NACE CP2 Exam Questions with Verified Answers, Exams of Advanced Education

Download NACE CP2 Exam Questions with Verified Answers and more Exams Advanced Education in PDF only on Docsity! NACE (National Association Of Corrosion Engineers) CP2 EXAM Questions With 100% Correct Answers | Verified | Updated 2023-2024 NACE 2008 Student Manual! START OF CHAPTER 1 Corrosion is an electrochemical process involving A) flow of protons and electrons B) flow of neutrons and ions C) flow of protons and ions D) flow of electrons and ions E) flow of resistance and resistivity d Metal loss or corrosion occurs at the A) cathode B) anode C) electronic path D) metallic path b What are the four parts of the corrosion cell A) anode, resistor, electrolyte, metallic path B) anode, cathode, electron, electronic path C) anode, cathode, electrolyte, metallic path c True or False (t or f): Ions exist only in the electrolyte? t Electrons flow in a corrosion cell by which of the following paths? A) anode to cathode via electrolyte B) cathode to anode via electronic path C) anode to cathode via electronic path c At the cathodic surface in a corrosion cell, the electrons from the ____ meet ____ ions from the solution. A) cathode, hydrogen B) cathode, OH- C) anode, hydrogen D) anode, OH- c Oxidation of the metal occurs at the ____ surfaces and reduction of ____ ions occurs at the ____. A) anodic, hydrogen, cathodes B) cathode, OH-, anodic C) anodic, OH-, cathodes D) cathode, anodic, electrolyte E) cathode, hydrogen, electrolyte a True or false Is oxidation necessarily associated with oxygen? f _____ is the measure of the electrochemical difference between two electrodes in an electrolyte A) current B) resistance C) error D) ohms E) ohms-cm F) voltage f The ________ represents the reversible work to move a unit charge from the electrode surface through the solution to the reference electrode A) current potential a If a metallic path connects two electrodes inside an electrolyte, the ____ difference will cause a ____ to flow between them A) current, voltage B) resistance, current C) resistance, voltage D) voltage, current E) current, resistance d The more useful method of organizing metals in order of their tendency to corrode is _____ A) emf series B) pgp series C) nuclear series D) electron series E) galvanic series e The ____ expresses the exact electromotive force of a cell in terms of the activities of products and reactants of the cell A) Ernest Equation B) Faraday Equation C) Ohm's Law Equation D) Nernst Equation E) Uniform Equation d Given the Nernst Equation, using the Valence of Common Metals Table, and using the partial Standard emf Series of Metals solve: What is the potential of zinc in a 0.01 molar zinc chloride solution at 25C? A) -0.892V B) -0.287V C) -0.827V D) -0.297V E) -0.889V c E= -0.763 + (0.059/2) log (0.71 0.01/1) = -0.827V Standard conditions for pure metals in the emf series are based on one unit activity of metal ions in the electrolyte at ___ C with no impurities in the metal or electrolyte and with reference to a standard ____ electrode. A) 25, hydrogen B) 35, hydrogen C) 25, CSE D) 35, CSE E) 25, SSC F) 35, SSC a The ____ the concentration of metal ions in the electrolyte, the ____ the metal. A) lower, less active B) higher, less active C) lower, more active D) higher, less active b In reference to the temperature in a corrosion cell, in most cases, electrode at the _____ temperature becomes the ____ A) lower, anode B) higher, cathode C) lower, cathode D) higher, anode d During metal fabrication of structures, highly stressed areas of a metal will tend to be at ____ energy levels, thus more ____ than less stressed areas A) higher, active B) lower, active C) higher, inactive D) lower, inactive a True or False (t or f): Corrosion cells may form because of differences in the electrolyte t ____ cells are responsible for much of the corrosion that take place in soils, particularly in bare or poorly coated pipe A) concentration B) steady state C) carbon D) dynamic E) telluric a In many cases in naturally occurring soils, a portion of pipe lying in the more _____ soil is the ____ and in the less ____soil is the ___. A) inductive, anode / inductive, cathode B) inductive, cathode / inductive, anode C) conductive, anode / conductive, cathode D) conductive, cathode /conductive, anode c The two most common types of concentration cells involved in promoting corrosion are ____ and ____. A) oxygen, nonmettalic ion B) oxygen, calcium C) lack of oxygen, metal ion D) oxygen, metal ion d What is the most common of the cathodic depolarizers, that can maintain and promote a cathodic reaction? A) CO2 B) oxygen C) carbon f Which reference electrode is considered a primary reference electrode because it is used to determine the potential of other secondary reference electrodes that are better suited for field use? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE e Most common used reference electrode for measuring potentials of underground structures? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE a True or false (t or f) The potential of a reference electrode in the sun can decrease from 10 to 50mV versus an electrode kept in the dark? t Which reference electrode is mostly commonly used in seawater? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE b Which reference electrode is mostly commonly used in concrete structures? A) CSE B) Ag/AgCI C) Calomel D) Zinc E) SHE b Which of the following is primarily a laboratory electrode? A) CSE B) Ag/AgCI C) Calomel D) Zinc c When doing a structure to electrolyte potential , the structure is connected via the _____ terminal and the reference is connected via the _____ terminal A) negative , positive B) positive, negative b A potential of -0.810Vcse converted to Calomel (SCE) A) +0.306 sce B) -0.750 sce C) -0.735 sce c A potential of -0.810Vcse converted to Ag/AgCI (SSC) A) +0.306 ssc B) -0.735 ssc C) -0.750 ssc c A potential of -0.810Vcse converted to Zinc (ZRE) A) +0.306 zre B) -0.735 zre C) -0.750 zre a True or False (t or f) The potential of a STATIONARY reference electrode should be checked from time to time with a portable reference electrode that is known to be accurate under "no current" conditions. t As current is impressed on a metal over time, where does polarization occur? A) at the anode and the cathode B) at the anode C) at the cathode a Polarization _____ the potential difference between the anode and the cathode and by Ohm's Law, the current ___ and the corrosion rate ____ until an equilibrium is reached A) lowers, drops, decreases B) increases, increases, decreases C) lowers, increases, decreases D) lowers, drops, decreases d Depolarizers include: I dissolved oxygen II microbiological activity III water flow A) only I B) only II C) I and II D) I, II , III d The name for the current