PMMI Industrial Electricity Practice Test

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• The apparent power S is calculated as S = V_rms × I_rms. If V_rms = 460 V and I_rms = 8 A, what is S?
• What is the total power of 4 quarter watt resistors wired in Parallel?
• Which NEC article covers motors and motor circuits?
• In an AC circuit, the resistance offered by a capacitor is called what?
• Which two fault types are targeted by protection coordination?
• What is an on-delay timer in a ladder logic circuit?
• Which statement about EMI is accurate?
• Based on the chart and schematic, between which two points is there an open circuit (with measurements referenced to E)?
• In an AC motor, which component remains stationary during operation?
• What is the primary purpose of a Variable Frequency Drive (VFD) in motor control?
• Protection coordination isolates which faults?
• What does a motor's service factor tell you about its ability to handle overloads?
• True or False: Power is conserved across an ideal transformer, so if the voltage decreases, the current increases proportionally.
• What is the voltage output of a transformer supplied with 480 V, 50 Hz, and a turns ratio of 4:1?
• In a typical three-wire AC power cord, which color is the Neutral wire?
• In a ladder logic rung, what does the rung typically represent?
• Which statement about the coil of a relay is false?
• What is the correct method to verify proper equipment grounding in a facility?
• Which instrument is used to measure resistance?
• The total resistance in a circuit is measured as 12 ohms in a parallel network. Which fault is most likely?
• Which form of Ohm's Law expresses current as the voltage divided by resistance?
• In a 480 VAC three-phase wye system with a neutral, what are the phase-to-phase and phase-to-neutral voltages?
• Which derating practice is used when ambient temperatures are high in electrical installations?
• What is the role of a thermal overload in motor protection coordination with a contactor?
• Which component stores energy in a magnetic field?
• Which statement about service factor is true?
• Capacitance is measured in units called:
• Which statement is true for a parallel circuit?
• In an AC circuit, cos(phi) equals R divided by Z. If R = 12 Ω and Z = 20 Ω, what is cos(phi)?
• What is lockout-tagout (LOTO) and why is it essential for electrical maintenance?
• In a three-phase wye connection, line-to-line voltage is related to line-to-neutral by V_line = sqrt(3) × V_phase. If V_line = 480 V, what is V_phase to the nearest volt?
• In a typical three-wire AC power cord, which color wire is considered the Hot wire?
• What is the purpose of a thermal overload relay in a motor circuit?
• What is the total power used in a circuit that has ten single phase motors wired in parallel? Each motor pulls 2A at 240VAC with a frequency of 60Hz.
• In a series circuit, which statement is true?
• To reverse a three-phase motor safely, which method should you use?
• To measure the voltage drop in a circuit, the voltmeter should be connected in the circuit by:
• Which equation correctly relates input power, output power, and efficiency for a motor?
• Which statement correctly identifies what is used to determine PPE category for arc flash?
• What is the purpose of insulation resistance testing (megger), and what indicates good health?
• Which of the following is not typically involved in determining voltage drop in a feeder?
• When selecting overcurrent protection for a motor, what is a key difference between fuses and circuit breakers?
• Which statement best describes real power, reactive power, and apparent power in AC circuits?
• In a DC circuit, what is the relationship between voltage, current, and resistance?
• Which formula correctly calculates the full-load current for a three-phase motor given horsepower, line voltage, efficiency, and power factor?
• What is an isolation transformer, and why would you use one in a control panel?
• What is the proper method to measure current in a portion of a circuit?
• Which instrument is used to measure current in a circuit?
• A 1200W load on a 120V supply draws how many amperes?
• Which setup is commonly used to check continuity in a circuit?
• How many 1200-watt hair dryers can be operated by a 120V circuit protected by a 20 amp circuit breaker?
• The difference in electrical potential between two points is defined as
• Which device stores energy in an electric field and has capacitance measured in Farads?
• The energy stored in a capacitor is called:
• What is the purpose of the NC contact labeled 'R' in line 1?
• Compared to IE2, IE3 motors are...
• Which device is typically used to control one circuit with contacts in another circuit?
• For a circuit with V_rms = 480 V, I_rms = 10 A, and power factor cos(phi) = 0.8, what is the real power P?
• A transformer has turns ratio N1:N2 = 2:1. If the primary voltage is 480 V, what is the secondary voltage (assuming an ideal transformer)?
• Which statement about ladder diagrams is true?
• What term describes a break in a circuit that prevents current flow?
• The difference in electrical potential between two points is defined as
• Which statement best describes a systematic approach to troubleshooting electrical problems?
• How many overloads are needed for a 3-phase induction motor?
• A motor starter contains a coil, contacts, and overloads.
