4th step SSQ Flashcards
1
Q
- What is the equation for determining a transformer’s turns ratio?
A
Np- Number of turns on the primary
Ns- Number of turns on the secondary
Vp- Voltage on primary
Vs- Voltage on secondary
Reference: 2nd step transformer theory and design
2
Q
- Determine the turns ratios for the following single-phase transformers.
a. 16 kV to 120 V
b. 16 kV to 240 V
C 12 kV to 120V
d. 12 kV to 240V
A
A.133:1
b.66:1
C.100:1
d.50:1
Reference: 2nd step transformer theory and design
3
Q
What are the two polarities a transformer can have?
A
Additive and subtractive.
Single-phase transformer nameplates indicate whether its polarity is additive or subtractive. Polarity indicates the relative direction of current flow through the transformer. Polarity is determined by looking at the “polarity bushing” (H1) on the transformer, and its relation to the X1 bushing. When H1 and X1 are on the same side, it is considered subtractive polarity. When H1 and X1 are on opposite sides, it is considered additive polarity. With standard markings, if the direction of current flow is from H1 to H2, the current flow will be in the direction of X2 to X1.
Reference: 2nd step transformer polarity
4
Q
What is the purpose of a transformer tap changer?
A
To raise or lower secondary voltage by changing the turns ratio
Taps on transformers allow the turns ratio to be changed over a small range. This gives some flexibility for adjusting the operating voltage of the transformer. Each tap changes the turns ratio by some small amount, typically 2.5%. The taps consist of terminals, linkages or similar devices.There are two types of tap changers: no load tap changer and load tap changer. No load tap changers require the transformer to be de-energized, so there is a short interruption in customer service while the taps are changed. Load tap changers provide the ability to change taps while the transformer is energized and without interrupting the flow of current through the transformer and to the customer.
Reference: 2nd step Transformer Design and Theory
5
Q
How is rotation checked/determined?
A
At the customers panel using a phase sequence indicator, from L to R (RWB) attach clips to customer’s phases.
Reference: 4th Step Vectoring Training Manual
6
Q
What is the maximum weight allowable for a closed-delta 300 kVA transformer bank on a 50-foot wood pole using a transformer mounting bracket? What is the minimum diameter pole for this application?
A
4,250 Ibs.
H2 class
11 inch minimum diameter.
Reference: DAP Table AP 106-1, and AP 132-1 Note 7
7
Q
What is the maximum weight allowable for a 2-single phase transformer bank (open delta) hung on a wood pole using a transformer bracket?
A
1,600 Ib total weight limit.
Reference: DOH, Figure AP 122-1
8
Q
Describe the AC electrical characteristic of impedance.
A
Impedance opposes the flow of electrical current in an AC circuit. It is made up of two components: resistance and reactance. Since reactance is at a 90-degree angle to resistance, resistance and reactance are added with vectors in order to calculate impedance.
Reference: 4th Step Ohm’s Law and Power Formulas Training Manual
9
Q
When - and why - is the wye leg tied, on the primary side of a 4 kV bank?
A
Open Wye banks (2 transformers) shall be connected to the system neutral.
Closed Wye- delta banks (3 transformers) - Wye-Delta you float
shall not be connected to the system neutral. When wiring a delta secondary, the delta is left open to check that voltage is less than 20 volts. Recall that a disadvantage of wye-wye connected transformers is that they do not trap third harmonics. Therefore, the wye must be connected to the neutral until the delta voltage is checked and then the delta is closed to provide a path to circulate the 3rd harmonic currents. After the delta is closed, the wye connection is floated
Tied for checking voltage.
Wye- Wye banks (3 transformers) Wye-Wye you tie
A disadvantage of wye-wye connected transformers is that they do not trap third harmonics. This will be discussed in more detail in the Voltage Problems training module. Because all harmonic voltages are in-phase, it results in phase currents that do not cancel in a wye. Therefore, there is no path for the 3rd harmonic currents when the wye is floated When the wye point is connected to the system neutral, it provides a path for the in-phase 3rd harmonic currents. Because these currents are additive, they add and can cause high unnecessary neutral currents
It is tied to get rid of the third harmonics
Reference: 2nd step transformer delta vs wye
10
Q
What is a high leg? How is it identified?
A
A high leg is the secondary phase with the highest phase to ground voltage.As required by the National Electric Code, the high phase (power leg) must be prominently identified by orange markings on the cable or bus.
Reference: DOH, T 454 Note 4
11
Q
In a three-phase circuit, what is a grounded leg? Where is it located in the customer’s panel?
A
A grounded leg is a phase that has been grounded. It is generally located in the middle position in the customer’s panel.
12
Q
When and why is rotation checked?
A
The need for a phase sequence meter is to identify the rotation of a three phase source and to ensure that the equipment can be reconnected to the source with the proper rotation. Before taking a piece of equipment out of service, the rotation should be checked and recorded. Then, after the work has been completed, the rotation should be rechecked before the equipment is re-energized.
Reference: 4’ Step Vectoring Training Manual
13
Q
How is improper rotation corrected
A
Without disturbing the high-leg, swap any two phases.
Reference: 4’ Step Vectoring Training Manual
14
Q
If two 10 kVA transformers are wired in an open-delta configuration - for 3-phase power - what would be the available kVA?
A
20 kVA x0.86 = 17.2 available kVA.
Reference: 4’ Step Wiring Three-Phase Banks Training Manual
15
Q
What are the thumb rules for determining amps per kVA for the following secondary voltages?