that exists during the steady state of polarization is called the _____ of the system A) telluric current B) dynamic current C) corrosion current D) mixed potential current E) closed current c The potential normally measured between the polarized cathode potential and the polarized anode potential A) mixed potential structure A) larger, larger B) less, larger C) greater, smaller D) smaller, smaller E) greater, larger e True or False (t or f) A small anode and a large cathode is desirable f A(n) ____ in temperature has a tendency to ____ chemical reactions, which _____ the electrodes and _____ current A) increase, increase, depolarizes, increases B) increase, increase, depolarizes, decrease C) decrease, decrease, polarize, increase D) decrease, increase, polarize, decrease a A(n) ____ in temperature results in a(n) ____ in polarization A) increase, decrease B) increase, increase C) decrease, increase D) decrease, decrease c ____ movement results in a ____ in polarization and a(n) _____ in current A) decreased, decrease, decrease B) decreased, increase, decrease C) increased, increase, decrease D) increased, decrease, decrease E) increased, increase, increase d A(n) _____ in the metal ion concentration of the anode metal results in a(n) ____ in polarization of the anode and a(n) ____ in current A) increase, decrease, decrease B) decrease, decrease, decrease C) decrease, increase, decrease D) increase, increase, decrease E) decrease, decrease, increase e Polarization of the cathode can be affected by the concentration of cathodic reactants, such as _____ or _____ ions A) CO2, OH- B) oxygen, OH- C) carbon, OH- D) oxygen, hydrogen d In regards to cathodic reactants, a(n) _____ in the concentration of either of the reactants of oxygen or hydrogen will _____ polarization of the cathode and _____ current and vice versa A) increase, decrease, decrease B) decrease, decrease, decrease C) increase, decrease, increase D) increase, increase, decrease E) decrease, decrease, increase c Passivity can be defined as the A) gain of chemical reactivity B) polarization of chemical reactivity C) loss of chemical reactivity D) depolarization of molecular reactivity E) polarization of molecular reactivity c The ____ region is when a slight increase in corrosion potential causes the corrosion current to increase A) transpassive B) passive C) nonpassive D) active d The ____ region is when the corrosion potential increases to a certain point, however, the corrosion current suddenly decreases and remain essentially constant A) transpassive B) passive C) nonpassive D) active b The ____ region occurs if the potential is increased sufficiently thus current again increases A) transpassive B) passive C) nonpassive D) active a For the active (or nonpassivating) metal, as corrosion potential _____, corrosion current ____, more or less logarithmically (or linearly on a semi- log graph). A) increases, increases B) decreases, decreases C) increases, decreases D) decreases, increases a This type of film which forms naturally on most metals when they are exposed to the air, can provide substantial protection against further attack by many environments A) ore B) oxide C) reductant D) selimum b Type of corrosion with an even loss of metal over the entire area or a large area of the structure A) Galvanic attack B) intergranular attack C) selective leaching D) velocity phenomena E) pitting F) crevice corrosion G) uniform attack d In general, hydrogen is generated in neutral environments at - ____ mV CSE A) 1,000 B) 1,044 C) 1,500 D) 1,200 b For aluminum, the polarized potential must be kept below - _____ mV CSE to avoid alkali corrosion A) 1,000 B) 1,044 C) 1,500 D) 1,200 d For titanium, the maximum potential is ____ mV ssc to prevent hydriding A) 800 B) 700 C) 1,500 D) 1,200 b For prestressed concrete, polarized potentials more negative than -____ mV should be avoided A) 1,000 B) 1,044 C) 1,500 D) 1,200 a The cracking of a metal under an applied tensile stress in the presence of a corrosive environment A) stress corrosion cracking B) intergranular attack C) selective leaching D) velocity phenomena E) pitting a Stress Corrosion Cracking occurs in a narrow potential range of ______ at a pH between ______ , and is more likely at ____ temperatures A) -525 to -725, 5 and 7, more B) -625 to -825, 7 and 9.5, less C) -525 to -725, 8 and 10.5, more D) -625 to 700, 8 and 10.5, less c True or False (t or f) MIC exist under non anaerobic conditions (presence of great oxygen) f In relation to MIC, consumption of _____ at the structure surface _____ the steel at cathodic areas and permits more rapid consumption of the metal by galvanic corrosion cells A) hydrogen, polarizes B) hydrogen, depolarizes C) OH-, polarizes D) OH-, depolarizes END OF CHAPTER 1 b START OF CHAPTER2: Corrosion of the metal will cease once the applied cathodic protection current _______ the corrosion current. A) equals B) equals or exceeds C) falls below b As the potentials of the ___ sites polarize toward the potentials of the ____ sites, corrosion current is ____. A) anodic, cathodic, increase B) cathodic, anodic, reduced C) cathodic, anodic, increase D) anodic, cathodic, decrease b Polarization occurs in a step-like manner with the more ____ or ____ sites polarizing first. A) positive, anodic B) positive, cathodic C) negative, anodic D) negative, cathodic b To mitigate corrosion, all existing cathode sites must be electronegatively polarized to a potential ____ to the open circuit potential of the most ___ ____ potential existing on the structure. A) equal, inactive, cathode B) unequal, active, anode C) unequal, inactive, cathode D) equal, active, anode d Polarization of the ____ to the ____ potential of the anodes is the true criterion for eliminating corrosion. A) cathodes, closed circuit B) anodes, closed circuit C) cathodes, open circuit D) anodes, open circuit c Bare Pipe: What is the current required to protect an uncoated 30.48 cm (12 in.) diameter steel pipeline 1,524 m (5,000 ft) in length that is buried in soil with a resistivity of 10,000 Ω-cm? Assume experience has shown that adequate levels of cathodic protection can be achieved from 10.76 mA/m 2 (1 mA/ ft 2 ) of bare surface area. A) 16.8A B) 15.7A As ionization _____, the electrolyte's conductivity _____, which _____ corrosion current and the amount of cathodic protection current required for adequate protection. A) increases, increases, increases B) increases, decreases, decreases C) increases, decreases, increases D) decreases, increases, decreases E) decreases, decreases, decreases a Oxygen or other oxidizers ____ the current requirements as a result of flattening the cathodic polarization slope A) increase B) decrease a True or False (t or f) structures in well aerated soils, such as sand and gravel, require more cathodic protection