問題一覧
1
The voltage to ground on a “high leg” is Volts
208
2
Normally, the power factor of an incandescent lighting circuit is
1.0
3
What is the phase angle relationship of current and voltage in a pure resistive circuit?
They are in phase
4
Frequency is measured in
hertz
5
The charge of a capacitor is expressed in
Coulombs
6
To find effective voltage value you would
multiply the maximum voltage value by 0.707
7
One cycle of a 60 Hz system would be completed after
1/60 of a second
8
If a current voltage are in phase, the AC circuit would
Be operating a totally resistive load
9
The inductive effects on a circuit are explained by
Lenz law
10
A microfarad is equal to
1 millionth of a farad
11
The primary and secondary windings of a single phase transformer are
Not physically connected
12
To find the phase angle when the power factor is known, what trigonometric function do you use?
Cosine
13
The ASA standard for step down transformer leads is
“H” for primary and “X” for secondary
14
If line 1 of a 3-wire system has a 25a load in line 2 has a 5a load. What is the current on the neutral?
20 Amps
15
A 208/120 V 4-wire system would be derived from a/an
wye transformer
16
Power companies are interested in providing the power factor to
Reduce line current
17
A power factor of 1.0 exist only when the
Current voltage are in phase
18
Voltage is induced in a conductor when
When it cuts through magnetic flux lines
19
Peak voltage is derived by
A conductor cutting lines of flux at 90° and 270°
20
What is the formula for total VA in a wye system?
3 X Vcoil X Icoil
21
If you were asked to spot values on a sign wave at different angle values, you would be plotting the Values
instantaneous
22
The neutral conductor carries the Load of a 3-wire or 4-wire system
Unbalanced
23
The core of an inductor coil may be made of
Soft iron
24
Removing the laminated iron core from a coil in an AC circuit will The inductive resistance in the circuit
Decrease
25
Any quantity having both magnitude and direction is graphically represented by a
Vector
26
A capacitor consists of two plates of conducting material separated by a/an
Dielectric
27
The Of a material determines its insulating quality
Dielectric
28
In the triangle shown you would solve for “C” with the following formula
C= \/A2+B2
29
The actual sum of 2 vector quantities that are traveling in different directions is called the
Resultant
30
The electrical symbol “Z” represents
Total opposition to current flow in an AC circuit
31
A transformer has
No moving parts
32
The voltage and the number of turns in a transformer winding are
Directly proportional
33
Items to be Considered that will reduce the efficiency of a transformer are
All of these losses
34
The neutral should be In a single phase or 3 phase system
Grounded
35
Transformers are rated in Capacity
VA or KVA
36
As a general rule, the neutral conductor should Be fused or broken at any switch or control point
Never
37
Any quantity having both magnitude and direction is graphically represented by a
Vector
38
What is the phase angle relationship of current and voltage in a pure capacitive circuit?
current leads the voltage by 90°
39
In a circuit containing pure inductance
current lags voltage by 90°
40
AC voltage is generated by a conductor
Rotating through a magnetic field
41
In a purely capacitive AC circuit, the current The voltage by Degrees
Leads, 90
42
A “High leg” is found in a system
Delta
43
What is the phase angle relationship of current and voltage in a pure inductive circuit?
current lags the voltage by 90 degrees
44
Inductance is measured in
henrys
45
Inductive reactance is measured in
ohms
46
Capacitance is measured in
Farads