A
a. 120 V single-phase
b. 240 V single-phase
480 V single-phase
d. 240 V three-phase
e.480 V three-phase
f.208 V three-phase
a. x8
b. x4
c. x2
d. x2.4
e. x1.2
f. x 2.8
Reference: pocket manual
16
Q
What is TS-5, and when is it used?
A
2.1 Applicability
This procedure shall be used to field-test all newly installed and relocated overhead transformers, and all overhead transformers with blown fuses.
1.0 purpose
This procedure outlines the requirements for in-place field-testing of overhead transformers. It is to be used for:
* Newly installed or relocated transformers
* Re-energizing existing transformers with blown fuses
* CP transformers with tripped overload breakers
Reference: DOM, TS-5 1.0
17
Q
When applying TS-5 to newly installed/relocated transformers, how are the transformer secondaries grounded (prior to energization).
A
For grounded secondaries, connect the secondary ground. For ungrounded secondaries, temporarily install a solid ground on the low side at any of the phase connections or the neutral. (The intent is to ensure enough fault-current to blow the test fuse for a primary to secondary fault.)
Reference: DOM, TS-5 4.1
Distribution Apprentice Lineman OJT
18
Q
When are clearances required?
A
Clearances are required to work on de-energized generating station or substation apparatus or equipment which is normally energized above 600 volts.
Clearances are required to work on de-energized lines or line sections above 600 volts.
Reference: APM Rule 105
19
Q
When are no-test orders required?
A
No Test Orders (definition DOM)
For hazardous line construction work, Edison makes available “No Test Orders” (NTO) to every foreman. Once NTO’s are issued, if the line relays, it will not be tested until contact is made with the foreman they were issued to and he cancels his NTO
DOM SOB 314
A No Test Order is a formal statement issued and recorded under a prescribed procedure, by an authorized person to a qualified person, declaring that in case certain specified energized distribution line(s) or substation equipment of 33 kV or below become de-energized, said equipment shall not be re-energized, by any method, until the No Test Order has been released by the person to whom the No Test Order was issued.
The purpose of the No Test Order is to provide a formal procedure by which a qualified person could request and receive a guarantee that a line or equipment shall not be re-energized when the nature of the work is such that the re-energizing would be hazardous to personnel.
APM 233-No Test Orders shall be taken during Distribution arc flash hazardous work activities that could cause an Arc Flash when either working at MAD or within the Arc Flash Boundary (AFB). When performing Rubber Gloving or Hot Sticking
Reference: SOB 314 and APM Rule 233
20
Q
Why is it important that the correct size fuse be used in distribution circuits? What could result from installing a fuse that is either too weak or too heavy?
A
Fuses which are too weak may blow out during normal operating current loads. Fuses which are too heavy may fail to protect associated transformers (or other equipment).
Reference: 4thStep Fuses Theory and Operation Training Manual
21
Q
What are current transformers (CTs) and potential transformers (PTs)? What are their typical applications in distribution circuits?
A
CTs are transformers which reduce high currents to safe levels for relay protection and metering services.
PTs are transformers which reduce high voltage levels to safe levels for equipment operation and metering services.
Reference: 4th Step Metering Theory and Operation Training Manual
22
Q
How is a PT typically connected in a 2400 V application, and what is the typical turns ratio for this PT?
A
2400 V PTs are normally phase-to-ground connected.
The typical turns ratio is 20:1.
Reference: 4th Step Metering Theory and Operation Training Manual
23
Q
What is the load on the following transformer (120/240 V, 10), given the following data:
A
VA = IxE
VA = (20 A +30 A) x 120 V = 6000 VA or 6 kVA.
Reference: 4th Step V, I, and P Relationships Training Manual
24
Q
What is the load on the following transformer bank (120/240 V, 30), given the following data:
A
VA=I x E x 1.73
VA= 117A x 240V x 1.73
VA= 48,636
kVA=48.6
Reference: 4’ Step V, I, and P Relationships Training Manual
25
What is the equation for determining the load on a transformer bank with unbalanced loads?
VA=[(IA+IB+IC)/3] x E x 1.73
Reference: 4th Step V, I, and P Relationships Training Manual
26
Are pole-mounted grounds allowed in the climbing space? If so, what provisions must be observed?
2.4-one vertical run of PGW is allowed in the climbing space without the use of wood molding
3.3-Only one wood-covered ground wire is permitted in the climbing space.
Reference: DOH, GR 100.2.4 and 100.3.3
27
Are pole-mounted grounds allowed in the climbing space of rack construction?
No. Only one wood-covered ground wire is permitted in the climbing space. In rack construction, grounds are not permitted in the climbing space per G.O. 95, Rule 54.9-F.
Reference: DOH, GR 100.3.3
28
28. What is the safe working load limit of a 1-1/8" 2-in-1 double braid polyester core and cover winch line?
7.000 Ibs
Reference: Rigging Standards Manual, Table 11
28
29. What is the working load limit of a handline sheave?
1,000 Ibs
Reference: Rigging Manual, Figure RM 4-8
29
When using a hand hoist, is it acceptable to use the chain and hook in a choker configuration? Why or why not?
No. The hook will break under stress.
Reference: Rigging Standards Manual, Figure 147
30
31. What are the three basic nylon sling hitches?
Straight Pull
Choker Hitch
Basket Hitch
Reference: Rigging Manual, Figure RM 7-2
31
If a lineman has any doubt regarding the type or size of rigging equipment for a lift what should they do?
Contact their supervisor.
Reference: Rigging Manual, Making Lifts 8.2.
32
For what circumstance are pole grounds butt-wrapped on the pole? How is this accomplished?
Use in rocky soil where it would be impossible to drive ground rods.