current than structures surrounded by relatively deaerated soils, such as clay. t A(n) _____ in the relative movement between the electrolyte and the structure causes a(n) _____ in current requirement A) increase, decrease B) increase, increase C) decrease, increase D) decrease, decrease b True or False (t or f) a ship under way requires less cathodic protection current than a ship at rest f To reduce the residual corrosion current to zero, cathodic protection current must be _______ A) disproportionately increased B) disproportionately decreased C) proportionately increased D) proportionately decreased a The relationship between applied cathodic protection current and corrosion rate is ____ A) proportional B) disproportional C) logarithmic c In regards to amphoteric metals: The formation of ____ ions at the cathode causes the pH of the electrolyte next to the cathode to become ____. A) hydroxyl, aciditic B) hydrogen, aciditic C) hydroxyl, aciditic D) hydroxyl, alkaline d For pipeline coatings, polarized potential values more negative than ____ mV CSE should be avoided. A) -1000 B) -1500 C) -1200 D) -850 c Control of External Corrosion on Underground or Submerged Metallic Piping Systems A) SP0170 B) SP0169 C) SP0007 D)SP0175 b True or False (t or f) The potential of interest when determining adequate cathodic protection is the polarized potential across the structure/electrolyte interface t Figure 2.15 E true = A) Structure to electrolyte potential B) Reference-to-earth resistance C) Pipe-to-earth resistance a Figure 2.15 R r,e = A) Structure to electrolyte potential B) Reference-to-earth resistance C) Pipe-to-earth resistance b Figure 2.15 R p,e = A) Structure to electrolyte potential B) Reference-to-earth resistance C) Pipe-to-earth resistance c Figure 2.15 (a) Electrical Schematic of the Structure to Electrolyte Measurement Circuit A) Vm = Rm/Rt * Etrue B) Vm= Rt/Rm * Etrue C) Vm = Rt/Etrue * Rm D) Vm = Rm/Etrue *Rm a Do you want high or low impedance on your internal circuit of your meter? A) low B) high b The IR drop across the electrolyte can be reduced to near zero by placing the reference electrode ____ the structure coating holiday or by ____ the current flow B) increasing, polarized C) decreasing, depolarized D) increasing, polarized b In relation to E log I: True or False: The time interval between measurements and the current increments should be kept as consistent as possible to eliminate distortions due to the change of polarization with time t In relation to E log I: The range of test current must be ___ than the estimated current required for protection A) greater B) less a In relation to E log I: The measured potential must be corrected for ____ error to obtain a polarized potential (Instant Off). A) IR drop B) current drop C) signal drop a Figure 2.17 _____ is considered as an adequate potential for cathodic protection under the E log I method. A) Icp B) Ecorr C) Tafel Slope D) Ecp END OF CHAPTER 2 d START OF CHAPTER 3 True or false (t or f) Pure forms of anode metals are best because they do not undergo too much "self corrosion?" f The pure forms of the metals are often not suitable as anodes because they undergo too much "self corrosion" in the environment and do not stay active. A Magnesium Standard Alloy ______ A) is used for use in low-resistivity soils and water B) provides a higher driving voltage than the standard alloy a A Magnesium High-Potential Alloy A) is used for use in low-resistivity soils and water B) provides a higher driving voltage than the standard alloy b Zinc anode MIL-A-18001 or ASTM B418 Type I is _______ A) for use in low-resistivity soils and water B) provides a higher driving voltage than the standard alloy b Zinc anode MIL-A-18001 or ASTM B418 Type II is _______ A) high purity for underground and fresh water use B) for salt water and brackish water use a Aluminum ally anodes are used primarily in ______ applications A) dry soil B) fresh water C) seawater c True or False (t or f) Aluminum anodes are not used in fresh water, except as impressed current anodes t Galvalum I A) contains zinc and mercury for use in saline mud B) contains zinc and mercury for use in seawater C) contains zinc and indium for use in seawater, brackish water, and saline mud b Galvalum II A) contains zinc and mercury for use in saline mud B) contains zinc and mercury for use in seawater C) contains zinc and indium for use in seawater, brackish water, and saline mud a Galvalum III A) contains zinc and mercury for use in saline mud B) contains zinc and mercury for use in seawater C) contains zinc and indium for use in seawater, brackish water, and saline mud c True or False (t or f) The consumption of any metal is directly proportional to the amount of current discharged from its surface t Anode efficiency is the ratio of _____ producing useful cathodic protection ____ to the total metal consumed. A) metal added, current B) voltage, current b ______ and _____ alloys have been used as impressed current anodes on reinforced concrete structures. A) Magnetite, Mixed-Metal Oxide B) Copper, Galvalum C) Thermal sprayed zinc, aluminum c It is used in seawater, brackish water, fresh water, and high-resistivity soil A) Magnesium B) Zinc C) Graphite D) Aluminum E) Galvalum F) Magnetite f The purpose of anode backfill material is I reduce the resistivity II extend the anode surface area III decrease the amount of current the anode can discharge IV reduce consumption of the anode A) I, II B) I, II, III, IV C) II, III, IV D) I, II, IV d True or False (t or f) The resistance of carbon backfill is not dependent on how well it is compacted f In regards to anode backfill: The ____ the degree of compaction, the ____ the resistance A) lower, higher B) higher, higher C) higher, lower D) lower, lower c In regards to anode backfill: ____ grade coke is often used for ____ anode systems A) larger, hortizonal B) finer, deep C) finer, shallow D) larger, deep b True or false (t or f) Any exposed metal in an impressed current CP system is part of the anode. t Types of CP cables: This insulation is commonly used for direct burial cathodic protection installations for both anode and structure wiring A) HMWPE B) Halar C) Kynar a The primary reactions at the anode surface are: I metal oxidation II oxygen and chlorine evolution III chlorine generation A) only I B) I, II C) I, II, III c Gases in a deep anode system should be ____ A) vented B) non vented a Reactions at the anode produce an excess of ____ ions A) hydroxl B) chlorine C) carbon D) hydrogen d Hydrogen ions will _____ the environment immediately adjacent to the anode A) acidify B) alkalify a Anode configurations can be described as ____ or ____ A) distributed, nondistributed B) remote, unified C) distributed, remote c The anode gradients are ____ within a few feet of the anode. A) largest