NERC Study Set Latest Update - 250

NERC Study Set Latest Update - 250 Questions and 100% Verified Correct Answers Actual Exam Guaranteed A+

______ is the device with moving blades that extracts energy from a flowing substance ( air , water , or steam ) pushing against its blades and converts it to electrical energy by turning a generator .

•A turbine •A reactor •An exciter •A field winding

•An armature winding - CORRECT ANSWER: •A turbine

A 1500 MVA transformer has been de - rated 15 % due to a cooling system failure .What is the new MVA rating ?

•1275 MVA

•1000 MVA

•750 MVA

•1485 MVA - CORRECT ANSWER: •1275 MVA

A 500 MW generator in your Balancing Area has a droop setting of 5 % . It is currently operating at 300 MWs . If frequency of the Interconnection dropped to 59.94 , what is the resulting MW output of the generator?

•400 MWs •325 MWs •290 MWs 1 / 4

•310 MWs - CORRECT ANSWER: •310 MWs

A 500 MW generator trips in a Balancing Authority outside your Balancing Authority Area . Which of the following responses would you expect to see in your area?

•Frequency above 60 Hz •Net Actual Interchange greater than Scheduled Interchange •Reduced Net Actual Interchange

•Reduced net generation on your system - CORRECT ANSWER: •Net Actual

Interchange greater than Scheduled Interchange

A 700 MW generator in a Balancing Authority area trips due to operator error . Which control system on the remaining generators would respond to the drop in system frequency resulting from the loss of generation?

•Automatic voltage regulators •Special protection systems •Differential relay systems

•Governor control systems - CORRECT ANSWER: •Governor control systems

A Balancing Authority experiences a Reportable Balancing Contingency Event which results in ACE dropping to -540 MW . The BA's ACE was 0 prior to the event . Ten minutes into the recovery , a 150 MW generator trips , resulting in ACE dropping again .What must the BA return its ACE to by the end of the recovery period to be compliant ?

• 390 MW

• -150 MW

• 150 MW

• 0 MW - CORRECT ANSWER: • -150MW

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A Balancing Authority has 600 MW generator which is determined to be its MSSC . How much contingency reserve is the BA required to have available?

•480 MW

•660 MW

•600 MW

•500 MW - CORRECT ANSWER: •600 MW

A Balancing Authority has a normal load of around 8500 MW . Its most severe single contingency is a 700 MW coal - fired steam unit . At 0810 , the ACE value was at -55 MW when a 600 MW generator in the Balancing Authority's northern area tripped off line due to a generator differential . This event resulted in a large negative ACE for the Balancing Authority . What value must ACE return to and in what time frame to avoid a DCS violation?

• Zero ACE in 15 minutes • 55 MW ACE in 10 minutes • Zero ACE in 10 minutes

• -55 MW ACE in 15 minutes - CORRECT ANSWER: • -55 MW ACE in 15 minutes

A Balancing Authority has a tie - line meter that has been verified reading 5 MWs high .The flow on the tie line is out of the BA's Area . What effect will this have on the ACE reading?

•ACE will not be affected by the inaccurate reading •lt depends on whether frequency is high or low •ACE will read 5 MW above its actual value •ACE will read 5 MW below its actual value - CORRECT ANSWER: •ACE will read 5 MW above its actual value

A Balancing Authority has an ACE of -50 MW when Interconnection frequency is 60.04 Hz .Is the BA in danger of exceeding the Balancing Authority ACE Limit (BAAL) 3 / 4

•Yes if the BA's Frequency Bias is less than or equal to -100MW / .1 Hz •Yes , if the BA's Frequency Bias is greater than -100MW / .1 Hz •No , there is no low BAAL when frequency is high - CORRECT ANSWER: •No , there is no low BAAL when frequency is high

A Balancing Authority has discovered one tie line meter reading is off by 30 MW , causing the ACE values to be incorrect What should be done to temporarily adjust for the error until the meter can be calibrated or repaired ?

•Take the numbers from the incorrect tie line and insert them into the Nls portion of the ACE equation •Change the Frequency Bias part of the ACE equation to reflect the error •Use the IME portion of the equation to adjust for the meter error

•Change the AGC mode to Flat Frequency Control - CORRECT ANSWER: •Use the

IME portion of the equation to adjust for the meter error

A Balancing Authority has lost the ability to calculate Reporting ACE starting at 13:15 .At 13:45 , capability has not been restored . The Balancing Authority must notify the Reliability Coordinator before what time?

•No notification is required

•14:00

•14:15

•14:45 - CORRECT ANSWER: •14:00

A Balancing Authority has one of its tie - line meters out of service for maintenance .Which of the following actions would be appropriate for operating the area on Automatic Generation Control?

•Use the Meter Error part of the ACE equation and remain in Tie - Line Bias mode

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