Improving Power Quality on Tideland’s Merritt Circuit
Improving Power Quality on Tideland’s Merritt Circuit
This spring, Tideland EMC began several construction projects to improve service reliability and increase capacity on the Merritt circuit. Unfortunately, co-op members in that area have also experienced power quality issues in recent weeks, including two outages within the past 10 days. Here is an overview of the work taking place to improve long-term performance of the Merritt circuit. We also detail the circumstances surrounding the June 10th and June 19th outages.
ABOUT THE MERRIT CIRCUIT
• Total of 99 miles of overhead line (three-phase, primary, tap and service wire)
• 45 miles of three-phase line
• It is the longest circuit in Tideland’s 6-county service territory
• Provides service to 1,852 members in Pamlico County
• $1.6 million is being invested to make Merritt circuit improvements
WORK UNDERWAY:
Redirect the Merritt circuit exit from Silver Hill substation
INVESTMENT: $500,000
This will effectively reduce the circuit’s length 1 mile. Because this is new construction and crews are not working on energized structures it does not impact power quality.
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WORK UNDERWAY:
Right-of-Way Maintenance & Tree Trimming
INVESTMENT: 305,000
Right-of-way crews began work on the Merritt circuit earlier this month. They are working their way along the Florence feeder (Highway 304 corridor) towards Trent Road. Their work includes tree trimming along all side roads as well. When they complete that section they will continue to make their way south until they reach Teach’s Cove. Depending on weather, right-of-way crews will likely be a daily presence through the end of September.
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ONE-SHOT BREAKER OPERATIONS:
BLINK VS OUTAGE
- A fault has been detected. (examples: limb on line, animal contact, foreign object, broken insulator)
- System breaker or recloser operates to allow electricity to momentarily stop flowing to allow the fault an opportunity to clear. This is a blink.
- Power resumes. If a fault is still detected the process is repeated a second time. Another blink.
- Power resumes. If a fault is still detected the process is repeated a third time. Another blink.
- Power resumes. If a fault is still detected the breaker or recloser now locks out, an outage occurs and Tideland crews are dispatched.
Without properly operating breakers and reclosers, Tideland’s utility wires, poles and equipment could sustain a great deal of damage resulting from fires and hazardous voltage conditions. Electricity can have the effect of holding a foreign object in place which allows it to burn. By momentarily interrupting the flow of electricity that object has an opportunity to break free from utility structures.
One-Shot Setting
When crews work on energized lines safety is our top priority. Therefore, we place the breaker in one-shot mode while they are working. That means should anything come in contact with the line and a fault is detected, the breaker automatically locks out and we have an outage. The intent is to protect personnel. On Monday, June 10, the entire Merritt circuit lost power at 9:30 am, when a bird came in contact with energized structures. Normally the contact would have resulted in a blink and power would have likely remained on after the bird cleared the structure. Because the breaker was on one-shot to protect line crews, the bird contact resulted in an actual outage. Power was restored 35 minutes later. On the evening of June 19, 1,607 members on Merritt Circuit lost power following a lightning strike. While the strike did not damage co-op equipment, the breaker was set on one-shot while construction crews worked. The outage lasted 51 minutes.
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WORK COMPLETED:
Bay River Cable Crossing
INVESTMENT: $600,000
The co-op installed 2,080 feet of submerged cable at the Bay River to eliminate that section of overhead line.
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FUTURE PROJECT:
Reconductor Merritt Circuit Three-Phase along Trent Road
INVESTMENT: $422,000
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FUTURE PROJECT:
New Tie-Line between Merritt and Dawson Creek circuits
INVESTMENT: $289,000
The new tie-line will travel from Kershaw Rd to Orchard Creek Rd.