B) smallest a The term ____ refers to the point where further distance from the anode produces no further change in voltage gradient. A) distributed B) remote earth C) area of influence D) gradient area b A _____ configuration uses anodes located at relatively close intervals along the structure. A) distributed A rectifier converts the ___ power supply voltage to the required ___ voltage and then converts it to ___ A) DC, output, AC B) AC, input, DC C) AC, output, DC D) DC, input, DC E) DC, output, DC c True or false (t or f) Rectifiers are either supplied in ventilated cases or are immersed in transformer oil t _____ provides protection to the rectifier components from current surges or overload A) circuit breaker B) fuses C) panels D) shunt a In order to disconnect the AC when working on the face of the panel, the ___ most be off A) meters B) fuses C) panels D) circuit breaker d These breakers have a bimetallic element that carries current A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers b Circuit breaker is in the tripped position when it is in the ____ position A) up B) down C) left D) right E) center e This breaker is considered the most suitable for CP rectifiers A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers a The ______ consists of an iron core surrounded by a coil of wire A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers a It has a magnetic plate attached to the element to increase the speed in tripping the circuit A) magnetic breakers B) thermal breakers C) exothermic breakers D) thermal magnetic breakers d When it trips it causes the core to pull a trip lever towards it thus causing an open circuit A) exothermic breaker B) thermal breakers C) magnetic breaker D) thermal magnetic breakers c The purpose of a ____ is to either "step up" or "step down" a(n) ___ supply voltage A) transformer, AC B) circuit breaker, DC C) fuse, DC D) central processing unit, AC E) transformer, DC a The ratio of the ____ voltage to the induced _____ is in ______ to the windings in each coil A) primary DC voltage, secondary DC voltage, inproportiate B) primary AC voltage, secondary AC voltage, proportion C) primary DC voltage, secondary DC voltage, inproportiate b In regards to a transformer: The ______ is connected to the ____ supply and the alternating magnetic field ____ a(n) AC voltage in the _____ A) secondary winding, secondary AC voltage, induces, secondary winding B) primary winding, primary AC voltage, conducts, secondary winding C) primary winding, primary AC voltage, induces, secondary winding D) secondary winding, primary AC voltage, induces, secondary winding c Transformers use _____ A) induction B) conduction a If a transformer has no losses, what is the secondary voltage of a transformer being supplied with 115 V AC that has 400 turns on the primary and 100 turns on the secondary windings? A) 30Vac B) 28.75Vac C) 22.5Vac D) 32.75Vac b The _____ tap changes the ____ voltage A) primary, AC B) secondary, AC True or False (t or f) The positive potentials always transfer to output terminal O1, and the negative potentials transfer to output terminal O2. t In regards to rectifiers: Plates are arranged in "stacks," with the ___ and ____ of plates being determined by the ___ and ____ output capacity of the rectifier. A) weight, size, voltage, current B) number, size, voltage, current C) number, spacing, resistance, conductivity D) spacing, weight, resistance, current b Which of the diodes in a rectifier is more sensitive to current surges and can be quickly destroyed by any current overload A) silicon B) selenium a True or False (t or f) Silicon stacks are often called "self-healing" f selenium is "self-healing" _____ diodes consist of a wafer sliced from a pure single crystal of ____ A) silicon B) selenium _____ stacks can tolerate current overloads up to ten times rated capacity for a few minutes A) silicon B) selenium b Which is more efficient selenium or silicon diodes A) silicon B) selenium a Which of the rectifier diodes fail completely rather than slowly A) selenium stacks fail completely rather than slowly like silicon diodes B) silicon diodes fail completely rather than slowly like selenium stacks b _____ rectification can be achieved with ___ diodes in a ___ tap configuration A) half-wave, four, center B) full-wave, four, center C) half-wave, two, center D) full-wave, two, center d In regards to rectifiers: In the single phase circuit, ___ diode conducts during each AC cycle and produces a large ripple. A) one B) two C) four D) six a ______ supply current in a cyclic fashion A) Silicon -Controlled Rectifiers B) Pulse Rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers b ______ are sometimes added to provide additional control of the rectification process for some types of cathodic protection rectifiers. A) selenium-controlled rectifiers B) silicon-controlled rectifiers b Silicon-controlled rectifiers are _____ three-junction PN devices A) 2 B) 3 C) 4 D)6 b In regards to rectifiers: In order for the SCR to be forward biased and begin conducting, a ___ potential (V AC ) must be applied between ___ (P side) and ___ (N side), and a positive voltage pulse must also be applied between the ___ and the ____ (V GC ) as seen in the center A) negative, anode, cathode, bridge, cathode B) positive, cathode, anode, gate, cathode C) positive, anode, cathode, gate, cathode D) negative, anode, cathode, gate, cathode c In regards to rectifiers: At the instant the gate pulse is applied, the SCR fires and begins to conduct current from the ____ to the ____ A) anode, cathode B) cathode, anode a In regards to rectifiers: Regardless of the gate current, the SCR continues to ____ until the applied voltage (V AC ) goes to ____ and the current returns to ___ A) induct, zero, equal B) induct, zero, zero C) conduct, equal, zero D) conduct, zero, zero To improve efficiency and reduce ripple, manufacturers normally add filters to the output terminals t Rather than adjusting the output voltage level using a large, laminated steel core transformer, ______ control the DC output voltage level by producing a series of high frequency (typically 50 to 500 k Hz) DC pulses and adjusting the timing of DC pulses to produce the required output DC voltage level. A) Silicon -Controlled Rectifiers B) Pulse Rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers E) Constant Voltage rectifier d In regards to a Standard Transformer Rectifier, but the following in order from left to right: Rectifier AC Input Filter (if used) Low Frequency Transformer w/TAPs DC Output In regards to a Switching Mode Rectifier, put the following in order from left to right DC Output Primary Filter Transformer Secondary Filter Secondary Rectifier Sensing/Switching Circuit Primary Rectifier AC Input Solid State Switch In regards to a switching mode