .many .MVARs .does .a .230 .kV, .50 .MVAR .capacitor .bank .provide .when .the
.voltage .id .207 .kV .- .ANS✓✓-Actual .MW/ .Rated .MW .^2 .x .Capacitor .Rating
40
You .are .a .system .operator .and .the .load .forecast .is .for .an .all .time .summer .peak
.load .day, .generations .and .reactive .resources .will .be .tight. .Which .scheduled .job
.would .you .allow .to .proceed? .- .ANS✓✓-735 .kV .shunt .reactor .maintenance.
A .contingency .results .in .the .exceedance .of .an .IROL. .What .could .be .the .result
.if .the .IROL .is .allowed .to .be .exceeded .longer .than .T .sub .v .- .ANS✓✓-
Interruption .of .power .to .a .large .part .of .the .BES
Generators .have .the .ability .to .be .used .as .voltage .control .devices. .If .a .generator
.raises .its .VAR .output, .the .system .orator .should .expect .system .stage .to? .- .ANS
✓✓-Increase
The .actual .voltage .is .362kV .on .a .345 .bus. .What .is .the .p.u. .voltage? .- .ANS✓✓-
1.05
In .the .initial .stages .of .a .system .restoration .condition .high .transmission .system
.voltage .problems .are .more .likely .than .low .transmission .system .voltage
.problems .why? .- .ANS✓✓-Because .of .excessive .MVAR .supply .from .the
.energization .of .transmission .lines
All .transmission .operators .shall .operate .so .that .instability .uncontrolled
.separation .or .cascading .outages .will .not .occur .in .result .of? .- .ANS✓✓-Most
.severe .single .contingency .MSSC
A .230kV .transmission .line .is .energized .at .230kV .and .is .100 .miles .long. .What .is
.the .approximate .line .charging .contribution? .- .ANS✓✓-30MVAR
When .the .system .is .on .the .verge .of .a .voltage .collapse .and .nothing .else .can .be
.done .to .alleviate .the .problem, .operating .personnel .should? .- .ANS✓✓-Shed
.Load
The .transmission .operator .shall .take .corrective .actions .necessary .to .prevent
.voltage .collapse .when .reactive .resources .are .insufficient .including? .- .ANS✓✓-
Shedding .Load
