NACE CP1 Book Chapters 1-4 exam Questions with 100% Correct Answers | Verified | Updated, Exams of Advanced Education

Download NACE CP1 Book Chapters 1-4 exam Questions with 100% Correct Answers | Verified | Updated and more Exams Advanced Education in PDF only on Docsity! NACE CP1 Book Chapters 1-4 exam Questions with 100% Correct Answers | Verified | Updated 2023-2024 Power rate at which energy is used by an electrical device (P=VI, necessary to know power required by CP rectifier to size AC supply circuit) Longer wires (series) = ____ resistance and ____ current for given voltage higher, lower Cable running to groundbed represents ____ circuit and groundbed itself represents ____ circuit series, parallel DC direct current (flows in one direction, produced by a battery) AC alternating current (reverses direction, hertz represents a cycle) How can AC be turned to DC? a rectifier What is a transformer? used to increase or decrease voltage or isolate incoming voltage source from outgoing voltage Primary winding of a transformer is connected to... the voltage source Secondary winding of a transformer is connected to... the unit to which voltage is to be supplied primary voltage / secondary voltage = # of primary turns / # of secondary turns In CP rectifiers, taps are located in the ____ winding so that several voltage adjustments are possible secondary Impedance total opposition that a circuit presents to AC (similar to resistance in a DC circuit, also depends on frequency and wave shape of current) D'Arsonval movement stationary permanent magnet/moving coil system of analog meter When using an analog meter, what terminal is the reference electrode connected to? positive Voltmeter measures voltage in response to current flow and series resistance through coil (more sensitive at lower voltages) Ammeter measures current flow with resistors (shunts) in parallel Ohmmeter measures resistance (limited in corrosion work) Why are ohmmeters limited in corrosion work? (2) ohmmeter cannot distinguish between resistance of isolation fitting and resistance through electrolyte, voltage difference between two isolated structures affects total voltage of circuit and creates errors In areas with stray current, which type of meter is better and why? analog, because a digital meter takes measurements several times per second and if voltage is fluctuating it is difficult to read a specific value As pH decreases, corrosion rate... increases Why does the corrosion rate of Al, Zn, and Pb (____ metals) increases with pH above 8? amphoteric, protective oxide film on surface is dissolved in most strong acids and alkalis Electrolytes with higher ionization have ____ conductivity greater External circuit metallic/electronic path Voltage measurements made in CP surveys (5) driving voltage of galvanic anode system, rectifier voltage output, structure to electrolyte potential, voltage drop across a pipe span, voltage across a current shunt 1. constant voltage = DC voltage remains constant for all current outputs up to rated max current 2. constant current = current output remains constant over range of resistances up to max rated voltage 3. constant potential = current and voltage output vary to maintain pre-selected structure potential All electrical connections in ICCP systems must be completely sealed with... dielectric insulating materials Low soil resistivity ____ CP by ____ anode-to-earth resistance, allowing ____ current output for a given voltage enhances, lowering, higher Coating ____ the amount of current required to protect a structure reduces Tight soils (clay, silt) may ____ depolarization, thus ____ protective current requirements reduce, reducing Oxygen can easily penetrate through porous soils (sand, gravel, glacial till), acting as a depolarizer, thus ____ current requirements increasing Increasing temperature ____ polarization and ____ current requirements reduces, increases As oxygen levels increase, polarization ____, ____ current requirements decreases, increasing As the relative velocity increases, the current requirement ____ due to ____ polarization increases, decreasing Bacteria (SRB) can have a depolarizing effect, ____ CP current requirements increasing A shorted pipeline is an example of metal (electric) ____ shielding What is the true criteria for eliminating corrosion? polarization of the cathodic sites to the open circuit potential of the anodic sites IR drop through the electrolyte can be reduced to nearly zero by placing the ____ near the structure, or by interrupting ____ in the electrolyte reference electrode, current flow NACE criteria for cathodic protection 100mV of cathodic polarization, -850mVCSE or more negative structure-to-electrolyte potential (direct measurement of polarized potential or a current-applied potential) How can IR drop be eliminated? (2) removing resistance of electrolyte, shutting off current Aluminum is an ____ metal, and a polarized potential more negative than ____ mVCSE should not be exceeded amphoteric, -1200 In salt water, a negative voltage of at least ___ mVSSC is the CP criteria -800 Non-homogeneity in soils can cause ____ areas to arise, because it leads to a ____ difference anodic, voltage How is the power source connected in an ICCP system? (circuit) in series What is the greatest primary anode reaction? 2H2O > O2 + 4H+ + 4e- oxygen evolution What does the copper-copper sulfate reference electrode consist of? copper rod immersed in saturated copper sulfate solution What is a close interval potential survey? series of structure-to-electrolyte potentials measured by carrying a data logger (or GPS-triggered device) with distance measuring capability over top of structure How to determine direction of current flow during CIS? from positive reference electrode to negative reference electrode What instrument can measure and store data taken at regular intervals over a period of time? data logger A voltmeter is connected in... parallel An ammeter is connected in... series The internal resistance of an ammeter should be ____ to prevent adding resistance to the circuit, thus ____ the current of the circuit low, reducing Because the ____ internal resistance of an ammeter impacts current flow, ____ are favored due to their known resistance value that helps with accuracy low, shunts What does a clamp-on ammeter measure? magnetic field created by the current through metallic path In using a shunt, you measure ____ across a known ____ and calculate ____ voltage drop, resistance, current Typical applications of current measurement in CP surveys (5) current output of galvanic anodes, rectifier current output, test current to determine structure current requirement, current flow on a structure (voltage measurement, current is calculated), current flow across a bond What is a 2-wire line current test? means of calculating line current flow across 2-wire test point span if the length, diameter, and wall thickness or weight per foot is known What is a 4-wire line current test? means of calculating line current even if dimensions of pipeline are unknown (pass known voltage, measure voltage change across span, calculate current using calibration factor K) What is the purpose of a resistance bond (or cable)? placed between structures to connect them for CP or to drain stray current back to its source Why is using an ohmmeter to measure effectiveness of an isolation joint not reliable? parallel resistance paths through soil What is the purpose of electrical isolation? confine CP current to the structure being protected What are some locations where electrical isolation can be compromised? (4) crossing structures, attachments (RMUs, valve operators, gauge lines, etc.), casings, grounds How to know if an isolation fitting is effective?