Use PGW wire with 10' of protective covering removed (or bare wire) on bottom of pole, and staple in place.
Reference: DOH, Figure GR 105-1
33
What is the maximum tank temperature for a transformer?
By design, the maximum internal temperature rise in a transformer at full load can be 115 °F (65 °C); this can increase to a 155 °F (88 °C) rise at 160 percent of rated load. Under no circumstances should the maximum tank temperature (ambient plus tank temperature rise) exceed 265 °F (130 °C).
Reference: DOM, TE-5 4.1 Table 5-1
34
What activities are prohibited when working from a boatswain chair suspended from a fiber rope?
Welding, burning, or sandblasting
Reference: APM Rule 130.h
35
When making a lift with tackle blocks, how is friction accounted for?
The rigging industry recognizes a 10% friction factor for each sheave in any given rigging scenario.
Reference: Rigging Manual, 5.1.3.A
37. What does the term "wind loading" mean? What are the wind standard wind load values used by SCE?
Wind loading refers to the pressure - in pounds per foot (lb/ft) - exerted on poles. The standard wind loading value is 8 lb/ft, while 6 Ib/ft, 12 lb/ft, and 18 Ib/ft are also used.
Reference: DDS-10. 5.2
36
What does the term "wind loading" mean? What are the wind standard wind load values used by SCE?
Wind loading refers to the pressure - in pounds per foot (lb/ft) - exerted on poles. The standard wind loading value is 8 lb/ft, while 6 Ib/ft, 12 lb/ft, and 18 Ib/ft are also used.
Reference: DDS-10. 5.2
36
How often is MSA Altair gas analyzer calibrated? How often are functional tests performed?
The gas monitor shall be calibrated within 30 days prior to being used.
The accuracy of the instrument must be functionally checked with a known concentration of gas before each day's use. This is referred to as a "bump test." This is accomplished by applying calibration gas to the monitor until all sensors alarm
Reference: DOM, TE-13 2.2, 2.3
37
. If bayonet fuses must be used to de-energize a fused PM transformer, what is the maximum amperage that can be dropped? How is the load determined?
If a transformer is to be de-energized using the BON fuses, verify that the amperes through each BON fuse is not in excess of 100 A. Measure the primary current to the transformer. Measure the primary current feeding through the transformer to other load (if applicable). Subtract the feed through current from the current to the transformer. If this is less than 100 A, then the BON fuses may be used to de-energize the loads.
Reference: DOM, TR-2 Attachment 2-5 step 2
38
May PMHs or PMEs be used to de-energize capacitor banks? Explain?
PMH and PME switches cannot be used for capacitor switching. A sign reading "Capacitor Bank No. Source-Open Capacitor Bank Switch Before Opening This Switch" shall be placed on the compartment door of all PMH/PME switches used to feed capacitor banks.
Reference: DOM, SW-6 2.1
39
. Concerning riser construction: no step or kick block shall be installed below what height on a pole?
4. See DOH PO 100.4 for pole step requirements. No step or kicker block should be placed below the 9 foot level.
Reference: DUG, Figure CR 110-1 Note 4
40
When should the automatic circuit recloser be made non-automatic in underground distribution circuits?
316. Automatic Circuit Recloser Operation
a. No test orders will be taken on all circuits in an underground structure whenever the following work activities will be performed:
1. Testing, grounding, cutting, spiking, repairing cable or components normally energized above
600 V.
2. Disassembling cable components normally energized above 600 V.
3. Installing or removing electrical or communication cable.
4. Relocating energized high-voltage underground cable or equipment.
5. Filtering or replacing oil on energized high voltage underground equipment.
6. Operating energized loadbreak components.
7. Immediately following a high-voltage failure.
Reference: APM Rule 316
41
. What steps are taken prior performing work on padmount capacitors?
The following procedures shall be completed prior to performing work on capacitors of any voltage:
1. The capacitors shall be de-energized using the capacitor switches provided.
2. Visually check the capacitor switches open. If any are closed, open manually with live line tools.
3. Check for elimination of current flow with clamp-on ammeter.
4. The source switch position to the capacitor switches shall be opened, locked, and tagged. Using live line tools, the primary terminals to the capacitor installation shall be tested de-energized and grounded.
5. After waiting a minimum of five minutes from de-energizing, the capacitor terminals shall be shorted by means of temporary jumpers and adequately bonded to the case and grounded, using live line tools.
Reference: APM Rule 317.b
42
Which type of fuses are used in a load-break fuse cabinet (LBFC)?
Current-limiting fuses (CLFs).
Reference: DUG, PD 442.1.2
43
Explain APM Rule 307, "Moving Underground Cable."
a. All in-service cables that are to be moved shall be carefully inspected before and after moving.
b. Cables energized in excess of 600 volts shall be moved only under the direction of the supervisor or employee in charge.
Reference: APM Rule 307
44
Upon entering an underground structure, an employee observes evidence of structural compromise, and flexing concrete. According to the DOM, what actions shall the employee take?
5.2 Required response to conditions listed in subsection 5.1
A. Employees will inform their immediate supervisor.
B. Employees will mitigate the hazard to the extent possible, which may include installing remote switching or other isolation methods.
C. The supervisor in charge will notify the Switching Center of the condition and that a temporary "CAUTION DO NOT ENTER WHILE EQUIPMENT IS ENERGIZED" sign was posted, and will prepare a circuit map revision noting the structure is "Closed When Energized."
Reference: DOM, IM-5 5.2
45
. According to the APM, when may underground cable be considered de-energized?