rectifier: The DC pulses are fed through a high frequency ____ to isolate the output. A) transformer B) primary filter C) secondary rectifier D) solid state switch a In regards to a switching mode rectifier: The _______ next converts the DC to high frequency DC pulses A) transformer B) primary filter C) secondary rectifier D) solid state switch d In regards to a switching mode rectifier: The _______ circuit provides feedback control to the _______ to control the "on" and "off" timing (pulse width) of the switch A) solid state switch, sensing / switch control B) secondary rectifier, primary filter C) solid state switch, secondary rectifier D) sensing/switch control, solid state switch d The primary advantages of a switching-mode rectifier over a standard transformer/ rectifier are I higher reliability due to number of components II Small size and weight III Prone to higher ripple IV High efficiency at low rated output A) only I B) I, II, IV C) II, IV D) I, II, III E) I, II, III, IV c In this type of rectifier, the output voltage is adjusted by changing the secondary transformer taps A) Silicon -Controlled Rectifiers B) Pulse Rectifier C) Thermoelectric rectifier D) Switch-mode rectifiers E) Constant Voltage rectifier F) Constant Current rectifier e True or false (t or f) In a switching mode rectifier: Repair of individual modules is easy and practical f it is NOT practical Adjustment of the output is a combination of varying the frequency and adjusting capacitors that in turn set the duty cycle with this type of rectifier A) Silicon -Controlled B) Pulse C) Thermoelectric D) Switch-mode b The primary use of pulse rectifiers is on _____ A) foreign lines B) mountainous areas C) well casings D) anode beds c The _____ rectifiers are usually adjusted by changing the transformer tap settings A) Silicon -Controlled B) Constant Current C) Thermoelectric D) Switch-mode E) Constant Voltage F) Pulse e In regards to rectifiers: The general procedure to change taps is to turn off rectifier, increase the ____ one setting making certain that the connections are tight, and turn on the rectifier checking ____output voltage A) Coarse tap, DC B) Fine tap, DC C) Coarse tap, AC D) Fine tap, AC b In regards to rectifiers: When the Fine taps have reached the _____, lower it to the first setting and increase the ____ one setting. A) minimum, fine tap B) maximum, coarse tap C) maximum, fine tap D) minimum, coarse tap b Potential control and constant current rectifiers are controlled using a______adjustment found on the controlling circuit board A) multimeter B) ammeter C) potentiometer D) ohm meter E) shunt c Thermoelectric Generators for CP use the ______ effect to generate potentials across a dissimilar metal junction A) Seebeck B) Hardlock C) Kirkhoff D) Ohms a In regards to solar energy: The conversion efficiencies for silicon-based photovoltaic cells are in the range of ____% A) 5 to 15 B) 10 to 20 C) 8 to 14 D) 20 to 25 c In regards to solar energy: What device ensures the battery bank is properly charged A) solar panels B) charge controller C) monitor D) CP regulator b Basic rectifier operational data includes I AC input voltage II AC output voltage III DC output voltage and DC output current IV Tap settings V cathode to structure resistance VI anode to structure resistance A) I, III, IV, V B) I, III, V C) I, III, IV, VI D) all c In regards to standard single-phase, manual adjustment type rectifiers: If there is no input power to the unit or an open circuit within the rectifier is indicated, this is an example of a(n) _______ problem A) Zero Current Output with Unchanged Voltage Output B) Significant Current Change with Unchanged Voltage C) Significant Changes in Both Voltage and Current Outputs D) Significant Changes in Both Voltage and Current Outputs E) Zero Current and Voltage Outputs e In regards to standard single-phase, manual adjustment type rectifiers: system additions, shorts to other underground structures, or major coating damage are signs of _____ problems A) Zero Current Output with Unchanged Voltage Output B) Significant Current Change with Unchanged Voltage C) Significant Changes in Both Voltage and Current Outputs D) Significant Changes in Both Voltage and Current Outputs b In regards to standard single-phase, manual adjustment type rectifiers: Open fuse in the output circuit, Faulty connections, An open positive or negative lead cable, Failed anodes A) Zero Current Output with Unchanged Voltage Output B) Significant Current Change with Unchanged Voltage C) Significant Changes in Both Voltage and Current Outputs D) Significant Changes in Both Voltage and Current Outputs a In regards to standard single-phase, manual adjustment type rectifiers: If AC voltage is present at the ___ terminals, an ___ circuit exists within the ___. A) output, closed, anode If the voltage and current outputs are approximately one-half of the normal values, the most probable cause is partial failure of ____ , however if the _____ are found to be operating properly, the ____ should be investigated for possible winding to winding shorts A) rectifier case, transformer B) transformer, rectifier stacks, rectifier case C) rectifier stacks, rectifier stacks , transformer c True or False, in regards to rectifier troubleshooting: If the cathode-to-structure resistance is normal, then the problem is with the rectifier f If the ANODE-to-structure resistance is normal, then the problem is with the rectifier Which conditions can cause internal short circuits I Failed diodes II contact in transformer windings III Contact between positive circuit and the rectifier cabinet or negative circuit IV Spark-gap type lightning arrestors failed in the shorted condition A) I, II, III B) I, II C) II, III, IV D) all d True or false: Internal short circuits can occur due to any metallic contact between the positive and negative circuits f EXTERNAL short circuits can occur due to any metallic contact between the positive and negative circuits True or false: Inadvertent contact between the anode or its low resistivity backfill and the structure is the most common type of external short circuit t When confronted with a possible short circuit: A) connect all external positive and negative cables at the rectifier before re-energizing the rectifier B) disconnect all external positive and negative cables at the rectifier before re-energizing the rectifier b If the rectifier operates normally upon re-energizing, then the short is ____ to the unit, providing the short reappears when the cables are _____ A) internal, reconnected B) external, disconnected C) internal, disconnected D) external, reconnected d If the open circuit is ___, then the voltage will appear across the internal component with open circuit. A) external B) internal b True or false All rectifiers units can not be operated in the