• A 240 VAC source is connected to a 1200 Watt 3-phase motor. How much current is flowing to the motor?
• In ladder diagrams, what do normally open (NO) and normally closed (NC) contacts represent?
• A single motor drawing 2 A at 240 V consumes how much power?
• If a motor has a full-load current of 15 A, the typical starting current under direct-on-line starting would be approximately which range?
• Which nameplate data are most important when sizing protective devices for a motor?
• What is the function of a ground-fault circuit interrupter (GFCI) and where is it typically required?
• What is the preferred method to verify proper equipment grounding in a facility?
• What is the total power of 4 quarter watt resistors wired in series?
• NFPA 70E governs what critical aspect of industrial electrical work?
• Which statement correctly describes a NOR gate?
• What is the equivalent resistance of three 30 Ω resistors in parallel?
• What is the purpose of THHN insulation and what is a common temperature rating used in industrial wiring?
• The voltage across all components in a series circuit adds up to the source voltage.
• In a 240V, 20A two-wire branch circuit, the maximum allowable voltage drop is 2.4V. Using Ohm's law, what is the maximum conductor resistance?
• How can motor overload be detected in operation?
• How does ambient temperature affect conductor ampacity, and what NEC practice addresses this?
• Which law is used to relate voltage drop, current, and resistance in conductor calculations?
• What is a contactor and its typical use in motor control?
• What effect can harmonics have on the neutral conductor in systems with non-linear loads?
• What is the voltage output of a transformer with turns ratio 3:1 and a 240V DC primary?
• Inductance is measured in which unit?
• Conductor ampacity is determined by
• An open in a circuit is:
• True or False: In an ideal transformer, power is conserved (P = VI) so voltage changes on one side require proportional current changes on the other.
• How does phase sequence affect the rotation direction of a motor, and how can you correct incorrect sequence?
• According to Ohm's law, what voltage is required to push 1 amp of current through 1 ohm of resistance?
• A 240V load drawing 7A placed on a transformer rated 1,500 VA with 240V output would cause the transformer to be ...
• What is another name for voltage?
• What is the relationship between real power, apparent power, and power factor in a three-phase system?
• What is the total resistance of the circuit shown?
• What is the state of a normally open (NO) contact when the coil is de-energized?
• Motor slip is defined as
• What is the role of protection relays in power circuits?
• What is the proper procedure to measure current in a specific portion of a circuit?
• A three-way switch uses which type of contacts?
• Which statement about a contactor’s coil is accurate?
• Transformers are used to change a source's:
• A transformer step-down with turns ratio 6:1 reduces the voltage by a factor of 6; if the primary is 480 V, the secondary would be
• Two 1200W hair dryers on a 120V circuit with a 20A breaker would ...
• Using Q = V_rms × I_rms × sin(phi), if V = 230 V, I = 5 A, and sin(phi) = 0.6, what is the reactive power Q?
• How should a fuse be installed in a circuit to insure proper operation?
• How does a relay differ from a contactor in duty and current rating?
• Which instrument is used to measure current in a circuit?
• What is the DC ohmic relationship fundamental to circuit analysis?
• If a transformer has a VA rating of 1,500, a source voltage of 480VAC and the output voltage is 240VAC, what is the approximate maximum current that can be safely delivered by the transformer?
• What is the function of a soft starter, and how does it differ from a variable-frequency drive?
• How do common-mode EMI and differential-mode EMI differ?
• Power in a circuit can be determined by
• What is the purpose of shielding in control cables?
• Wire numbering serves which purposes?
• What term is used to describe the reactive power component that represents energy stored in magnetic and electric fields and oscillates between the source and the load?
• Which statement best describes the shown logic: If (CR1 and CR2 and CR3) or (CR4 and not CR5) then CR6?
• Motors draw full-load amperes (FLA) when they are:
• How does grounding electrode resistance affect fault currents in a building?
• Which of the following lists correctly identifies the four basic components of a simple electrical circuit?
• What is the current through resistor R4 in the circuit?
• A meter is placed on wire 1 and wire 3. PB1 is closed. A reading of source voltage is given. What does this indicate?
• Which of the following stores energy in an electric field?
• Which component isolates the load from the supply to reduce noise in a control panel?
• When is a push-to-test pilot light generally used in circuits?
• The purpose of the neutral wire in a 4-wire system is
• Direct-on-line starting vs star-delta starting for a 3-phase induction motor: DOL applies full line voltage with high inrush, while star-delta starting reduces starting current to about one-third by starting in star and then switching to delta. Which starting method yields starting current about one-third of the full-load current?
• What is the total power in a circuit where the calculations yield 20 watts?