47. According to the APM, when may underground cable be considered de-energized?
Cable and equipment shall be considered energized and worked with adequate protective devices until it has been tested de-energized with an approved device for indication of voltage and grounded with approved ground devices.
Reference: APM Rule 306.b
46
How must the photocells/photoelectric controller for streetlights be oriented when installed?
Photoelectric controller must be installed so photocell is exposed to the north sky.
Reference: DOH, Figure SL 225 Note 1
47
What is the distance a secondary rack is required to be above a phone cable?
Unguarded cables, messengers or racks attached to pole: 6 feet
1. May be reduced to 4 feet with installation of guard arm above communication cables attached to surface of the pole
Reference: DOH, Figure DC 321-1
48
What is the typical function for a RO transformer, in SCE distribution?
This transformer is used to supply series streetlight circuits at a continuous 6.6 amps.
Reference: APM Rule 165.a
49
How are the dielectric values of synthetic or manila rope affected when wetted?
The dielectric values of synthetic and manila rope are similar; dry, they can be considered nonconductors, but when wet, they must be considered conductors.
Reference: RSM, Synthetic Rope C. care
50
When the condition of a synthetic rope that will be attached to an energized conductor is in doubt, what precautions should be taken?
When a rope is to be attached to an energized conductor and there is some doubt about it being wet or dry, an approved insulator (link stick, DE insulator, guy breaker, and so forth) should be used.
Reference: RSM, Synthetic Rope C care
51
For what type of street lighting system are constant-current (regulated output (RO)) transformers used.
Series streetlight circuits are supplied by constant current or Regulated Output (RO)transformers which deliver a constant current of 6.6 A.
Reference: DOH, Glossary
52
What equipment is needed to load check an RO transformer?
2 Potential Transformers (PT) 2400/120 V
One Ammeter
1 Voltmeter
Reference: DOM, TR-5 Attachment 5-1
53
Explain the precautions taken when stringing wire from above or below unattached energized lines or on poles or towers on which there are attached energized lines of over 600 volts.
When stringing or taking down wires from above or below unattached energized lines or on poles or towers on which there are attached energized lines of over 600 volts, precautions shall be taken to adequately insulate the employees from the wire or wire stringing equipment by the use of rubber protective equipment or other approved methods. Employees shall not contact wire stringing equipment in a manner which would permit their bodies to become a parallel path to ground. When conductors being pulled in or out are to be handled by employees on poles or towers, Rule 141 shall apply.
In addition to the above requirements, bare wires (except bare neutrals in multi-conductor cables) shall be pulled over grounded rollers at the first pole or second pole from the payout and takeup equipment and through traveling grounds between the first pole and the payout and takeup equipment. The metal frame of the wire stringing equipment shall be bonded to the traveling ground.
Reference: APM Rule 214.c
53
What must be done prior to closing the secondary leads on a 120/240 V 3% 4-wire delta overhead transformer bank?
Before closing secondary delta leads, verify that the voltage across is less than 20 V. This connection between the leads must be made on the secondary rack.
Reference: DOH, Figure GR 120-2 Note 4
54
Is it permissible for transformers with banked secondaries to be installed on either side of a switch? Explain.
No.
Primary lines sectionalizing devices shall not be located between transformers with banked secondaries.
Reference: APM Rule 217.b
54
What is the minimum distance from the top of the pole to the first through-bolt hole on a new 40-foot pole?
6 ½ inches
Reference: DOH, PO 100.3.2.1
55
May PMHs or PMEs be used to de-energize capacitor banks? Explain.
PMH and PME switches cannot be used for capacitor switching. A sign reading "Capacitor Bank No. Source-Open Capacitor Bank Switch Before Opening This Switch" shall be placed on the compartment door of all PMH/PME switches used to feed capacitor banks.
Reference: DOM, SW-6 2.1
56
Which sizes of conductors are used for single-phase lighting secondaries?
Certain sizes of conductors are most commonly used for lighting secondaries: 1/0 aluminum or #2 copper in all residential areas except those designed for minimum service, and 4/0 aluminum or 2/0 copper where the initial installation requires transformers larger than 25 kVA.
Reference: DOH. DC 400 1.0
57
Which type and size of fuse is used to test a 100 kVA, 12 kV transformer with SMD-20 fuse holders? Is this fuse current limiting?
10 A X-limiter.
Yes, it is current limiting.
Reference: DOM, TS-5 Table 1
58
How does impedance affect the voltage of a transformer?
The voltage drop in an AC circuit is the product of the current and the impedance (Z) of
the circuit.
Reference: 4't Step AC Theory Review Training Manual
59
63. What is the difference between a straddle tap and a standard tap?
Straddle:
5% up and 5% down
Standard:
10% down
Reference: 4th Step Voltage Problems Training Manual
60
Describe the symptoms of shock
1. The shock victim's behavior may range from a feeling of restlessness or agitation to stupor and unconsciousness.
2. The pulse rate will be weak or almost imperceptible; it may retain either a regular or irregular rhythm.
3.Other physical symptoms may be:
a. The face may be pale or ashen.
b. The skin may feel cool and clammy with increased perspiration.
c.Pupils may be dilated or unequal in size and will lack luster.
d. Dizziness, nausea and vomiting may occur.
e.Unconsciousness may develop.
f.Breathing may be shallow or stop.
g.The heart may stop beating.
Reference: APM Rule 1003.b
61
In order to sag conductors properly, how is the appropriate sag chart determined?
In order to choose the sag table most suitable for the particular job at hand, determine the loading district (light or heavy loading) of the line location, the conductor to be used, and the pulling span of the line. Usually the elevation of the service center area traversed by the line, hence the kind of loading (light or heavy) conductor size and kind are known.
