NERC CERTIFICATION EXAM TEST BANK | CONTAINS EXPERT VERIFIED QUESTIONS AND ANSWERS | GUARA, Exams of Engineering

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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-VI-I= square root of 3 times VI-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 startup 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 The MSSC for your BA Area is 850 MW. A defined disturbance for DCS reporting would be qual to how many MWs? - ANS-680 Of the following which would be the best indicator of voltage collapse prone conditions? - ANS-Low reactive power reserves If the phase angle adds an open breaker is equal to 1/10 of a cycle this is the same as an angle of degrees - ANS-36 A Tool is used to ensure the power system can respond within acceptable limits N-1conditions? - ANS-Contingency analysis Transmission operator and balancing authority shall provide documentation that operation personnel have the. to implement real-time actions to ensure the stable and reliable operation of the bulk electric system. - ANS-Proper NERC certification credential How many MVAR does a 230 kV, 50 MVAR capacitor bank provide when the voltage is 207 kV? - ANS-40 MVAR You are a system operator in the load forecast is for an all-time summer peak load day, generation 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 accidents of a IROL.What could be the result if the IROL is allowed to be exceeded longer than its Tv? - 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 operator should expect this system voltage to? - ANS- Increase The actual voltage is 362 kV on a 345-caliber bus. What is the p.u. voltage? - ANS- Actual/nominal x 100. 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 Reactive resources are used to? - ANS-Maintain acceptable voltage levels All TOP shall operate so that instability, uncontrolled separation, or cascading outages will not occur as a result of the? - ANS-Most severe single contingency N-1 A 230 kV transmission line is energized at 230 kV and is 100 miles long what is the approximate line charging contribution of this transmission line? - ANS-30 MVAR 230 kV= 1/3 MVAR per mile When a 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 TOP shall take corrective actions necessary to prevent voltage Collabs when reactive resources are insufficient including - ANS-Shedding firm load There is a SPS/RAS system out of service for maintenance and you're balancing area what actions do you take? - ANS-Operate within the system limits that the SPS/RAS is designed to protect against A bus with a closed breaker and then open-end breaker. Draw a line of the voltage profile - ANS-Close to open Voltage profile will increase when getting closer to the open breaker If a balancing authority has a 500 MW spinning reserves and of that, 300 MW are regulating reserves by definition NERC requires the regulating reserves must be? - ANS-Online, and automatic generation control AGC responsive What is the approximate and the MVAR/Mile For a 345 kV overhead line? - ANS-3/4 or 4 The most severe single contingency for your balancing authority area is 850 MW. A defined disturbance for DCS reporting would be equal to how many MW? - ANS-Most severe single contingency is computed using 80% of given MW 680MW A simple power system is composed of three transmission lines that connect the generation area to the load area. Three transmission lines are the same length but each line has a different impedance. Line 1 is 30 ohms, line 2 is 40 ohms, and line 3 at 60 ohms. The operating security limit of each line is 500 MW. If 1000 MW is flowing from generation to load what will the flow be online number two if the line 1 trips? Or line to violate its operating security limit? - ANS-Yes, 600 MW Of the following, which would be the best indicator for voltage collapse prone conditions? - ANS-Low reactive power reserves Pseudo-Tie is entered into what proportion of the balancing authorities tie line bias ACE equation - ANS-Actual interchange The initial interconnection time error is zero seconds. The interconnection then experiences four hours of 60.02 hurts and then three hours of 59.98 Hz frequency. What is the accumulated time error? - ANS-1.2 seconds per hour, over frequency is a positive value so 1.24 = 4.8, under frequency is a negative value 1.23 = -3.6 A transmission operator she'll have responsibility and clear decision-making authority to? - ANS-Alleviate operating emergencies A contingency results in the exceedance of an IROL. What could be the result if the IROL is allowed to be exceeded longer than Tv? - ANS-Interruption of power to a large part of the BES Frequency shows a disturbance then from