• In a parallel circuit, if one branch short circuits, the remaining branches generally continue to operate.
• In a DC circuit, after a capacitor has charged, the capacitor behaves as which for the rest of the circuit?
• Ohm's law application: If a circuit has 12 V and 3 Ω, what is the current?
• If multiple identical loads are connected in parallel to the same voltage, the total power is the sum of the individual powers.
• The unit of electrical resistance is:
• Which of the following factors is not directly used to determine conductor ampacity?
• In a transformer with turns ratio 10:1 (step-down), which statement correctly describes current flow?
• What is the primary function of a motor control center (MCC)?
• What is the voltage output of a transformer whose turns ratio is 6:1 and has a primary voltage of 240VAC?
• Which device is used to automatically disconnect a circuit when a fault is detected?
• In an AC circuit with resistance R = 8 Ω, inductive reactance X_L = 20 Ω, and capacitive reactance X_C = 5 Ω, what is the impedance Z?
• How is motor efficiency typically indicated on nameplates (example), and what does it signify?
• The voltage law that states that the total voltage of a series circuit is equal to the sum of all the voltage drops is
• How is arc-flash incident energy typically determined, and what does it drive in PPE selection?
• The coil of a relay is energized by applying voltage across its terminals; it is considered what kind of device?
• What is the typical starting current of an induction motor under direct-on-line starting relative to its full-load current?
• What kind of logic is shown?
• FLA in motor terminology stands for which of the following?
• What is the difference between an on-delay timer and an off-delay timer?
• In a 208VAC, three-phase power source, what is the nominal voltage level from any phase to ground?
• If a resistor has 2 ohms resistance and 6 volts across it, the current is?
• How can you determine whether a motor is overloaded in operation?
• Which statement is true about a 4:1 transformer, in terms of voltage source side and output?
• Which component stores energy in an electric field?
• Voltage across a set of closed N.O. contacts should be
• In mutual induction, what passes between conductors to create voltage?
• Three identical resistors R in parallel have an equivalent resistance of R/3.
• As frequency increases, which statement about reactance is true?
• What does the service factor on a motor nameplate indicate?
• In a circuit with resistors R1 through R5, which resistor, when disconnected, leaves the ohmmeter reading the same as when all resistors are connected?
• If 3, 30ohm resistors are connected in parallel and supplied with 20VDC, what is the total current flow in the circuit?
• A transformer with a 1:1 turns ratio and a 240 V primary delivers what secondary voltage?
• Which statement best describes the intended benefit of a Variable Frequency Drive beyond speed control?
• For a transformer with a turns ratio of 10:1, the secondary current is approximately how many times the primary current in an ideal transformer?
• How is voltage drop calculated for a feeder feeding a motor load, and what factors affect it?
• Which instrument is used to measure resistance in a circuit?
• In order to reverse the direction of a 3-phase motor, you should
• The actual speed of a squirrel cage induction motor is:
• What type of logic is shown in the below diagram?
• Define equipment grounding and bonding and state their primary purposes in an industrial installation.
• What is the purpose of an electrical ladder diagram?
• In a series circuit, the total resistance equals the sum of the resistances.
• All equipment capable of conducting current must be grounded, indicated by which color(s)?
• The coil of a relay is a(n):
• Which statement best describes the behavior of a capacitor in DC circuits according to the material?
• Which color indicates a ground wire in some color schemes?
• An AC electric motor has two main parts. Which pair correctly identifies them?
• A circuit with three 30 Ω resistors in parallel is connected to a 20 V source. The total current drawn is:
• A battery and a test light can be used to:
• Which of the following describes inductive reactance?
• Which method below is the most important way to prevent electrical shock hazards?
• As frequency of an AC source decreases, which of the following statements is true?
• When a short occurs in one branch of a parallel circuit, the other branches will continue to operate.
• Three-phase device with windings X1-X2, Y1-Y2, Z1-Z2. In a Delta configuration, which connection scheme wires the device to incoming conductors A, B, and C?
• What is the primary purpose of an isolation transformer in a control panel?
• In a three-phase system, the line-to-neutral voltage on a 208V system is which value?
• The unit of electrical resistance is measured in
• What is true of a capacitor in a DC circuit?
• Which statement best describes shielding in control cables?
• What is the function of an inductor in a circuit?
• If the primary current is 3 A in a transformer with a 4:1 turns ratio, what is the approximate secondary current?
• Distinguish between equipment grounding and bonding with a practical example.
• In a three-phase system, with V_line 480 V, I_line 21 A, and PF 0.85, the apparent power S is approximately what?
• To calculate voltage drop in a conductor, which quantities are needed?
• In switchgear, what is the primary function of a busbar?