Reference: DOH, CO 120.1
61
How often should the neutral of a 12 kV, 4-wire circuit be grounded?
The neutral conductor of all four-wire primary circuits (except isolated neutral systems) shall be grounded (#6 BC minimum) at intervals of approximately 1,200 feet. This spacing applies to the entire circuit, including the feeder and all tap lines. Each tap line, two spans or longer on 4 kV, shall be grounded at its outer ends. Refer to DOH, Section GR, for specific construction practices
Reference: DDS-10, 5.5 A
62
Describe the operation of an RkVAh meter, based on different power factor loads.
For a lagging power factor load, the RkVAh meter will run forward if the phase rotation is correct and will try to run backward (backward rotation is prevented by a ratchet or detent on the disk shaft) if the phase rotation is incorrect.
Reference: DOH, T70.1
63
68. How are SCE and factory-installed test blocks wired?
SCE-installed test blocks are connected in a line-line-line, load-load-load wiring sequence.
Factory (or contractor) installed test blocks are connected in a line-load, line-load, line-load wiring sequence.
Reference: DOH, T34 1.0 and 2.0
64
As it applies to a current transformer (CT) used in metering, how is a CT's overload capability determined?
Overload capability is the ampere rating multiplied by the rating factor.
65
. Describe how and when to shunt CT secondaries.
Before working on instruments or other devices in a current transformer secondary circuit, the instruments or devices shall be short-circuited by jumpers or approved test switches, so that the current transformer secondary circuit cannot be opened while working on the instruments or devices connected thereto.
Reference: APM Rule 136
66
Is it permissible to go inside an area barricaded with yellow tape?
When suitable barrier tape is used to surround or isolate high voltage electrical equipment, an employee shall not be permitted to cross over or under the tape while it is barricading an area, except in an emergency or when work in progress requires the employee to enter the hazardous area. While in the area, the employee shall be continuously watched by another qualified employee.
66
What is the continuous current rating and interrupting rating of the G&W Viper Automatic Recloser?
The G& W Viper-S AR has a continuous current rating of 600 amps and an interrupting rating of 12.5 KA symmetrical.
Reference: DAP, AP 505.1
67
What do the following colors of barrier tape indicate
a. Orange
b. Red
C.Yellow
d. Blue
e. Purple
Red: Danger or Stop
Orange: Identification of hazardous parts or machines
Yellow: Caution
Blue: Safety Information
Purple: Radiation Hazards
Reference: APM Rule 128
67
In an emergency, is it possible to modify or suspend APM rules? Explain.
In case of an emergency which may result in a serious personal injury, a supervisor, or employee in charge, may temporarily modify or suspend any of these rules as may be considered necessary to permit proper handling of the specific emergency. In any such case, the person so acting shall be fully accountable for the reasonableness of these actions and for any accident or service interruption resulting therefrom.
Reference: APM Rule P-6
68
If an employee is insulated from ground and other conductors while working on Edison communication open-wires, must rubber gloves be worn? Explain.
Rubber gloves must be worn when working on all Edison communication open wire lines or equipment unless the employee is adequately insulated from the ground and other conductors, or positively knows the line to be shorted and grounded.
Reference: APM Rule 137.a
69
If it is necessary to climb through a pole-mounted capacitor installation, what actions must be taken beforehand?
B. Before climbing into or through the area of a capacitor installation, automatically switched capacitors shall be de-energized and the controls made inoperative.
C. Contact shall not be made with pole top apparatus as specified in Rule 205 or other metal hardware in the area of an energized capacitor installation.
Reference: APM Rule 215.b
70
Explain the APM Rule 309, as it applies to RAC switches.
If switching on a "RAC" type switch, a blocking device or special handle must be used to ensure that the switch is operated only to the desired position.
Reference: APM Rule 309
71
What is the standard spacing for conductors, on a wood arm, for 12 or 16 kV 4- wire circuits? Also, what is the spacing between the neutral and inside phase?
Phase-to-Phase = 3 feet
Phase-to-Neutral = 40 inches minimum
36"-40"-36"
Reference: DOH, Figure DC 510-1
72
APM Rule 209 addresses working safely in an elevated position. List and explain at least five of these rules
A. Before climbing poles or structures, employees shall familiarize themselves with the circuits, voltages, apparatus thereon, and any unusual conditions which might present a hazard.
B. Not more than one employee shall ascend or descend a pole at the same time. The first employee shall be in place on the pole or on the ground before the next employee climbs or descends the pole. When it becomes necessary for one employee to work above the other, extreme care shall be exercised.
C.Before climbing poles, ladders, scaffolds, or other elevated structures, or riding span wires, messengers, or cables, or entering cable cars, boatswain chairs, or the like, employees shall first assure themselves that said structure or device is strong enough to safely sustain their weight.
D. Before allowing employees to work on any pole from which supporting wires or guys are to be removed, or on which in any way the stress is to be changed, the employee in charge shall make sure that the pole will stand the change in stress without falling. If it is necessary to test the pole, see Rule 202. When the condition of the pole to be worked on is in doubt or when it is not practicable to test, the pole shall be supported before work is started.
E. Employees shall observe height nail or pole brand to make certain that the pole is set to proper depth. (Manufacturers usually place their pole brand 10 feet from the butt end of the pole on 25-foot to 60-foot poles and 13 feet from the butt on all poles 65 feet or longer.)
F. Employees shall not transfer from aerial buckets or baskets to a pole or structure Transfer from an open platform to poles or structures are permitted.
G.Climbers shall not be worn while performing work from an aerial lift.
