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Substation Safety and Equipment
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Substation Safety and Equipment
Substation Safety and Equipment
Study
1
Question
Please list the Six (6) major categories of discussion for any Tailboard:
Page 1
Answer
Methods of emergency notification; the job plan; job hazards; what is energized and what is not, including clearance points; assignments, groups, or individuals; special precautions, special equipment, and PPE; and questions from participants.
2
Question
What is the proper procedure for tagging open disconnect switches?
Page 1
Answer
Inspect the disconnect. Contact PDO to receive a clearance on it. Complete a “Do not operate” tag with the clearance number, name, date, and contact information. Attach the tag to the disconnect while it is open and locked.
3
Question
What can result from removing another person’s tag and operating the switch without proper authority?
Page 1
Answer
It could cause injury or death to personnel, damage property, and result in termination.
4
Question
What safe working distances are listed for qualified and unqualified personnel in 230 kV and 500 kV yards?
Page 2
Answer
230 kV: unqualified, 13’0”; qualified, P-G 5’8” and P-P 8’5”. 500 kV: unqualified, 18’0”; qualified, 20’4”.
5
Question
Which basic safe work practices apply in 230 kV or 500 kV receiving stations?
Page 2
Answer
Check in by phone or sub-entry software; keep unmonitored gates closed and locked; follow posted traffic signs; observe overhead clearances to energized conductors and qualified and unqualified MADs; use PPE; and inform personnel of your presence and tailboard with the crew.
6
Question
What clearance distance above ground is listed for personnel safety at 12 kV?
Page 2
Answer
9’0”.
7
Question
What clearance distance above ground is listed for personnel safety at 69 kV?
Page 2
Answer
10’5”.
8
Question
What clearance distance above ground is listed for personnel safety at 230 kV?
Page 2
Answer
13’9”.
9
Question
What clearance distance above ground is listed for personnel safety at 500 kV?
Page 2
Answer
20’6”.
10
Question
At what elevation do minimum approach distances change, and how do they change above it?
Page 3
Answer
Above 3,000 feet above sea level, MADs increase by a correction factor found in Appendix A of the APR.
11
Question
What voltage range classifies an electrical circuit as secondary?
Page 3
Answer
A circuit that normally operates at less than 600 volts is classified as secondary.
12
Question
What voltage range classifies an electrical circuit as primary?
Page 3
Answer
A circuit that normally operates at 600 volts or more is classified as primary.
13
Question
Why must potential transformers be isolated before work on a 12 kV switchgear bus?
Page 3
Answer
To eliminate the possibility of back-feed. Primary conductors and equipment, including PTs and CPTs, are considered energized until isolated from all primary and secondary voltage sources, tested for voltage, and grounded in accordance with PPG Standards.
14
Question
Which precautions apply when employees install or maintain batteries?
Page 3
Answer
Only qualified employees may install or maintain batteries and associated equipment. Smoking, open flames, and other combustion ignition sources are prohibited near batteries.
15
Question
Which protective measures are required when handling acids or damaged batteries?
Page 4
Answer
Wear a rubber apron, face shield, and appropriate hand and eye protection. Ensure eyewash provisions are available near the work area.
16
Question
What is an indeterminate under substation clearance standards, and which examples are given?
Page 4
Answer
It is non-conductive, ungrounded material or apparatus that could have voltage on it. Examples include an insulator, the outside of a bushing, and ungrounded metal parts.
17
Question
Who can release a clearance?
Page 4
Answer
The clearance holder or an immediate supervisor.
18
Question
How far must a ladder extend above its supporting structure?
Page 4
Answer
A minimum of 3 feet.
19
Question
What does back-feed mean in an electrical circuit?
Page 4
Answer
The intentional or unintentional energization of a circuit outside its normal source. Generators providing temporary power are an example.
20
Question
Which precautions must be completed before entering a manhole?
Page 5
Answer
Conduct and complete a pre-entry tailboard; complete the enclosed-space entry checklist to determine whether a confined-space permit is required; test for a hazardous atmosphere; ventilate the space; set up rescue equipment; ensure 100% tethering; barricade the area; and assign an outside attendant to maintain contact.
21
Question
What steps are required before entering an energized vault?
Page 5
Answer
De-energize it if possible; if not, obtain management approval. DOC/TGO must complete the Enclosed Space Emergency Switching Form. Have the test group perform IR imaging for hot spots; IR-scan and blanket any splices; have a qualified person ready to rack out the breaker if needed to isolate the space; and obtain a hold tag for circuits inside the vault.
22
Question
Who may work in an energized vault under the stated requirements?
Page 5
Answer
An electrically qualified person may work in an energized vault. The listed staffing condition is 2 journeymen and/or a hot apprentice under a journeyman’s direct supervision.
23
Question
What minimum crew size is specified for work in an energized vault?
Page 5
Answer
Three or more, based on the job scope.
24
Question
What does Blue Stake Service do, and when must it be completed?
Page 5
Answer
It determines the location of and marks underground utilities in the work area. It must be completed before excavation outside a substation.
25
Question
How much time does Blue Stake Service require to perform its function?
Page 6
Answer
Two full workdays.
26
Question
What is a hold tag used to indicate?
Page 6
Answer
It is an approved tag or card warning against operation of a particular switch, device, circuit, tool, machine, gate, or other equipment. It may also indicate disabling a breaker or recloser’s reclosing operation.
27
Question
What characterizes a diminished hold tag on a ground relay?
Page 6
Answer
The timing (51G), rather than instantaneous (50G), portion of the ground relay has been disabled. This raises the tripping current level and the safety threshold.
28
Question
What happens when the re-closure toggle switch is moved to the off position?
Page 6
Answer
It prevents a breaker from automatically closing.
29
Question
At what trench depth is cave-in protection required for an employee’s entry?
Page 6
Answer
At least 5 feet deep.
30
Question
What does M.O.D. stand for in substation equipment terminology?
Page 6
Answer
Motor operated disconnect.