point B to point C we see a slight increase. What could be happening? - ANS-Automatic governor response (AGR) A generator delivers its power to a multi-line transmission system. Of the multiple lines connected to the generator bus, line X absorbs 25% of the generator output is line X as a transfer limit of 200 MW what is the maximum output of the generator? - ANS-800 MW .25/200 = 1/x cross multiply Each balancing authority and transmission operator shall coordinate it's seasonal planning and operations with? - ANS-Neighboring BA, TOP, and RC When an IROL or SOL violation occurs, are responsible for responding to the IROL and SOL violations. - ANS-The transmission operators contributing to the violations and those affected by the violation What type of HVDC system has two conductors, one energized with a positive voltage and one with a negative voltage? - ANS-Bipolar Which of the following would be an example of "supplementary excitation control “equipment? - ANS-Power system stabilizer The mega white loading on a transmission line is at the point where the natural MVAR production of the line matches the lines MVAR usage. This MW loading point is called the? - ANS-Serge impedance loading (SIL) Load increases or decreases according to the increase or decrease in frequency. For every 1% change in frequency, load will change approximately. percent in the same direction. - ANS-2 A transmission line conductor is rated at 180 MVA, the line side current transformer is rated at 160 MVA and the bus is rated at 200 MVA. What is the MVA limit for the transmission line? - ANS-160 MVA If frequency, voltage, and phase angle difference are too large to permit breaker closing, a system operator should first consider? - ANS-Re-dispatching generation Station A bus is connected to station B bus by 230 kV transmission line. All stations have 100 MVAR shunt capacitor bank off-line. The SOL on this line is 350 MVA. The system operator is made aware that the line flows are 345 MW from station A to station B and 100 MVAR From station B to station A. The system operator should return the transmission line to its operating limit by? - ANS-Placing the capacitor bank online at Station A.A good way to think of this is that whichever direction is absorbing or taking in MVAR will need to be turned on. During extreme low load conditions, what are the primary system conditions a system operator typically works to alleviate? - ANS-High-voltage and over generation Which of the following actions is used to prevent a voltage collapse due to a reactive power deficiency? - ANS-Implement load reduction A reactor is rated at 100 MVAR nominal and is operating at a voltage of 90% how many MVAR is it absorbing from the system? - ANS-(V actual/V nominal) “2 ) x MVAR 81 MVAR Reactive resources are used to - ANS-Maintain acceptable voltage levels When | system is on the verge of voltage collapse and nothing else can be done to alleviate the problem operating personnel should? - ANS-Shed Firm load To be effective, reactive resources should be? - ANS-Located close to load areas If the line is loaded above its SIL, how does that affect the line and the voltage? - ANS- The line becomes more inductive and the voltage drops If the line is below it SIL, how does that affect the line voltage? - ANS-The line becomes more capacitive and the voltage raises. The value of MVAR, MW, MVA, Ampere, Hz and volts that satisfies the most limiting of the prescribed operating criteria for a specified system configuration to ensure operation within acceptable reliability criteria is called? - ANS-System Operating Limit (SOL) A system operator is attempting to synchronize two systems together in preparation of supplying customer load. The synchroscope it not moving. A system operator should first? - ANS-Adjust generation to verify the synchroscope is working Which condition is likely to lead to potential voltage collapse - ANS-Insufficient dynamic reactive resources Several SCADA Alarms indicate a disturbance in area B. They are for transmission lines connecting area A the area B which have become heavily loaded due to the disturbance. One of the lines above it's SOL. Reid dispatching of generation has no effect on line flows. As the operator, which answer best applies to the situation? - ANS- There is a possible separation or island in an area B Which of the following device’s primary purpose is to assist with the damping of power system oscillations? - ANS-Power system Stabilizer Generators have the ability to be used as voltage control devices. If a generator raises its VAR output, the system operator should expect the system voltage to? - ANS- Increase Each BA must have which of