General Knowledge Flashcards
Explain what backfeed is?
Voltage supplied from load side
3 things that must be checked when given a pair of rubber gloves?
Voltage rating
Inspection
Test date
What is the purpose of a stress cone?
To prevent voltage stress at semi con edge, spread stress out across larger area
Explain the process of properly using phasing sticks?
-Verify both circuits are energized
- verify phasing equipment works properly
- phase across open
What is the purpose of static/shield wire?
To protect system below by attracting lightning to itself.
What could happen if grounds were removed from a single bushing TX?
TX case could become energized to full phase voltage
Explain the purpose of concentric wire?
Reduces/ spreads out voltage stress that leaks through insulation. Acts as a neutral returning unbalanced load back to source
What’s the advantage to a Y secondary connection ?
1). More efficient
2). Balanced load
What is the purpose of an iron core within a TX?
To direct and channel magnetic field
Class 4 rubber gloves (color ID and max use voltage)
Orange
36,000
Class 3 rubber gloves (color ID and max voltage use)
Green
26,500
Class 2 rubber gloves (color ID and max voltage use)
Yellow
17,000
Class 1 rubber gloves (color ID and max voltage use)
White
7,500v
Class 0 rubber gloves ( color ID and max voltage use)
Red
1000v
How often are rubber gloves tested?
Every 6 months
How often are rubber sleeves tested?
Annually
Class E hard hat voltage rating?
20,000v
What is power factor?
Ratio of true power to apparent power
KW:KVA
4 ways for cooling TX
Fins, fans, air, oil
3 type of capacitors
Time, temp, fixed
Carbon in transformer oil indicates what?
Arcing
3 parts of a rope
Fibers, yarns, strands
IBEW history
First president:______
Year formed:______
City formed in:_______
Henry Miller
1890
St. Louis
What is PCB?
Poly chlorinated biphenyl
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
What does SF6 stand for?
What does it do?
Silver-hexafloride
Dense arc snuffing gas
You can rubber glove a maximum of ___ volts phase to phase off the pole without an insulated platform
5 KV
How do you verify a pole is safe to climb?
Visual inspection
Sound test
Bore test
What is the purpose of armor rod?
Reinforce conductor
Reduce chafing
3 considerations when sagging conductor?
Temperature
Span length
Size of conductor
4 steps to grounding a line?
Identify
De-energize
Test
Ground
What is the speed of light?
186,282 miles per second
It’s important to make Neutral connections first and break last to prevent __________________?
Severe voltage fluctuations in the service
Formula for calculating KVA?
E x I / 1,000
What is a capacitor and what does it do?
Two conductors separated by a di-electric material
- it corrects power factor
____________ are connected in parallel to improve power factor
Shunt capacitors
Transformers larger than ____ KVA have four secondary bushings
100 KVA
What is a bowline rated for?
65% of the rope’s strength
Ratings:
Knots
Hitches
Splices
50%
75%
85%
What does the emergency control handle on a CSP do?
Increases full load capacity temporarily
What is most power generated at?
13,800
Four characteristics of a CSP?
- Externally mounted arrestor
- Internal primary fuse link
- Secondary breaker
- Overload indication light
What does SF6 stand for? What does it do?
Sulfur Hexafloride
A dense arc snuffing gas
If a nameplate shows “Grd” along with the primary voltage ____________?
Single bushing
H2 must be connected to system neutral
A TX used to reduce voltage to a safe working level for purpose of metering and checking primary voltage accurately, connected in parallel
PT
Total opposition to current flow in an AC circuit, measured in ohms
Impedance
Capacitors have an ____________ that will reduce the voltage to 50 volts or less within 5 min
Internal discharge resistor
What 3 physical dimensions determine pole classification?
Length, circumference 6’ from bottom, circumference of pole top
Why do we transpose transmission lines?
To balance the line electrically and reduce radio noise
What does a stress cone do?
Relieves electrical stress at point of termination
When a line is de-energized what kind of opening is considered safe?
Visual open
What 3 things should you check on a mechanical jumper?
Clean tight connections, insulation value, ampacity of wire
What is the purpose of a distribution TX?
To reduce primary voltage to a usable voltage for the customer
Name 3 factors to take into consideration when sagging conductor.
Temperature, span length, size of conductor
What’s the purpose of a damper?
Limit vibration of the conductor
What’s the purpose of armor rod?
Reinforce conductor and reduce chafing
Why are cases of TX’s, circuit breakers, regulators etc. grounded?
Protection of public, workers, and equipment
Process of de-energizing a capacitor
-Load break disconnects open
-Wait 5 min for discharge resistor to drain capacitance
-shunt bushings
What are capacitors equipped with to drain capacitance?
Internal discharge resistor
Why isn’t DC used for distribution?
Can not be transformed for one voltage to another easily
How often should rubber gloves be inspected?
Before each use
When are fault indicators activated?
Over currant situations
Two design purposes of a fused cutout?
- Protect equipment from over load
- Isolate faulted equipment before upstream protection opens
What does a regulator do?
A regulator corrects variations in voltage by adding or reducing turns to the primary coil in small incremental steps
2 types of lightning arrestors
Valve type
Expulsion type
What’s the purpose of bundling conductors?
To cut down on corona loss and increase current carrying capacity
What is corona?
Discharge of ionized particles
What’s the function of lightning arrestors?
To create a path for voltage surges to be dissipated to ground before harming equipment
What precautions should be taken before working in a manhole?
-barricade the public
-expel harmful gasses
-competent observer
-rescue system
How many watts equal on Horsepower
746 watts
On a Wye-Delta closed bank, what type of TX must be used?
Two bushing TXs
What is an LTC?
Load Tap Changer
4 foot rule for excavation
And exit must be provided within 25’ if trench is 4’ or deeper
What is an auto transformer?
A TX who’s primary and secondary have a common winding
3 factors to take into consideration when sagging conductor
Temperature, span length, size of conductor
What’s the purpose of a damper?
Limit vibration of the conductor
3 ways of classifying a pole safe to climb
Visual inspection, sound inspection, bore test
What is a generator?
A device that converts mechanical energy to electrical power
Three most important things to consider on a nameplate ?
Voltage, impedance, and polarity