H. Neither the bucket nor boom shall be allowed to contact unprotected energized conductors. This does not preclude the use of attachments to the boom specifically designed to support energized conductors.
I. When using power tools, grounded material or equipment such as wire, cable, personal grounds, electric cords, etc., approved for use on erected poles, towers, or structures, the tools and all electric supply lines connected thereto shall be kept a safe distance under the level of circuit or apparatus energized in excess of 600 volts or shall be adequately guarded or secured in such a way as to prevent their contacting energized conductors
J. Only approved portable power saws shall be used from elevated positions on erected poles
Reference: APM Rule 209
73
Explain the APM rule concerning overhead bonding.
In addition to bond wires, the term bond, as used in this rule, refers to metal crossarms, metal insulator pins, space bolts, or any other hardware which is attached to insulators supporting energized conductors.
A. Prior to contacting the bonds of energized circuits, the bond shall be grounded or worked with live line tools. Only live line tools shall be used on the bonds of circuits above 20 kV where the conductors are supported on pin or post type insulators.
EXCEPTIONS:
1. Rubber gloves may be used on the bonds of circuits 20 kV or less, only when the integrity of the insulators have been inspected and found to be in good condition.
2. Circuits above 20 kV, where the circuit consists of all suspension type insulators, rubber gloves may be used on the bonds, only when the integrity of the insulatorshave been inspected and found to be in good condition.
B. Every insulator on the circuit shall be checked visually for breaks and cracks on the pole being worked on before contact is made with, or work is done on, the bonds of energized circuits.
1. If a pin or post type insulator is faulty or more than 30% of the insulators in a string of suspension insulators are faulty, the conductor must be cleared, or de-energized before any work is done on the bond.
2. If conditions are such that it is impracticable to clear or de-energize the conductors, the bond shall be worked with live line tools.
C. The following procedures shall be followed if the visual inspection indicates faulty insulators:
1. If any insulator is suspected to be faulty on circuits supported on single unit insulators, the conductor must be cleared before any work is done on the bond.
2.When circuits are supported on multiple unit insulators, at least 70% of the insulators in each string must be in good condition or the conductor must be cleared before any work is done on the bond.
D.Prior to installing or removing a bonded crossarm within minimum approach distance (MAD) of an energizedline the bond shall be removed from insulator pins and/or bolts
Reference: APM Rule 203
74
Briefly explain PM Rule 147, Working Distance. What are the approach distances for 4 kV, 12 kV, and 16 kV circuits? May those distances be reduced?
No employee shall approach or take any conductive object, except with approved devices, closer to unprotected energized parts than shown in the following table:
Approach distances may be reduced, provided adequate approved protective devices are used. Such protection shall be applied and removed with approved insulating devices.
Contact shall not be made with protective devices on conductors energized above 7,500 volts except with live line tools.
EXCEPTION: Employees certified in rubber gloving of conductors energized between 7,500 volts to 17 kV may contact protective devices up to 17 kV while wearing rubber gloves rated for the voltage and while utilizing "insulate and isolate" work practices.
Reference: APM Rule 147
75
What are the number of service drops allowed at one point of service, and what are the exceptions for 120- or 240-volt services?
Not more than one set of service drops will be installed by the Company to any one point-of-service delivery for any single- or multiple-occupancy building for the same voltage and phase classification, except as follows:
120/240 V Single Phase:
Where, for single-phase load only, with service delivery at 120/240 volts, the total load to be served employs sets of service-entrance conductors supplying groups of meter switches, main service switches, or meter switches supplied by individual set at service entrance conductors, with aggregate capacity exceeding the maximum capacity which will be supplied by one set of service drops as specified in Paragraph 2.0 (page 2-5), the contractor shall install two or three separate sets of service-entrance conductors as required thereon for the total load, and provide service terminating facilities for a separate service drop near each service head required.
240 V Single Phase:
For 240 V single-phase power loads, the Company shall be consulted in each case relative to the required serving method. These loads may in some cases be supplied by one 3. phase service drop. In any case, a separate set of service-entrance conductors for connection to a separate service drop may be required by reason of the Company's operating necessity.
Reference: ESR-2, 3.4
76
In general, where are high voltage signs installed on crossarms and poles?
Poles or crossarms shall be marked with approved HIGH VOLTAGE signs. Wherever possible, HIGH VOLTAGE signs shall be placed on the pole at the lowest level of line conductors energized in excess of 750 V, which indicates that all circuits above that level are HIGH VOLTAGE. No additional HIGH VOLTAGE signs are necessary.
As an alternate to marking poles, HIGH VOLTAGE signs shall be placed on all crossarms supporting line conductors energized in excess of 750 V.
3.1.A. Wood Poles — The standard location for marking wood poles with HIGH VOLTAGE signs is on the pole. Use the plastic HIGH VOLTAGE sign (SAP 10135280) with engraved black letters on yellow background and galvanized nails. HIGH VOLTAGE signs are to be placed in order to approximately encircle the pole so that the top of the sign is located no more than 40 inches below the lowest level of the line conductors energized in excess of 750 V.
3.4.A. The standard location for marking poles with HIGH VOLTAGE signs is on the pole. HIGH VOLTAGE signs are to be placed in order to approximately encircle the pole, so that the top of the sign is located no more than 6 inches below the equipment and above supply line conductors energized at 0–750 V and all communication line conductors
Reference: DOH, PO 120 3.0, 3.1.A, 3.4.A
76
Explain the differences between 1 phase vs. 3 phase distribution, as well as the advantages/disadvantages of each.
