General Knowledge Flashcards
What is the purpose of an iron core within a TX?
To direct and channel the magnetic field
How do you find full load rating of a TX?
Full load rating=KVA/ sec voltage
I=P/E
Core loss in a TX comes from_________ set up by the constant reverssing of the magnetic field
Eddy currant losses
Copper loss in a TX is due to the ______ of the windings
Resistance
What is corona ?
Alluminous discharge of ionized particles
An electrical device that allows currant to flow only in one direction
Diode
Voltage read on a meter before it is connected to an electrical circuit produced by magnetic field
Ghost voltage
A ____________ is a temporary undesirable voltage in an electrical circuit
Transient voltage
An explosion that occurs when the air surrounding electrical equipment becomes ionized and conductive
Arc blast
A system that has a common connection for all three windings is ________ connected
Wye
Windings and three phase generation are _______ apart
120’
What is a capacitor, what does it do?
Two conductors separated by a di-electric material
Used to balance power factor
The _________ voltage value is measured from zero to the highest value obtained in either direction
Peak
What is the speed of light?
186, 282 miles/second
The time required for one cycle is called the ______?
Period
Formula: length of guy estimate
Height of attachmentment above ground + 1/2 distance pole to anchor
Formula: Guy tension
Line tension x (length of guy/distance to anchor)
Formula: structure tension
Distance from adjacent structure to adjacent structure x conductor weight per thousand ft/ 2
____________ are connected in parallel to improve power factor
Shunt capacitors
If a transformer with no connected load is energized, the exciting current may be as high as ______ of the transformer full load current
5%
Where does the potentially lethal third harmonic voltage come from
The difference between primary and secondary neutrals if the two are not connected
Transformers that have a rating over ______kVA or primary voltage over ______ are subtractive
200 KVA
8600 volts
5 musts for parralleling transformers
- Identical voltage ratings
- Identical tap settings
- Identical frequency ratings
- Impedance + or - 7.5
- Tapped on the same phase
The primary coil in a dual voltage transformer(clicker) can be connected in ________ or________ depending on incoming voltage
Series or parallel
Definition of a nuetral
A current carrying conductor at ground potential that acts as a return for unbalanced load
Definition of a transformer
A transformer is a ratio in device operating on the principal of mutual induction
A CSP primary lead should be taken off-line before working the secondary because?
The secondary coil might have enough capacitance to hold a charge
No visual open
The emergency control handle on a CSP should be used as a _______[?
Temporary fix to an overload situation
The primary fuse link of a CSP protects ______ from an internal fault
The system
If the nameplate conveys the secondary 240/120 or 208/120 what does that mean 
The coils are permanently connected in center tap series, can not be connected in parallel
If the nameplate coveys the secondary 120/240 what does that mean
Means the coil can be connected in series, parallel, or center tapped series
What does it mean if there is a slash (/) between primary voltages on the transformers nameplate
Both H1 and H2 are insulated
Suitable for delta connection 
If the name plate has an X between the listed voltages what does that mean?
The coil may be connected in series or parallel but never center tapped
If the nameplate has “Grd” along with the primary voltage the transformer ____?
Single bushing
H2 must be connected to system nuetral
Class II gloves
Tested: _______
Rated: ________
Color: ________
Tested: 20,000 v
Rated: 17,000 v
Color: Yellow
Class III ruber gloves
Tested: ______
Rated: _______
Color:______
Tested: 30,000 v
Rated : 26,500 v
Color: Red
Class IV rubber
Tested: ______
Rated:_______
Tested: 40,000 v
Rated: 36,000 v
Angular displacement
Y-Y: ________
Y-delta:_______
Y-Y: 0, 180 degrees
Y-delta: 30’ (sub) , 210’ (add)
IBEW history
First president:______
Year formed:______
City formed in:_______
Henry Miller
1890
St. Louis
Minimum approach distance phase to phase
1-15 kv= _____
15-36 kv=_____
NWE
27”
33”
How do you field test for polarity?
1) energize H1 at 120 V
2) Connect jumper from H1 to adjacent secondary bushing
3) Measure between H2 and it’s adjacent secondary bushing
If voltage is greater than 120 its additive, less than 120 its subtractive 
How does an open delta bank share load?
3{}
1{}
Power pot Lighter pot
3{} Equally @ 57.7% of total KVA
1{} 100%
How does a close Delta Bank share load?
3{}
1{}

3{} 1/3 each
1{} power pot 1/3 each
Lighter pot 2/3
How does a closed Y Bank share load?
3{} 1/3 each
1{} 1/3 each
What is power factor?
The ratio of true power(watts) to that of aparent power(volt amps) or
Total current to useful working current
What is a PT?
Transformer used to reduce voltage to a safe measurable level for purpose of metering and checking primary voltage accurately
PT-Parallel 
What is transposition?
When all three phases change position to cancel excess induction that interfere with open wire telephone circuits
What is a CT?
A transformer that reduces current to a measurable value for metering
CT-Series
What does SF6 stand for?
What does it do?
Sulfer hexafluoride
A non conducting gas
What does a transformer fuse protect against?
What are two design purposes?
Over currant
1. Protect our equipment from over load
2. Isolate faulted TX before upstream protection opens
What does an emergency control handle on a CSP do?
Increases full load capability temporary
Four functions of a CSP transformer?
- Externally mounted arrester
- internal primary fuse link
- secondary breaker
- overload indication light
What is most power generated at?
13,800- 24,000
ratings
Knots:
Hitches:
Splices:
50%
75%
85%
What is a bowline rated for?
65%
Three parts of a rope?
Fibers, yarn, strands
Lowering a tap _______ customer voltage
Raises
-less primary windings
-lower turns ratio
Raising a tap _______ customer voltage
Lowers
- more primary windings , increases turns ratio
What does a regulator do?
A regulator corrects variations of voltage by steping up or down in small incremental steps by adding or reducing turns to the primary coil
The conductivity of aluminum is about ____% that if copper
62
What is the max amount of stretch a overhead lifting chain can have?
3%
Two types faults in an electrical system?
Short circuit and open circuit
A distrobution system is exposed to what three faults?
Over-currant, over-voltage, and open circuit
When are Fault indicators activated?
Over currant situation
Purpose of a stress cone/pothead?
To distribute voltage stress over a larger area, reducing stress at semi-con edge
What is PCB
Polychlorinated biphenyl
Transformers larger than ____ KVA have four secondary bushings
100 KVA
Open Wye-Open delta bank efficiency rating
86.6% of the two TX
A __________ is a slave device that cannot interrupt fault currant, and opens during a specified interval of recloser operation
Sectionalizer
What is the efficiency rating of a Wye Delta open bank?
86.6% of the total KVA of the two TX
What is the efficiency rating of a Y-Delta bank if it has been converted from closed to open?
57.7% of the original closed bank
Or 86.6% of the remaining two TX
What is SCADA?
Supervisory control and data acquisition
On a three phase Y-Y pad mount, the three primary coils and secondary coils share what?
Common core