the following metering installed on their tie-line with other BAs? - ANS-MW and MWh Given normal operation conditions, why should AGC equipment remain in service? - ANS-To regulate ties Two or more BAs can join a RSG. Which of the following is a responsibility of an RSG? - ANS-Comply with the DCS as if it were a single BA If an Interchange Transaction is implemented to replace an unexpected generation Loss, no Tag is required if the Interchange Transaction lasts less than? - ANS-60 min Assume a TLR procedure has been implemented and Interchange Transactions have been curtailed. Assume further that the Operating Security Limits violation has been removed and some Interchange Transactions can be resumed. Which Interchange Transactions should if possible be re-established? - ANS-Those with the highest Transmission Service Priority BAA sells 100 MW to another BA. The ramp begins at the top of the hour and is ramped for 10 min. How much energy is actually transferred within the first clock hour? - ANS-92 MWh Operating authorities have the responsibility and the authority to take actions necessary to ensure reliable system operation within their operating areas. This could include all except which of the following? - ANS-Selling power to purchasers will to pay higher than current bid price Which of the following will contribute favorably to a BA's CPS1 score? - ANS-A negative ACE when frequency is above schedule A 230/115 kV transformer is rated at 100 MVA and has 80 MW entering the primary side. What would you expect the real power output to be on the secondary side? - ANS- 80 MW Several SCADA alarms indicate a disturbance in area B. There are four transmission lines connecting area A to area B which have become heavily loaded due to the disturbance. One of the lines is above SOL. Re-dispatching of generation has no effect on the line flows. As the operator, which answer best applies to this situation? - ANS- There is a possible separation or islanding in area B Of the following reactive reserve sources, which would fall into the static reactive reserve category? - ANS-Static VAR compensator in automatic mode The complete interchange Transaction Tag must be provided to all of the following except? - ANS-NERC RE personal Can a synchronous machine have a negative torque angle? What does this mean? - ANS-Yes, the machine is absorbing active power A pseudo-tie is entered into what proportion of a BAs tie-line ACE equation? - ANS- Actual Interchange Assume a 345/115 kV auto-transformer has NLTC on its high side winding with a range of +/- 5%. If the NLTC is initially at its neutral position, what would happen to the low side voltage if the high side tap were reduced by 5? - ANS-Rise by 5% Which BA is responsible for initiating the implementation of each Interchange Transaction as tagged? - ANS-The Sink BA The Source BA and Sink BA shall evaluate information for Arranged Interchange. Which data must be included in that assessment? - ANS-Energy Profile, Ramp and Schedule Path Voltage is high in an area due to off-peak demand. There are several lightly loaded high voltage transmission lines going to radial loads. All capacitor banks are out of service. Generators still have reactive reserves both leading and lagging. What should be done first to lower the voltage? - ANS-Use generators to absorb VARs A BAwith a bias setting of -200MW/0.1Hz changed Nis by +40MW as their part of a time error correction. The BA system operator decides instead of changing their Nls they will change their Fs value. The Fs value would be what? - ANS-60.02 Hz Unless agreed to by all involved Ba, the normal ramp duration for an interchange Schedule between the Eastern and TRE Interconnections is? - ANS-10 min All involved Ba, the normal ramp duration for an interchange Schedule between the Western and TRE Interconnections is? - ANS-20 min A certain dynamic schedule is tagged for an average flow of 100 MW. By what minimum amount would this schedule have to change before the Tag must be updated? - ANS-26 MW If in the course of operations during emergency conditions it becomes necessary to implement a voltage reduction, where should the voltage reduction take place? - ANS- On the distribution system Each TOP, TO, and DOP shall provide hours of system restoration training every calendar years to their field switching personnel identified as performing unique tasks associated with the TOPs restoration plan that are outside of their normal tasks. - ANS-2 hours, 2 calendar years During a system restoration, a system operator is receiving high MVAR and MVA alarms from the 345 kV system. What is the best way to bring the system back to an acceptable