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