In a single-phase circuit, power is delivered by only one voltage source that passes through zero every half cycle. In a three-phase circuit, even though one phase may be at zero, there are always two other phases providing power to the system or load. Because of this, the operating characteristics of three-phase apparatus, in general, are superior to those of single-phase apparatus.
Some of the advantages of three-phase circuits over single-phase circuits are listed below:
Generators and motors have about 50% greater output for a given amount of material. Generators, motors, transformers, and transmission equipment are more efficient. Similar distances and losses in power transmission require less conductor material. Motor starting characteristics are more satisfactory, and self-starting.
Reference: 2nd Step Basic AC/DC Electrical Theory Training Manual
77
What is the industry standard for polarity markings on transformers, and how are subtractive and additive polarities indicated?
It is an arbitrary designation, but the standard that has been set up is: Stand facing the low voltage bushing on the transformer. The high side bushing on the left hand side is assigned as the Polarity bushing. This establishes the high side polarity only the low side polarity is established by whether it is an additive or subtractive polarity transformer.
When H1 and X1 are on the same side of the transformer, it is said to be subtractive polarity.
When H1 and X1 are on opposite side of the transformer, it is said to be additive polarity
Reference: 4't Step Polarity Training Manual
78
What is the primary coil voltage of a wye-connected transformer bank installed on a 4 kV circuit?
4 kV = 4,160 V ÷ 1.73 = 2.400 V
Reference: 4' Step Wiring Three-Phase Banks Training Manual
79
Is it permissible to provide a customer with both 3-wire and 4-wire service from the same transformer bank? Why or why not?
No. Do not connect 3-phase, 3 wire services to 3-phase, 4 wire banks.
Reference: DOH, Figure GR 120-2
79
What is the maximum allowable difference in impedance between transformers within a bank?
25%
Reference: 4'" Step Wiring Three-Phase Banks Training Manual
80
All employees must be belted off while climbing wood poles. What are the 3 exceptions?
There are no exceptions.
b. While the use of company-approved wood pole fall restriction equipment is encouraged at all times, employees must use this equipment when ascending, descending and working in elevated positions, whenever there is a possibility of falling two feet or more.
Reference: APM Rule 212.B
81
Why is grounding performed?
Grounding is required for the protection of the worker when working on de-energized high-voltage lines or equipment. Use of personal grounds will minimize exposure associated with making contact with objects having hazardous difference of electrical potentials. Workers should avoid contact with applied grounds wherever possible to minimize exposure to hazardous conditions.
Reference: Overhead Grounding Manual, 2.1
82
When is grounding required? When is it not required
Grounding is required when working on a circuit that is normally energized above 600 V, unless otherwise performing work with live line or other approved insulated tools.
Grounding is also required during wire stringing when high voltage sources are present.
All conductors shall be considered energized until proven de-energized by testing and grounding.
Grounding is not required when constructing a new line section on wood, composite, or concrete poles where there are no high voltage sources.
Reference: Overhead Grounding Manual, 2.2
83
List the high voltage sources, as defined by the grounding manual
Open Breakers, Open Switches, Open Taps, or Open Fuses
Crossings
Backfeed
Induction
Static Charge
Reference: Overhead Grounding Manual, 2.1.1
84
Which two electrical ratings are used when determining ground size(s)?
Source voltage and fault-current duty at the worksite or source substation(s).
Reference: Overhead Grounding Manual, 3.2
85
What is the minimum height a pole band must be installed on a pole?
12 feet from ground level.
Reference: Overhead Grounding Manual, 3.6.9.7
86
What size grounds would be applied for work on a 16 kV circuit with 9 kA fault duty?
#2 AWG
Reference: Overhead Grounding Manual, 3.2 table 3-1
87
List the overhead grounding schemes in order of preference.
1. Parallel
2. Balanced
3. Unbalanced
Reference: Overhead Grounding Manual, 3.6.12 figure 3-25
88
Where transformers or secondaries are banked - or there is a possibility of backfeed and the primary cutout is open, what precautions must be taken before doing any work on the primary side of the transformer?
Where secondaries of transformers are banked or there is a possibility of a backfeed, the transformer secondary leads shall be disconnected in addition to pulling primary fuses before any work is done on a transformer.
Reference: APM Rule 217.a
88
Under what circumstances would burn victims require medical attention?
a) Burn is larger than the size of the person's open hand
b) Burn contains blisters.
c) Burn darken or breaks the skin.
d) Burn involves the face, hand, foot, genitals, or skin-folds (i.e. flexural areas).
e) Burn is not completely clean.
f) Burn causes pain that is not relieved with over the counter pain medication (e.g. acetaminophen) or does not improve within 24 hours.
g) Burn victim may have inhaled smoke or extreme heat.
h) Burn victim has other major injuries resulting from the cause of the fire.
Reference: APM Rule 1006.b.1
89
. A clip-on ammeter reads 7 A on a 120 V conductor. What is the resistance?
R= E÷l
R= 120 V ÷ 7 A = 17.1 0
Reference: 4th Step Ohm's Law and Power Training Manual
90
How much current would a 240 V heater, with 20 Ohms resistance, draw?
I = E÷R
I = 240V ÷ 20 = 12 A
Reference: 4' Step Ohm's Law and Power Training Manual
91
A 2000-watt electric heating unit is supplied by a 240 V circuit. What is the current drawn by the heater?
I= P ÷E
1 = 2000 W ÷ 240 V = 8.33 A
Reference: 4th Step Ohm's Law and Power Training Manual
92
. If a circuit has a total resistance of 15 Ohm and a current of 3 A, what is the voltage of the circuit?
