Transformers II Flashcards
VFD’s are a source of ? Noise.
Select One:
A) Loud
B) Very little
C) Common-Mode
D) False
C
A drive Isolation transformer is designed with additional ? to reduce the current though the motor winding and reducing the load on the power distribution circuit during motor starting.
Select One:
A) Inductance
B) Reactance
C) Capacitance
D) Eddy Current
B
An autotransformer used for reduced-voltage motor starting is a method of reducing the current through the motor winding and reducing the load on the power distribution circuit during motor starting?
Select One:
True
False
True
? help eliminate voltage spikes by slowing down the rate of change in the drive output voltage.
Select one:
a.
Drive isolation transformers
b.
Output reactors
c.
Output rectifiers
d.
Variable-frequency drives
B
Which of the following are benefits associated with grounding the secondary of a drive isolation transformer?
I. Grounding provides superior transient and impulse immunity to the load side of the transformer.
II. Grounding reduces common-mode noise coupling from primary to secondary.
III. Grounding prevents induced ground current from transferring upstream into the primary system.
IV. Grounding will reduce the total harmonic distortion in the primary of the system.
Select one:
a.
I. and II. only
b.
I., II., and III. only
c.
I., II., III., and IV.
d.
II. and III. only
e.
III. and IV. only
B
A ? is a coil added in series with a load to reduce inrush current, voltage notching effects, and voltage spikes.
Select one:
a.
capacitor
b.
polarized-frequency relay
c.
reactor
d.
silicon-controlled rectifier
C
A(n) ? transformer is a continuously adjustable autotransformer consisting of a single layer of wire wound on a toroidal core, and a carbon brush that traverses this winding.
Select one:
a.
autoadjusting
b.
autotoroidal
c.
combination
d.
variable
D
Buck-boost transformers are typically available in sizes up to ? .
Select one:
a.
0.1 kVA
b.
1 kVA
c.
10 kVA
d.
112-1/2 kVA
C
Buck-boost transformers can be wired with subtractive polarity to buck the source voltage.
Select one:
True
False
True
For buck-boost transformers, the NEC® makes a distinction between those rated at less than ? and those rated at that amount of current or more.
Select one:
a.
9 A
b.
10 A
c.
11 A
d.
12 A
A