shorted condition when on the lowest AC tap setting f SOME rectifier units can be operated in the shorted condition when on the lowest AC tap setting In regards to rectifiers: The open circuit condition is characterized by ____ A) increase current output B) decreased current output C) increased voltage output D) zero current output d Which of the following is NOT a common cause of internal open circuits I failed diode II broken cables III open connections IV blown fuses A) I, II, IV B) II, III, IV C) I, II, III, IV D) all are a common cause of internal open circuits d True or false External open circuits generally do not involve broken or corroded cables f Note that testing, using visual inspection must be performed with the rectifier ___ and ___ power disconnected and locked out. A) on, AC B) off, DC C) off, AC D) on, DC c The efficiency of a rectifier is calculated with a(n) ___meter A) amp-hour B) watt-hour b Percent Efficiency = A) DC Power Out/ AC power in x100 B) AC power in/ dc power out x 100 a calculate the efficiency of a rectifier with a DC output of 10 V 25A DC if the watt meter reads 500 W. A) 40% B) 60% C) 50% D) 70% A) 3, 9 B) 0.5, 1.0 C) 0.3, 0.9 D) 3, 6 E) "OL" (overload or out of limits) c In regards to a diode in a rectifier: In the reverse bias condition, positive lead to cathode and negative lead to anode, a functional diode will display ____ A) 3V, 9V B) 0.5V, 1.0V C) 0.3V, 0.9V D) 3V, 6V E) "OL" (overload or out of limits) e True or False (t or f) Diodes can be properly checked while in the circuit or with the power on f CANNOT How can diodes be tested in a rectifier A) turned off, locked out, disconnect secondary taps and DC cables B) turned off, locked out, disconnect primary taps, and DC cables END OF CHAPTER 4 a START OF CHAPTER 6 A structure-to-electrolyte potential is a measurement taken with the voltmeter connected in ____ in the circuit A) parallel B) series a Structure-to-electrolyte potential profile surveys are used to: I locate cathodic areas II locate anodic areas III locate stray currents IV locate coating holidays A) only II B) I, I, III C) III, IV D) II, III, IV d When attempting to minimize voltage drops while conducting a pipe to soil measurement _____ A) put the reference electrode in remote earth B) minimize the distance between the reference electrode and the surface of the structure C) measure the potential when the current flow is not interrupted (instant on) D) ensure external CP coupons in the vicinity of the structure to replicate a coating holiday b One of the disadvantages of structure to electrolyte potentials is that: A) all sources of CP current must be not be interrupted simultaneously, B) stray currents will affect the readings C) locate coating holidays D) is not straightforward b True or false (t or f) The averaging of the actual structure-to-electrolyte potentials means that surface measurements will detect small corrosion cells that are being cathodically protected f might NOT detect small corrosion cells that are NOT being cathodically protected In regards to structure to electrolyte: Because the meter circuit is a ____ circuit, the magnitude of the ____ that appears across the meter will be _____ to the ratio of the meter resistance to the total meter circuit resistance A) parallel, current drop, disproportional B) parallel, voltage drop, proportional C) series, voltage drop, proportional D) series, current drop, proportional c In regards to structure to electrolyte: For the measurement circuit, Kirchhoff's ___ law applies and the true potential difference is equal to the sum of the ____ drops around the ___ circuit. A) voltage, current, parallel B) voltage, voltage, series C) current, voltage, series D) current, current, parallel b Consider a true potential (E true ) of 1,000 mV, each test lead resistance (R tl ) of 0.01 Ω, a pipe-to-earth resistance (R p,e ) of 10 Ω, a reference electrode resistance to earth (R r,e ) of 100 kΩ, and a meter resistance (R m ) of 1 MΩ. Calculate the voltage that would appear across the voltmeter. A) 1000mV B) 800mV C) 909mV D) 850mV c 1) R t = 3R tl + R p,e + R r,e + R m = 3(0.01) + 10 + 10 5 + 10 6 R t = 1.1 MΩ 2) V m = R m / Rt * E Vm = 1.0Mohms / 1.1Mohsm * 1,000mV = 909mV For well coated pipeline, the equipotential field forms in ________ holidays A) close proximity to the B) remote proximity to the C) distant proximity to the a In regards to a well coated pipe: Typically __% of the total voltage drop between the reference and the steel exposed at the holiday is found within about ___ diameters of the holiday A) 50%, 10 B) 80%, 100 C) 95%, 100 D) 95%, 10 d In regards to a well coated pipe: For a 1 cm diameter holiday, ___% of the voltage occurs within a radius of __ cm from the holiday. A) 50, 10 B) 85, 100 C) 90, 10 D) 95, 100 c In regards to IR drop error determination and correction: One method to correct for IR drop is to place the reference electrode at ____ to include ____ and then ____ this error from potentials measured with the reference located ____ the structure A) close distance, max IR-drop, add, furthest from B) remote earth, max IR-drop, subtract, nearer C) remote earth, max IR-drop, add, furthest from D) close distance, min IR-drop, subtract, nearer b In regards to IR drop error determination and correction: One method to correct for IR drop is ____ the current in steps while measuring the change in structure- to-electrolyte potential and the resultant surface voltage gradient. A) increase B) decrease b Figure 6.8 The "instant-off" potential should be measured ___ spiking has ________ significant ____ of the structure has occurred. A) before, decayed but before, polarization B) before, decayed but after, depolarization C) after, decayed but after, polarization D) after, decayed but before, depolarization d Potential Measured (E m ) = A) IR Drop+ Depolarization+ True Potential B) IR Drop- Polarization+ E corr C) E corr Polarization IR Drop D) E corr + Polarization + IR Drop d Key factors in selecting an interruption cycle include I maintaining depolarization over the duration of the survey project II maximizing depolarization during the OFF period III minimizing depolarization during the day IV Ability to measure accurate OFF potential data after the "spike" has dissipated V maintaining polarization over the duration of the survey project A) I, II, III B) III, IV, V C) II, III, IV D) II, III, IV, V b True or False (t or f) In regards to current interrupters , the duty cycle is the percentage of ON time to OFF time Maintaining an ___% / ___% or ___% / ____% "duty cycle" is important to minimize ____ during the day and over the duration of the survey project A) 50/50 , 75/25 , depolarization B) 80/20 , 50/50, polarization C) 80/20 , 75/25, depolarization, polarization D) 80/20 , 75/25, depolarization, depolarization