Apprentice > 4th Step Study Guide > Flashcards

4th Step Study Guide Flashcards

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1
Q

Definition of current?

A

The flow of electric charge caused by a difference in voltage.

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2
Q

Definition of resistance?

A

The opposition to the flow of current through a conductor due to the length and material.

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3
Q

Definition of reactance?

A

Opposes the flow of electrical current in an A/C circuit.

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4
Q

Definition of impedance?

A

The total opposition to the flow of A/C current due to the combined effect of capacitive and inductive reactance.

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5
Q

Definition of power?

A

The rate at which an electric circuit transfers electric energy.

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6
Q

What are the two types of reactance?

A

Inductive and capacitive

They are 180 degrees apart

Inductive reactance LAGS

Capacitive reactance LEADS

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7
Q

In a WYE bank are line and phase voltages the same or line and phase currents?

A

Line and phase currents are the same in a WYE bank.

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8
Q

In a Delta bank are line and phase voltages the same or line and phase currents?

A

Line and phase voltages are the same in a DELTA bank

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9
Q

What’s the the phase shift angle between inductive and capacitive reactance and voltage and current?

A

90 degrees

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10
Q

Definition of voltage?

A

Electric potential energy. The driving force for electrons through a circuit.

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11
Q

Wye wye connection advantages and disadvantages.

A

Wye wye you tie to the system neutral so in phase 3rd harmonics can flow.

Advantages:

  • provide a grounding point for ground fault protection
  • less insulation required at neutral ends due to reduced voltages.

Disadvantages:
- do not trap 3rd harmonics

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12
Q

Delta delta connections advantages and disadvantages.

A

Advantages:
- 3rd harmonics are trapped

Disadvantages:
- provide no common grounding point

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13
Q

Wye delta advantages.

A
  • 3rd harmonics are trapped

You must tie to system neutral anytime you energize or de-energize bank until you close the delta connection because they 3rd harmonics won’t be trapped until it’s closed.

You must un tie from system neutral after energizing because if you don’t you will turn the bank into a ground bank.

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14
Q

What are the 4 types of banks you can build with 4 wire?

A
  • Open delta
  • Closed delta
  • Wye
  • Open wye
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15
Q

What are the 2 banks you can build with grounded 3 wire?

A
  • Open delta corner grounded

- Closed delta corner grounded

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16
Q

What are the 3 banks you can build 3 wire no ground?

A
  • Open delta
  • Closed delta
  • Wye
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17
Q

Definition of Capacitance.

A

The property of a circuit that opposed any change of voltage in the circuit

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18
Q

What does a capacitor consist of?

A

2 metal plates that are parallel to one another and are separated by a dielectric.

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19
Q

How do you increase the capacitance in a capacitor?

A
  • The greater the area of the plates
  • The smaller the distance between the plates
  • the better the insulating value of the dielectric.
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20
Q

Why is there a resister inside the capacitor between the two terminals?

A

The resister provides a discharge path to bleed off the charge inside the capacitor after it has been de-energized.

The resister is high enough that it does not effect the capacitor when it is energized.

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21
Q

What is the in-phase condition called where current and voltage are exactly the same?

A

Unity power factor

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22
Q

What is it called when voltage and current are out of phase from each other by 90 degrees?

A

Reactive power

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23
Q

Power factor is either ______ , ______, or _______ determined by wether voltage and current are in phase.

A

Unity , leading, or lagging.

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24
Q

Formula to find power factor?

A

PF = real power (KW) \ apparent power (KVA)

