PECO Distribution Systems & Infrastructure 1 — Questions and Answers
Question 1: What is the standard secondary distribution voltage delivered to most residential customers in PECO's service territory?
- 120/240V single-phase (Correct answer)
- 208/120V three-phase
- 480/277V three-phase
- 13.2 kV
Correct answer: 120/240V single-phase
Residential customers in PECO's territory receive 120/240V single-phase service from the distribution transformer secondary.
Question 2: Which component steps down primary distribution voltage to utilization voltage for end users in a PECO distribution circuit?
- Capacitor bank
- Distribution transformer (Correct answer)
- Recloser
- Sectionalizer
Correct answer: Distribution transformer
Distribution transformers step down the primary distribution voltage (e.g., 13.2 kV or 4.16 kV) to secondary utilization voltage (120/240V).
Question 3: PECO's primary distribution system most commonly operates at which voltage level for underground residential distribution?
- 4.16 kV
- 13.2 kV (Correct answer)
- 69 kV
- 138 kV
Correct answer: 13.2 kV
PECO's underground residential distribution (URD) circuits typically operate at 13.2 kV primary voltage in most of its service area.
Question 4: What is the primary purpose of a distribution substation in the PECO grid?
- Generate electricity from renewable sources
- Step down transmission voltage to primary distribution voltage (Correct answer)
- Store excess power during off-peak hours
- Measure customer consumption for billing
Correct answer: Step down transmission voltage to primary distribution voltage
Distribution substations use power transformers to step down high transmission voltages (e.g., 69 kV or 138 kV) to primary distribution voltage levels for local feeders.
Question 5: Which switching device on a PECO overhead distribution feeder automatically interrupts fault current and attempts to restore service through pre-programmed reclosing sequences?
- Fuse cutout
- Recloser (Correct answer)
- Sectionalizer
- Disconnect switch
Correct answer: Recloser
A recloser automatically opens on a fault and then attempts to reclose a set number of times to restore service for temporary faults before locking out.
Question 6: In PECO's distribution infrastructure, what does the term 'feeder' refer to?
- A high-voltage transmission line connecting substations
- A medium-voltage circuit originating from a substation bus that supplies distribution transformers (Correct answer)
- An underground cable connecting a meter to a panel
- A conductor connecting a customer transformer to the service entrance
Correct answer: A medium-voltage circuit originating from a substation bus that supplies distribution transformers
A feeder is a medium-voltage circuit (primary distribution) that originates at a substation bus and supplies multiple distribution transformers along its route.
Question 7: What is the role of a sectionalizer in PECO's distribution system?
- Continuously regulate voltage along a feeder
- Count fault current operations and open after a set number to isolate a faulted section (Correct answer)
- Provide reactive power compensation
- Automatically reroute power during outages using SCADA
Correct answer: Count fault current operations and open after a set number to isolate a faulted section
A sectionalizer counts the number of times fault current passes through it and opens after the upstream recloser locks out, isolating only the faulted section of the feeder.
PECO Distribution Systems & Infrastructure 1
What is the standard secondary distribution voltage delivered to most residential customers in PECO's service territory?