d True or false (t or f) Current interrupters should be left on during the night f it is important to turn off the current interrupters at night. This will reduce the amount of time the current sources are being cycled and help rebuild any polarization which may have been lost during the day when the current sources were cycling ON and OFF. Some ____ interrupters will fail in the on position when synchronized if they lose ___ signal and then restart when it comes back, unless there is a _____ monitoring the data A) quartz crystal, head spacing, data logger B) quartz crystal, satellite, meter station C) GPS, satellite, data logger D) GPS, head spacing, meter station c One method of verifying interruption synchronization and of checking the magnitude and duration of the inductive/capacitive spike is by recording a ____ or "wave print" A) wave scope B) current wave C) data logger D) waveform d Evidence that cathodic protection is working can be obtained by using ____ , they consist of ____ A) coupons, the same metal as the anode B) coupons, the same metal as the cathode b B) stepwise current reduction technique, current is increased C) stepwise current reduction technique, current is left constant a In regards to the stepwise current reduction technique: If the potential changes are recorded quickly, this technique can be used in the presence of ____ stray currents A) steady state B) telluric C) dynamic c True or False ( t or f) A close interval potential survey can be completed on both cathodically protected and non-cathodically protected structures t True or False (t or f) If the target CP criteria is the -0.850 V CSE polarized potential criteria, then typically an interrupted CIS is done where the ON and instant off are completed t For the 100 mV polarization criteria during CIS, the pipe must be ____ for a period of time, and CIS must be conducted at the same location during the initial CIS A) depolarized B) polarized a If a section of pipe has OFF potentials less negative than -0.850Vcse this indicates A) non adequate levels of CP B) adequate levels of CP a The graph illustrates what in the first and second half of the picture A) all critiea for CP have been met B) nearly zero IR drop in the ON potential in the second half C) ON and depolarized potentials are the same in the first half of the graph B Lateral/Side Drain Surface Surveys are completed during CIS projects on ______ protected pipes and are typically ____ and ____ ____ to the pipe A) non-cathodically, 10ft, 25ft, parallel B) cathodically, 15ft, 25ft, parallel C) non-cathodically, 10ft, 25ft perpendicular D) cathodically, 10ft, 20ft, perpendicular c In regards to Lateral/Side Drain Surface Surveys: anodic locations will only be those areas where the lateral potentials are less ____ than the over-the-pipe potentials A) negative B) positive a Is it better to have a permanent shunt or use an ammeter to measure current in a circuit? A) ammeter B) permanent shunt b True or False (t or f) When selecting a shunt, its current rating must exceed the anticipated circuit current and the millivolt drop at the anticipated operating current should be easily measurable on a standard digital multimeter t To measure very small current accurately, a ____ must be used A) ammeter B) multimeter C) zero resistance ammeter D) ohmmeter c Which test overcomes odd-sized joints within a pipe span to calculate current on the pipe A) 4 wire B) 2 wire C) Casing D) 6 wire a A _____ test point span can be used where a known length of pipeline and the diameter and wall thickness or the weight per foot are known. A) 4 wire B) 2 wire C) Casing D) 6 wire b If the voltage drop across a 200-ft (61-m) span of 30-in. (762 mm) pipe weighing 118.7 lbs/ft (176.65 kg/m) is 0.17 mV, pipe resistance/ft from Table 6.1 = 2.44 μΩ /ft (8.01 μΩ/m), then the current flow is A) 0.584A B) 0.234A C) 0.348A D) 1.234A c Pipe resistance/ft from Table 6.1 = 2.44 μΩ /ft (8.01 μΩ/m) = 0.00000244 Ω/ft = 200 ft x 0.00000244 Ω/ft = 0.000488 Ω I= E/R .17mV = 0.00017V 0.00017V / 0.000488ohms = 0.348A C) negative, positive D) positive, negate b A ______ is a method used to detect holidays in a pipe coating after the pipe is buried A) DCVG survey B) Pearson survey C) coating resistance survey D) pipeline current mapper b ____ is a method for detecting cathodic protection current pickup at coating holidays A) DCVG survey B) Pearson survey C) coating resistance survey D) pipeline current mapper a In regards to the Pearson survey: As the location of the coating holiday is reached, the radio signal becomes ____ on the receiver A) stronger B) weaker a It was developed to non-intrusively and accurately measure a near DC current temporarily impressed on the structure and therefore distributed along the pipeline A) DCVG survey B) Pearson survey C) coating resistance survey D) pipeline current mapper d In regards to the Pearson survey: As the two individuals continue walking, the signal will then ____ and when the back or second person approaches the holiday, the signal will again ___ and the point of the ___ is the location of the coating holiday. A) peak, peak, null B) null, null, peak C) null, null, null D) null, peak, null d In regards to DCVG: Where there is ___ coating defect, the analog voltmeter needle does ___ register movement. A) no, not B) definately a, not C) definately, definately D) no, definately a In regards to DCVG: This technique is accomplished by installing a ____in an existing ____ unit or by using a temporary CP system A) ammeter, rectifier B) current interrupter, rectifier C) voltmeter, rectifier D) resistance meter, rectifier b True or False ( t or f) In regards to DCVG: the interrupter is set to cycle at a very fast rate with the ON period less than the OFF period, such as a 1/3 second ON and 2/3 second OFF t True or False (t or f) In regards to DCVG: While walking along the pipeline route the probes are used as walking sticks making sure one electrode tip is in contact with the ground at all times t In regards to DCVG: ____ is/are always kept near the pipeline centerline ____ A one probe, while the other is held laterally at 1 to 2 m. B) two probes a True or False (t or f) In regards to DCVG: Where there is coating defect, the analog voltmeter needle does not register movement f where there is NO coating defect the analog voltmeter needle does not register movement. In regards to DCVG: The amplitude of the needle swing will ____ as the defect is approached and ____ when passed. A) increase, increase B) decrease, decrease C) decrease, increase D) increase, decrease d In regards to DCVG: Signal strength at TS A = 200mV Signal strength at TS B =300mV Defect from TS A = 1,372m Defect from TS B = 457m What is the estimated signal strength at defect A) 295mV B) 350mV C) 275mV D) 175mV c 3) What is the pipe-to-earth resistance or the pipe coating resistance? 