condition? - ANS-Energize shunt reactors Assume you are TOP. Further assume that you have both manually controlled shunt capacitors and automatically controlled generator MVAR available to use. Which type of MVAR resource would you utilize first and why? - ANS-Shunt capacitors to increase generator dynamic reactive reserve A power system has ten units on AGC. The units have different capacities and droop settings. The biggest adjustments in MW output in response to frequency disturbance will be provided by units that have? - ANS-Large capacity and small droop setting You are a BA; you anticipate a capacity shortage as your system moves into the day’s peak load hours. You should immediately? - ANS-Inform all affected systems During operating emergencies, plans should be in place to ensure adequate supplies of fuel, including: - ANS-Optimize the operation of generating plants, do fuel switching at plants where shortages may occur, request exemptions from environmental constraints A 500 MW generator trips in a BA to external to your BA. Which of the following responses would you expect to see in your Area? - ANS-Positive Net Actual Interchange deviation There are several AGC modes available to most BA. A BA that is operating asynchronously should switch its AGC mode to? - ANS-Flat Frequency mode Real-Time Tags for interchange transactions of less than an hour from Ramp start time must be submitted? - ANS-10 min Real-Time Tags for interchange transactions 1-4 hours from Ramp start time must be submitted? - ANS-20 min Real-Time Tags for interchange transactions 4 hours + from Ramp start time must be submitted? - ANS-120 min 2 hrs Your system load is 4000 MW. An event report to NERC is required if you shed load how many MWs to maintain continuity of the BES? - ANS-> 100 MW The transmission path used to connect a black start resource to the next generator to start is called - ANS-Cranking path If a BA does not meet the DCS during a given quarter, what category of reserve must be increased for the subsequent quarter? - ANS-Contingency Reserve Which type of protection relay utilizes CTs to ensure a normal conditions balance between current inflow and outflow? - ANS-Differential Of the following possibilities which is a GMD most likely to cause? - ANS-Transformer Overheating A tool is used to ensure the power system can respond within acceptable limits N-1 conditions - ANS-Contingency Analysis Which factor accounts for the amount of transfer capability reserved by a Load Serving Entity to ensure access to generation from the interconnection systems to meat generation reliability requirements? - ANS-Capacity benefit Margin CBM Assume EEA 3 is declared & the deficient BA is in need of additional ATC. From the allocations could the RC seek to obtain the ATC? - ANS-Capacity Benefit Margin Assume you are monitoring ACE and frequency as the peak load hour approaches. Frequency is gradually decreasing and then your net actual interchange swings from out to in. Frequency and Nla then become erratic. Frequency is oscillating about its 60 Hz target. This combination of event best indicates - ANS-Instability within the power system In an islanded or isolated condition, typically the first thing you would do is? - ANS- Determine the extent and condition of the isolated area Which BA is responsible for implementation of each Interchange Transaction as Tagged? - ANS-Sink BA A major TO line has been scheduled out for maintenance. Other outages have occurred and the load will be greater than originally expected. The system operator should: - ANS-Preform a load flow study prior to allowing the previously scheduled Cold load pick up can involve current flows of up to what maximum levels? - ANS-10 or more times normal Two methods NERC recommends be used to verify a systems power system restoration plan: - ANS-Actual testing in the power system, Simulation testing with computer models. During which level of an EEA is the deficient entity for which the RC initiated the EEA first called an Energy Deficient Entity? - ANS-2 Why is location of transmission reactive resource reserves important? - ANS-Reactive power is difficult to transmit through high Impedance BA A has the following schedules implemented. What is the BAs' Nls and are they an exporting or an importing BA? Import BA B 100MW Import BA C 200 MW Export BA D 800 MW - ANS-500 export A certain dynamic schedule is tagged for an average flow of 100 MW. By what min amount would this schedule have to change before the tag must be updated? - ANS-26 MW If a capacitor bank is removed from service, what is the immediate effect will there be on the voltage? - ANS-Decrease If system frequency were to run at 60.02 