Transformers Lvl II Test Prep questions
and answers
A ? is a coil added in series with a load to reduce inrush current voltage notching effects and
voltage spikes.
a. capacitor
b. polarized-frequency relay
c. reactor
d. silicon-controlled rectifier ✔✔Reactor
Rectifiers are used in the starters of large synchronous motors to provide a voltage to the AC coil
of the polarized-frequency relay. t/f ✔✔True
Drive isolation transformers and like reactors both provide reactive control of distorted like
current harmonics and line notching t/f ✔✔True
Drive isolation transformers cannot provide protection from common mode transients that
originate with the primary source t/f ✔✔False
Drive isolation transformers protect the primary source from common energies that originate
with motor drive system and can prevent ground current from transferring back through primary
ground system t/f ✔✔True
Match corresponding letter of the saturable core transformer ✔✔pg 159
, A ? is a distortion in a voltage waveform where the voltage quickly drops toward zero and then
returns to the correct value. ✔✔notch
The opposition to current flow that is only present in AC is ? . ✔✔reactance
A ? is an inductor whose inductance is controlled through the use of a magnetic field created by a
second winding wound around the same iron core as the primary winding. ✔✔saturable-core
ractor
Electric motors typically draw many times their full-load current during startup. ✔✔True
a reactor should have about ? impedance to reduce notch depth by about 50% ✔✔3%
All two-winding transformers are isolation transformers ✔✔True
? is a type of electromagnetic interference induced on power or communication lines
✔✔Common-mode noise
a ? is a reactor used to reduce common-mode noise current generated by the rapid switching of a
motor drive or a signaling device ✔✔Common-mode choke
and answers
A ? is a coil added in series with a load to reduce inrush current voltage notching effects and
voltage spikes.
a. capacitor
b. polarized-frequency relay
c. reactor
d. silicon-controlled rectifier ✔✔Reactor
Rectifiers are used in the starters of large synchronous motors to provide a voltage to the AC coil
of the polarized-frequency relay. t/f ✔✔True
Drive isolation transformers and like reactors both provide reactive control of distorted like
current harmonics and line notching t/f ✔✔True
Drive isolation transformers cannot provide protection from common mode transients that
originate with the primary source t/f ✔✔False
Drive isolation transformers protect the primary source from common energies that originate
with motor drive system and can prevent ground current from transferring back through primary
ground system t/f ✔✔True
Match corresponding letter of the saturable core transformer ✔✔pg 159
, A ? is a distortion in a voltage waveform where the voltage quickly drops toward zero and then
returns to the correct value. ✔✔notch
The opposition to current flow that is only present in AC is ? . ✔✔reactance
A ? is an inductor whose inductance is controlled through the use of a magnetic field created by a
second winding wound around the same iron core as the primary winding. ✔✔saturable-core
ractor
Electric motors typically draw many times their full-load current during startup. ✔✔True
a reactor should have about ? impedance to reduce notch depth by about 50% ✔✔3%
All two-winding transformers are isolation transformers ✔✔True
? is a type of electromagnetic interference induced on power or communication lines
✔✔Common-mode noise
a ? is a reactor used to reduce common-mode noise current generated by the rapid switching of a
motor drive or a signaling device ✔✔Common-mode choke
