Practice Test NERC Questions and answers | updated 2024

Practice Test NERC Questions and answers | updated 2024 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? - 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? - 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? - 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? - 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? - Turbine Reactive reserve response during a disturbance is best obtained from which devise? - 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? - A produces more reactive power than B. Lightly loaded transmission lines essentially behave like? - 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? - 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? - 63% Which statement best describes how reactive power MVAR power normally flows? - High Voltage to Low Voltage Which of the following types of data are BA and RC not required to share with one another? - 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? - Planned outages of generation units A 1000 MVA rated generator that produces 800 MW and 100 MVAR is best described as? - Operating in a lagging mode. Inductive system Which of the following types of MW load is the most impacted by an intentional frequency reduction? - 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? - Angle Instability The phase voltage in a wye-connected load is 277 V. What is the line to line voltage? - 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? - 300 MW and No The best prediction of system load is the load forecast tool that uses? - 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? - 1/10 of 360 so 36 A ___________ tool is used to ensure the power system can respond within acceptable limits of N-1 - Contingency Analysis Which of the following activities would not be included in the procedures for transmission reliability? - 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. - 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 - 20 mw and Inductive How many MVARs does a 230 kV, 50 MVAR capacitor bank provide when the voltage id 207 kV - 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? - 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 - 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? - Increase The actual voltage is 362kV on a 345 bus. What is the p.u. voltage? - 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? - 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? - 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? - 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? - Shed Load The transmission operator shall take corrective actions necessary to prevent voltage