Step 6 Flashcards
Why is the square root of 2 (1.414) important to remember?
For rigging vectors.
What is the difference between a switched and fixed capacitor bank?
Switched capacitors banks can be energized on a given schedule determined by :time ,temp,load, voltage, or other.
What is pass to neutral voltage of 12,460 volt feeder?
7,200 V.
Can an apprentice hold a steward position on the job.
No
3 items to check on a mac jumper
- Current carrying capacity
- Condition of insulation
- Condition & size of the connectors on the jumper, for good mechanical use
What is the rated secondary voltage of transformer needed to produce three phase 120/208 V
120V
List steps necessary to properly phase the secondary of two 480V three phase bank
- Check relative polarity
- connect the high side of the second bank and energize
- Connect one secondary leads to the common point and with a voltmeter check the other conductor.
- A zero reading on the voltmeter will allow the banks to be connected.
- GR’s
Define impedance.
The total opposition to the flow of current in an AC circuit
Explain how to test a transformer for additive or subtractive polarity>
Connect 120 on h1 & h2, put a jumper on h1 to x1,put a voltmeter from h2 to x2 if it reads more its additive if it reads less than applied voltage then its subtractive.
In relationship to the load where is the optimum location to hang a capacitor bank.
As close to the load as possible.
Explain how to load check 3 phase transformer bank
by using a amp meter
Can you work bonding on a 33 KV circuit with rubber gloves.
No
Before any work is to be done with rubber gloves a complete tailboard will to insure that all personal are aware of the work and associated hazards.
True
It shall be mandatory that sleeves of the same voltage rating as the rubber gloves to be worn when working on energized conductor of apparatus above 7,500V Phase to phase
True
What is the purpose of disconnect switch?
To isolate a line or apparatus form an energized circuit.
What is the function of an automatic recloser?
To interrupt and reclose on a circuit automatically to clear transient faults
What is the safe working distance from conductors energized at?
7,500-15,000 V 2’1”
15,000-35,000 V 2’4”
While live line work is in progress no other work of any nature shall be performed?
True
What is the maximum resistance a ground should have?
25 ohms
Why is semi-conductor used on underground cable?
To equalize stress on the cable insulation
You are going to parallel two circuits of the same voltage feeding from the same substation what must you do to any regulators on the line?
The regulators must be placed on neutral and locked out.
How much clearance is required between guys and conductors supported on the same pole?
120/240 3”
4KV 6”
12KV 9”
If the neutral of a 4 wire 12KV circuit was broken or disconnected why precaution would you thane when making repair?
Treat as a 12KV primary phase, mac it out using hot sticks then either work it with hot sticks or tubber gloves.
Explain the procedures for replacing a broken 12KV insulator on a bonded arm with circuit energized
you place cover where needed and you cut the bond from the insulator and change out the insulator
What is the propose of a pilot wire?
Circuit protection and street light circuit
Can a Foreman work when energized work is being performed 600V or more by members of his/her crew?
NO
Explain how to take a clearance on a line?
you call systems and ask them to give you clearance on the line you want and place your tag on it
List three conditions that would cause induced voltage on a line?
- Wind static
- Lightning strike
- Transmission lines
On a three phase, 4 wire delta secondary (240) volts, the voltage taken from each phase to neutral would be
120V, 120V, 208V
Can 400 Amps of current be dropped on a 400 Amps KPF switch?
No
A 500 KVA transformer has a primary voltage rating of 7,200V a secondary voltage of 240V
I=KVA1,000/E
1. I=50,000/7,200 =6.94 full load primary current
I=KVA1,000/240
2. I=50,000/240 =208.33 Amps full load secondary current
A 2,500 KVA transformer bankis connected to 13.2 KV feeder what will be the feeder current with the transformer fully loaded?
I= KVA1,000/1.73E
I=2,5001,000/1.7313,200 =109.48 Amps
Precautions taken before work on confined space
Atmospheric test, ventilation, heat scanner check
In a confined space
Employee present, traffic control, warning devises