E= IxR
E = 4 Ax 60 Ohms = 240 V
Reference: 4th Step Ohm's Law and Power Training Manual
93
What is the full load for a 150 kVA 30 transformer bank with 120 V secondaries?
Reference: 4th Step Ohm's Law and Power Training Manual
94
. A 1 phase 120/240 V circuit is tested with a voltmeter and an ammeter with the following results: 240 V and 150 A. At the time of measurement, the service meter measures 24 KW. What is the power factor?
Reference: 4th Step Ohm's Law and Power Training Manual
94
Where, on the SCE system, are voltage regulators typically located?
Generally, voltage regulators are located inside substations. However, "field regulators" exist on longer circuits, usually over 10 miles, where adjusted voltages are needed
Reference: 4th Step Voltage Regulators Training Manual
94
What is the basic application for a voltage regulator on the SCE system?
Voltage regulators are used to adjust the primary voltage, downstream, on their respective circuits. A voltage regulators may be thought of as an automatic transformer which may, upon demand, "boost" or "buck" circuit voltage.
Reference: 4th Step Voltage Regulators Training Manual
95
. Describe the general operation of an electromechanical ground relay.
The electromechanical type of non-directional ground overcurrent relays applied in substation protective schemes use an induction disc similar to a CO or IAC type relay. The induction disc operates by torque derived from the interaction of fluxes produced by an electromagnet with those from induced currents in the plane of a rotating aluminum disc.
Reference: 4th Step Ground Relays Training Manual
96
What are the two types of ground relays used on the SCE system?
The ground relays used on the SCE system are either the electromechanical type, or the newer micro-processor based multi-function intelligent devices (IEDs).
Reference: 4' Step Ground Relays Training Manual
97
What is the general function of ground relays?
Both, directional and non-direction, ground overcurrent relays are used in a wide range of ground protection applications to sense a ground fault condition on lines and equipment at all voltage levels.
Reference: 4th Step Ground Relays Training Manual
98
Explain the basic operation, and voltage range, of a step voltage regulator.
For a step regulator, output voltage will change by 5/8th of one percent of the unregulated voltage for each step. Referenced to 120 volts, this is 0.75 volts per step.
Step regulators are adjustable for a total of 5%, 7-1/2%, or 10% boost or buck. The 10% boost is accomplished in 16 steps above the neutral position. As the polarity of the tapped coil can be changed with a reversing switch to buck the voltage, a 10% regulator will have a total of 33 steps. For 7-1 /2% regulators, there are 25 steps; for 5%, 17
Reference: 4' Step Voltage Regulators Training Manual
99
Explain the basic application and operation of an induction voltage regulator.
A. This is primarily a station regulator.
B. By changing the position of one winding with respect to another winding, you change the voltage. This is because you have changed the magnetic lines of flux to get zero or maximum voltage.
C. It will continually pivot in order to alter its magnetic field and thus the voltage (it is like an A-bank).
D. Principle:
Induction regulators use a magnetic flux principle, somewhat similar to a variable ratio autotransformer. The induced voltage is always in phase with the excitation voltage and is added to or subtracted from the source voltage.
No flux from the primary or exciting winding links the turns of the secondary, or series, windings of the stator.
Reference: 4th Step Voltage Regulators Training Manual
99
Briefly describe the three types of voltage regulator banks.
1. Y-bank - 4 wire
a. The exciting voltage is phase to ground voltage.
2. Delta bank
a. The exciting voltage is phase to phase voltage.
3. Open-delta bank
a. Two regulators are connected to a 3 wire circuit.
b. It is used in rural areas and is rated in kVA
4th Step Self-Study Questions
Reference: 4' Step Voltage Regulators Training Manual
100
How is the use of voltage regulators justified economically?
They increase revenue by increasing the average voltage at the utilization point.
Generally, a two percent increase in average voltage level increases kilowatt hour consumption by one percent. In addition, a good voltage level, consistently delivered, is a consumers measure of service and encourages a trend to all-electric living.
Reference: 4th Step Voltage Regulators Training Manual
101
Describe the grounding requirement for a pole-mounted single-phase voltage regulator.
Ground the voltage regulator tank with one continuous run of #4 PGW. The tank ground shall be brought up to the pole top and terminated to the ground conductor directly beneath the surge arrester cross arm. Terminating the tank ground at this location limits the magnitude of voltage impressed upon the regulator during transient conditions. DO NOT terminate the tank ground to the ground conductor at any other location on the pole.
Reference: 4th Step Voltage Regulators Training Manual
102
What is the approximate maximum weight of a fixed capacitor bank?
Approximate maximum weight of fixed capacitor bank is 540 lbs. This includes rack and capacitor units.
Reference: DAP, Figure AP 210-1 note 8
103
Approximate maximum weight of fixed capacitor bank is 540 lbs. This includes rack and capacitor units.
Reference: DAP, Figure AP 210-1 note 8
150 kVAR and 300 kVAR.
Reference: DAP, Table AP 200-1
104
. Describe the connection schemes for preassembled, switched, capacitor banks installed on 12 kV and 16 kV circuits?
Cap banks for 4.16 kV, 12 kV and 16 kV are Ungrounded-Wye connected and designed with two vacuum switches.
Reference: DAP, Table AP 200-1
105
. After installing a 2.4 kV switched overhead capacitor bank, how will the construction crew leave the capacitor controls?
Capacitor control shall be left energized with 120 VAC, in MANUAL, LOCAL and OPEN mode by construction crew at time of installation. Apparatus will program control settings and commission the unit.
Reference: DAP, Figure AP 221-1 note 12
