Download 2025 Electrical engineering-NEIEP 400 course test review with 124 detailed solutions. and more Exams Electrical Engineering in PDF only on Docsity!
course test review with 124 detailed
solutions.
2025 Electrical engineering-NEIEP 400
course test review with 124 detailed
solutions.
What is true when placing an ammeter into a circuit? - ANSWER-The meter is placed in series with any component.
What describes the most useful feature of the clamp-on ammeter? - ANSWER-Does not require that connections be disturbed.
To what scale should the ammeter be set to read a current of 2000 ma? - ANSWER-10 amp
what device is an example of a reactive component that can store energy for long periods of time causing an electrical hazard even with power removed? - ANSWER-Capacitor
What must be done when testing resistance to avoid false readings caused by parallel circuit paths? - ANSWER-Remove one of the two wires to the item being tested.
A minus sign in front of a reading of the digital voltmeter indicates what? - ANSWER-The positive lead is connected to the negative source.
What measurement does the meter in figure 1 indicate? (Meter in picture reads 0.790 M ohms) - ANSWER-790 k ohms
The AC voltage as read on a digital voltmeter is always indicated as? - ANSWER-RMS
What is the probe to probe resistance of the meter leads of a digital meter when they are plugged into the common and 10A jacks? - ANSWER-Short circuit
course test review with 124 detailed
solutions.
what is indicated by the 0 reading on the meter in figure 2? (leads are connected to 120 VAC battery one lead connected to 10A, the other to COM. Meter is set to A~ function) - ANSWER-The internal fuse is blown and possible meter damage.
what is indicated by a resistance measurement of .250 M ohms on a digital multimeter? - ANSWER- 250,000 ohms
What should the resistance of a motor generator commutator be to ground with brushes raised? - ANSWER-infinite resistance
What procedure could be used to test the current drawn by a DC hoist machine brake coil? - ANSWER- Measure the voltage across a precision shunt placed in series with it.
What is indicated by the reading on the meter in figure 3? (meter reads 2230 ohms, on ohms setting. leads connected to ohms and COM jacks. - ANSWER-2.23 k ohms
What is the result of connecting an ammeter to the terminals of a power supply or other voltage source? - ANSWER-The meter will be damaged.
What is correct regarding the transformer? - ANSWER-applied voltage on the primary leads current by 90 degrees
What does two solid lines between two coils represent in a transformer? - ANSWER-Iron core transformer
What statement best describes CEMF? - ANSWER-it opposes the applied voltage
In figure 2 what will be the phase relationship between the primary and secondary voltages? (figure two is a picture of an iron core transformer with one dot to the top left of the iron core symbol and another
course test review with 124 detailed
solutions.
Which of the following would describe a transformer with a primary current of 27 amps and a secondary current of one amp? - ANSWER-step down transformer
how are primary windings on a transformer identified? - ANSWER-the primary winding terminals are identified with the letter H
how would you check for an open primary winding? - ANSWER-measure the resistance across the primary.
What is true of resistance when a secondary winding is open? - ANSWER-the secondary resistance will be infinity.
which statement applies when a secondary winding is completely shorted? - ANSWER-current through the primary is high.
which statement applies when a secondary winding is partially shorted? - ANSWER-current through the secondary is low.
the direction of the magnetic field around a wire when electron current flows through it can be determined by ________________? - ANSWER-The left hand rule.
What are naturally magnetic materials called? - ANSWER-Ferromagnetic
What is the direction of electron current flow? - ANSWER-negative to positive.
What is the output of an elementary generator called? - ANSWER-Alternating Current
course test review with 124 detailed
solutions.
What is the action in the elementary DC generator of converting AC to DC called? - ANSWER- Commutation
More coils and commutator segments are added to the elementary DC generator Armature in order to help it do what? - ANSWER-Reduce Ripple
What happens if more turns are added to each armature coil in a DC generator? - ANSWER-Increased voltage output
If a current carrying wire is placed perpendicular to a field created by two magnets of opposite polarity what happens? - ANSWER-The conductor is moved at right angles to the flux of the magnetic poles.
What does the right hand rule for motors determine? - ANSWER-Direction of the current carrying conductor movement in a magnetic field.
What is the inherent current-limiter present for a rotating motor armature called? - ANSWER-CEMF
What effect does the EMF produced through induction have on the applied EMF of a motor armature? - ANSWER-opposes the applied EMF
what is true about magnetic lines of force? - ANSWER-They never cross one another.