4) What is the specific coating resistance? 1) 0.975Volts 2) 0.10A 3) 9.75 ohms 4) 323,291 Ω-ft 2 ____ is the ____ of resistance A) Conductance, reciprocal B) Inductance, reciprocal a What is the unit of measure for conductance? A) resistance B) conductors C) capactiance D) siemens d Current Requirement Tests, given: 1) Static pipe-to-soil potential = -0.645 V CSE 2) Desired polarized p/s potential = -0.850 V CSE 3) Test current = 50 mA (0.05 4) Polarized potential due to test current = 0.775 V CSE A) 100mA B) 200mA C) 78.8mA D) 87.8mA c I req = (Δ E preq * I test) /( Δ E ptest) The value of resistance producing IR drop R = (E ON - E OFF )/I ON I req = [0.850 V - 0.645 V] 0.050 A / (0.775 − 0.645) = 78.8mA This type of pipe locator uses AC current A) inductive B) conductive b This type of pipe locator uses frequency AC signal A) inductive B) conductive a True or False (t or f) When doing the structure to electrolyte potential for isolation testing the reference electrode must be placed in two different locations f same location When conducting the DC Line Current to Test Isolation how far apart must the two electrical connection points be A) at least 10 feet apart B) at least 50 feet apart C) at least 100 feet apart D) at least several hundred feet d In this test, a reference electrode is connected to one lead from a multimeter and placed at a fixed location while the second lead from the multimeter is placed in contact with various parts of the structure A) DC Line Current to Test Isolation B) Fixed Cell to Moving Ground for Continuity Test C) Interrupted Structure-to-Electrolyte Potential to Test Isolation D) Current Response c Applying a temporary current to one side of an electrical isolation device can determine if the device is functioning properly, with this test ______ A) DC Line Current to Test Isolation B) Fixed Cell to Moving Ground for Continuity Test C) Interrupted Structure-to-Electrolyte Potential to Test Isolation D) Current Response d With casing shorts the metallic short might attenuate or ____ A) become more positive B) become more negative C) stay the same a When conducting a structure to electrolyte potential survey on a casing, if the two potentials are less than ___mV, the casing might be shorted to the carrier pipe A) 5 B) 50 C) 100 D) 150 c B) 18,320 ohms-cm C) 15,320 ohms-cm D) 11,320 ohms-cm c ρ = 191.5 x 10 ft x 8 Ω = 15,320 Ω -cm When taking soil resistivity measurements along a structure,it is good practice to place the line of pins _____ to the structure, with the nearest pin no closer than ___ ft from the structure A) parallel, 20 ft B) parallel, 10ft C) perpendicular, 20ft D) perpendicular, 15ft d Layer Resistivity 1) S 2 layer = 318.2 cm - 159.1 cm =159.1 cm 2) R 2 layer = (R 1 R 2 ) / (R1 - R2 ) = 28.46ohms 3) 2 π x 159.1cm x 28.46 Ω = 28,450ohms-cm The soil box measures a ____ or resistivity of a relatively small soil sample A) maximum B) minimum b True or False (t or f) One advantage of the single rod method for measuring resistivity of soil is that it can be employed in confined spaces such as next to tanks and between pipes t What is the formula for resistivity A) p= (L*A)/(R) B) p = (R*A)/(L) C) p = (X*A)/(R) b Electrical continuity of concrete rebar structures can be evaluated using ______ a resistance of less than ____ indicates continuity A) DC-resistance measurements, 0.100 ohms B) AC-resistance measurements, 0.100ohms b In regards to concrete rebar structures and CP The ___ must not come into contact with the rebar or any other metallic component of the structure A) anode B) rectifier C) cathode a In regards to concrete rebar structures and CP Potentials more positive than ___ mV have a ___ chance of corrosion A) -300, 10% B) -200, 10% C) -150, 5% D) -200, 5% d In regards to concrete rebar structures and CP Potentials more negative than ___ mV have a ___ chance of corrosion A) -350, 90% B) -350, 95% C) -200, 80% D) -200, 95% b In regards to leaks vs time It is typical of corrosion that the cumulative frequency increases _____ with time A) straight line fashion B) fast in the beginning , slower C) logarithmically END OF CHAPTER 6 c START OF CHAPTER 7 ___ stray current is can cause significant corrosion of aluminum, ___ stray current causes signficant corrosion of most metals A) DC , DC B) AC, DC C) DC, AC b ______ allows us to relate the corrosion lost to the amount of current discharged A) Faraday's Law B) Ohm's Law C) Kirchoff's Law a These currents can be manmade or natural in origin A) Telluric B) Steady State C) Dynamic c The damaging effect of stray current typically occurs if the current ____ the structure through the electrolyte where corrosion will be accelerated A) remains on B) leaves b This is an example of stray current using varying voltage gradients with two reference electrodes A) outside the area of influence B) inside the area of influence a If a foreign structure crosses a voltage gradient that is with respect to remote earth, then it will promote current pickup on the ____ , ____the area of influence, this is anodic interference A) negative, protected structure, outside B) positive, foreign structure, outside C) positive, foreign structure, within D) negative, protected structure, within c During anodic interference current will discharge ____ the area of influence A)outside B) inside a In a(n) ______ pipeline, the corroding (anodic) areas exhibit a potential that is more _____ when measured against a reference electrode, while the non-corroding (cathodic) areas yield a more ____ potential. A) protected, negative, positive B) protected, positive, positive C) unprotected, positive, negative D) unprotected, negative, positive d In a(n) ______ pipeline, the corroding (anodic) areas exhibit a potential that is more _____ when measured against a reference electrode, while the non-corroding (cathodic) areas yield a more ____ potential. A) protected, negative, positive B) protected, positive, negative C) unprotected, positive, negative D) unprotected, negative, positive b In regards to testing for stray current interference with an interrupter installed: Assumption that the ___ potential is the most ____ value must NOT be made A) ON, negative B) ON, positive C) OFF, negative D) OFF, positive a Which of the following is likely indicating cathodic interference A) X B) Y C) Z b Which of the following is likely indicating anodic interference A) X B) Y C) Z a True or False (t or f) Current measurements within a structure such as a pipeline can be used to predict current pickup and discharge areas t In regards to the installation of metallic bonds to control interference: The resistance of the bond must be ___ than the ___ path through the soil A) lower, perpendicular B) higher, perpendicular C) lower, parallel D) higher, parallel c