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25
Inductive loads _______ VAR and cause a _______ in the system voltage.
Absorb VARs | Decrease system voltage.
26
Capacitive loads _______ VAR and cause ________ in system voltage.
Supply VAR increase in system voltage.
27
Formula to find full load amps on a cat bank?
Kvar x 1000 / line voltage x 1.73
28
Why must you not open the secondaries on a CT?
Because you could can create a high voltage and burn up the CT.
29
Kilowatt hour meters measures what?
Instantaneous real power flow (in-phase)
30
Kilovar-hour meters measure what?
Instantaneous reactive power flow (not in-phase)
31
What are the two basic types of voltage regulators?
1. Inductive voltage regulators | 2. Step voltages regulators.
32
What are the 4 R's?
1. Reads 2. Recloser - blocked 3. Regulators - blocked on step or neutral 4. Relays (ground relays) - blocked
33
In a 4kv circuit paralleling inside the feed point regulator should be set on?
Neutral and off control
34
In a 4kv circuit paralleling outside the feed point regulator should be set on?
On step and off control.
35
In a 4kv circuit paralleling inside the feed point how many amps can you break?
Maximum 50 amps
36
In a 4kv circuit paralleling outside the feed point how many amps can you break?
Maximum 75 amps.
37
Midpoint RCS should be placed where in the circuit?
Where you can sectionalize approximately 50% of the load on the circuit.
38
What are the 3 types of RCS's?
1. Midpoint RCS 2. Paralleling/tie RCS 3. Generation RCS
39
Each type of PE gear installation requires:
- Control mechanism - Transfer mechanism (switch) - Voltage - sensing units (pt's)
40
5 types of PE gear?
- PEO - PEA - PED - SS - SRL
41
What does a ground bank do?
A ground bank is a transformer bank that provides a source of ground current on a ungrounded delta system. - A ground bank stabilizes the neutral on a 4 wire distribution circuit by grounding the system (neutral no longer floating) • protects the customer from phase to neutral customer over voltage.
42
Should a ground detector bank be used when there is phase to neutral customer load?
No - A ground detector bank will not stabilize the neutral on a 4 wire circuit and will not protect from over voltage.
43
Definition of harmonics?
Harmonics are multiples of the fundamental frequency of a wave The electrical frequency is 60 hertz so harmonics are multiples of 60 hertz
44
Triplen harmonics are?
3rd, 9th, 15th etc multiples of 3. Odd numbers. Triplen harmonics are the most dominant
45
What happens when the harmonics can't flow?
You can not stabilize the voltage
46
Ferro occurs when?
When the magnetizing impedance of a transformer is placed in series with the capacitance to ground of the cable.
47
Ferro typically results in?
In high primary phase to ground voltages and low energy capacitive currents
48
The 4 conditions required to create a ferro condition?
1. phase to phase connections or wye connections with a floated neutral. 2. phases are energized or de-energized one phase at a time 3. Combined secondary load on radial is insignificant compared to the primary cable length being switched 4. If the primary cable will be de-energized or energized one phase at a time and the length of the cable is greater than or equal to the critical cable length.
49
A fuse is a thermal device with a fusible element designed to melt at a _________ within a ________
Specified current within a specified time ** 4th step book fuses of 2
50
What are the 2 time characteristics of a fuses?
1. The time required to melt a fuse element at a specific value of current 2. The time required to clear the current flow.
51
Fuses are installed on primary distribution circuits for what various reasons?
- Fault protection - Switching - Device isolation - Current limitation - Violent failure protection - Overload protection
52
Under fault conditions what are the 2 types of current flowing into a fault?
Symmetrical current Discharge current
53
What is it called when symmetrical current and discharge current add together?
Asymmetrical
54
Since a 60 hz system goes through zero voltage and zero current _____ times per second the arc is being reignited _______ 120 times per second.
120 per second 120 per second
55
What does an inverse time current characteristic mean?
The higher the fault current the quicker it will isolate the fault.
56
There are basically three fuse designs:
1. Expulsion type 2. Non-expulsion type 3. Current limiting type
57
An explosion fuse is a ___ ____ _____ because it waits for the passing of the current through _____ to ______ the contained arc and clear the circuit.
Zero awaiting device, zero to extinguish
58
An expulsion fuse requires at least _____ ______ ______ before it can clear the fault
One half cycle
59
Summary of expulsion fuses:
- Relatively inexpensive - Lower interrupting - Non current limiting - Sensitivity to recover voltage - Loud intense interruption - Expelled hot gases molten debris and other expulsion byproducts
60
What are the four reasons to bypass an AR?
- Closing the AR's bypass switch for any reason - Changing the status of the circuit ( changing the length of the line ) parallels, box loops, etc - Working on the high side of an AR for maintenance, removing debris - The AR is inoperative
61
Why are RAR's installed on the Edison system?
- Sectionalize :because the setting at the sub ( P-P and P-G) are set to high to clear a fault down the line - Protection :problematic circuits like trees, wind, mountain etc. - Change mode of operation : SOB 322 high fire areas
62
What are five reasons a RAR may open?
- Phase to ground fault ( escaping current ) - Phase overload - phase to phase - paralleling - Box loop
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