Hz for two hours how much positive time error would occur? - ANS-2.4 seconds The Interconnection frequency suddenly drops from 60Hz to 59.94Hz while your BA ACE is zero. The Low frequency condition exists 15 min later. Assuming you have the following options which would you take? - ANS-Make known your ability to provide emergency assistance: Act bilaterally to raise frequency What percentage of Contingency Reserve does NERC require be the frequency responsive type of Spinning Reserve? - ANS-NO requirement There are several AGC modes available to most BA. A BA that is operating asynchronously should switch its AGC mode to - ANS-Flat Frequency Control (Constant) Overlapping regulation service is a method of providing - in which the providing BA incorporates all of the other BA tie-lines frequency response, and schedules into its own AGC/ACE equation. - ANS-Regulation Service BA A has 10 generators total capacity of 1SOOMW 5 have the capacity of 100 MW and 5 are at 200 MW. Generator at 180 MW loaded trips off. Is this a DCS event and if so how long does the BA have to return ACE to DCS limits? - ANS-yes, 15 min The initial response to a frequency deviation is due to which of the following: - ANS- Load/Frequency response/Governor Action When generation or transmission equipment must be removed from service the GOP BA and TOP must: - ANS-Coordinate with the RC, Ensure the reliability impact of the outage is evaluated A dynamic schedule is tagged for 25 MW. By what min % amount would this flow have to change to change before the Tag must be updated? - ANS-More than 100% When energizing transmission lines during power system reconstruction which of the following factors do you most need to consider? - ANS-Natural Capacitance When attempting to synchronize two Islands with different Hz it is normally advisable to: - ANS-Direct the smaller island to change speed How long would it take for a 60Hz voltage wave to complete 1/4 of its cycle? - ANS- 1/240 To avoid a high over voltage at the open end of a transmission line the switching sequence is arranged so that some load is attached to the otherwise open-end Which type of load would best reduce this Ferranti over voltage? - ANS-Lagging Power factor load A TOP restoration plan must describe the restoration of the power system up to the point at which - ANS-The next load to be restored is done for the sake of the customer A BA is experiencing low voltage in the northeast region. A 50 MVA generator in that area is loaded at 50 MWs. What action could a System Operator take to increase the voltage in that area? - ANS-Decrease real power and increase reactive power In the initial stage of a restoration condition high transmission system voltage problems are more likely than low transmission system voltage problems - ANS-Excessive MVAR supply from the energization of the transmission lines A system operator has exhausted all available resources and re-dispatched options. System voltage continues to decline. What should the system operator do next? - ANS- Shed load in the low voltage area A GDM is predicted to occur tomorrow which parts of the system are most likely to experience problems - ANS-Wye connected transformers During the initial stages of the system restoration process, load pick-ups should be limited to of the total synchronized generation. - ANS-5% will be sold as a non-firm transmission product during EEA2 - ANS-Capacity Benefit Margin A thermal generator has an emergency power source. Which two items below would typically power from this emergency power source? - ANS-Turning Gear, Lube oil Pump Transmission lines are protected by the transfer trip, carrier, and other types of pilot relay schemes. Pilot relay schemes are necessary for what reason? - ANS-Pilot relays allow instantaneous tripping for faults within 10%-20% of the line distance from the remote terminal with primary protection While adjusting the tap changer on a large power transformer's protective relays operate. The most likely relay to operate would be? - ANS-Differential Load rejection schemes are a form of Remedial Action Schemes RAS. In a load rejection scheme, the term load refers to the: - ANS-Generator MW output The purpose of the CT and PT is to the high voltage power source to the low voltage relays. - ANS-Step down High speed transmission protection is a benefit to angle stability because: - ANS-Fault duration is reduced, accelerating time is reduced, angle spread is reduced e What type of relay uses a combination of CT measurements and PT measurements and operates when the ration of the PT measurements to CT measurements is below a certain limit for a given period of time? - ANS-Distance Relay