What does the amount of induced voltage in a wire depend on when moving it through a magnetic field? - ANSWER-Strength of the magnetic field and speed of the wire.
What is electromagnetism? - ANSWER-Magnetism created by current flowing through a coil of wire.
what elements are present when operating a motor or generator? - ANSWER-A magnetic field, current and Rotation or motion.
course test review with 124 detailed
solutions.
The shaft of a DC machine is made of how many pieces? - ANSWER-
How is an armature shaft balanced at the factory or repair facility? - ANSWER-adding or removing epoxy weights to the shaft or windings.
Mica is used as an? - ANSWER-Insulator
What do commutators do? - ANSWER-Pass current between the brushes and armature windings, provide switching and turn with the armature.
What is used to lubricate a sleeve bearing? - ANSWER-oil
What is used to lubricate a ball bearing? - ANSWER-high temperature grease.
the frame of a DC machine is? - ANSWER-sometimes called a yoke, The main support for the machine components and Made of electrical grade steel.
Which of the following identifies waste currents induced in the core material of the armature and field pieces? - ANSWER-Eddy Currents
What does the brush rigging fasten to? - ANSWER-one of the end bells.
In a separately excited generator, where does field excitation current come from? - ANSWER-An external power source.
What are the two circuits of a separately excited generator called? - ANSWER-The shunt and series circuit.
course test review with 124 detailed
solutions.
How is a magnetic field produced in a field coil? - ANSWER-current must pass through it.
In a DC series generator when does current flow? - ANSWER-only when there is a load.
What is used to control exciter output voltage level? - ANSWER-The strength of the shunt field.
An elevator that travels faster in the up direction when it is fully loaded than it does when it is empty is ____________ compounded - ANSWER-over compounded
as load is increased in a shunt generator what happens to its output? - ANSWER-output drops as load increases.
what does the series field aid in a cumulatively-compounded generator? - ANSWER-the series field aids the shunt field.
What is the generator series field connected in parallel with? - ANSWER-The series shunt field.
How is motor speed changed? - ANSWER-By varying the field or armature voltage.
What type of generator uses two fields? - ANSWER-compound generators
What is a series field connected in series with? - ANSWER-The armature.
How is an exciter field circuit excited? - ANSWER-it is self-excited
course test review with 124 detailed
solutions.
a light electrical load on a commutator causes which of the following conditions? - ANSWER-threading
How can an eccentric commutator be corrected? - ANSWER-turning the commutator with a lathe tool.
To detect a high resistance ground, what instrument should be used? - ANSWER-Megger
The field protective relay has a contact in what circuit? - ANSWER-Safety circuit
an oil carrier ring is used to lubricate what type of bearing? - ANSWER-Sleeve bearing
A growler is used to detect short circuits in what? - ANSWER-Armature
Which material would you use to seat brushes? - ANSWER-Sandpaper
What angle are the brush holders on a DC reversible motor? - ANSWER-Radial
What could an electrical overload on the generator armature cause? - ANSWER-Heavy slot-bar marking
What is the most common cause of bearing failure? - ANSWER-abrasion from dirt and dust.
Which statement is true of sleeve bearings? - ANSWER-They require more care than ball bearings.
What is the most common cause of commutator problems? - ANSWER-Brush pressure too light
What is the result when brush grades are mixed on a commutator? - ANSWER-The results are unpredictable.
course test review with 124 detailed
solutions.
What should you do when cleaning a DC machine end bell? - ANSWER-Avoid contacting the armature and brushes with solvent.
where does high mica come from? - ANSWER-it comes from normal electrical or mechanical wear.
Describe a split phase motor - ANSWER-it uses the difference in winding inductance to offset the phases.
What is repairable on fractional horse power motors? - ANSWER-Brush replacement.
What is a motor that can be run on both AC and DC? - ANSWER-Universal motor
What device is used to prevent starting in wye and delta concurrently? - ANSWER-Walking beam
Regarding universal motors what can be said about the field and armature? - ANSWER-Current flows in the same direction.
AC induction motors use a _______ to act as a rotating field? - ANSWER-stator
What is the rotating speed of a three phase 60hz 4 pole motor? - ANSWER-1800 RPM
What is the rotating speed of a three phase 30hz 6 pole motor? - ANSWER-600 RPM
what is synchronous speed? - ANSWER-The rotational speed of the stator's magnetic field on an induction motor.
