Distribution And Incidents Flashcards
Con ed electric customers
~3.5 million
How many customers network/non-network
~2.6 million network
~900,000 non-network
Electric service territory
~604 square miles
Con ed #area substations
62 area substations
What does second contingency mean?
.
Voltage levels
Westchester: 13kV, 4kV Bronx: 13kV, 27kV (Co-Op City), 4kV Queens: 27kV, 4kV Brooklyn: 27kV, 4kV Manhattan: 13kV Staten island: 33kV, 13kV, 4kV
the individual voltage levels are a result of the design choices by the companies that were consolidated to form Con Edison
Manhattan # area substations, networks, daily peak network load, customers
28 area substations (but 2 in bronx) 39 second contingency networks Network peak load summer: ~21MW-275MW ~750,000 customers Peak hours ~8am-4pm (other boroughs have higher in evening)
Two main distribution design Systems
Network ( 80% of the load )
Radial: Auto loop, 4kv unit substation grid, underground residential distribution Systems
Describe a network distribution system
Designed for a second contingency in the city and first contingency in Westchester / Staten Island
Primary feeder -> network transformer/network protector -> secondary 120/208 V grid tied together
Describe Auto loop distribution system
Designed for single contingency, mostly in Staten Island / Westchester
27 kv, 13 kv, 4kv
Either three or five recloser designs
provides enhanced reliability to supply feeders or separated by normally open tie recloser. If one read feeder fails, the fault is isolated by the normally closed feeder / midpoint reclosers and the tie recloser closes to feed from the other supply feeder
Jodie Lane fatality
In 2004, Jody Lane, was walking her two dogs on East 11th Street and made contact with an electrified service box and was electrocuted and died. The cause was a 120 volt shunt cable which was not properly insulated. over the next two months, Con Edison tested all of its electric system underground structures for stray voltage, and also committed over 9 million dollars to fund stray voltage detection programs.
Ukraine Cyber attack
In 2015, the first successful Cyber attack against a utility was coordinated against three utilities in ukraine. They took control of the utility scada Systems and removed critical substations from service, causing an outage for over 200,000 people for several hours. This attack began with fishing
Plymouth Street breaker
In 2017, to $138kv feeders at Plymouth Street substation opened automatically. Hall Network into Ace contingency and interrupted service to many customers including MTA lines.
The fault originated on a feeder and a manhole near the Plymouth Street area substation, but a breaker in the substation was slow to open which led to unnecessary isolation and equipment damage. No injuries but potential for injury if anyone had been near the slow breaker, which was physically ejected from its cubicle.
Con Edison reviewed all similar breakers and ultimately corrected over 100 breakers that were also out of specification. Renewed focus on rigorous procedural adherence
Puerto Rico mutual assistance
In 2017, hurricane Maria cause catastrophic damage to Puerto Rico’s electric infrastructure, resulting in the loss of over 1.5 million customers. Con Edison was the first utility to respond to Puerto Rico that was not working for the army corps of engineers. No ConEd injuries and the New York State contingent (led by Con Edison in New York power authority) was responsible for over 24% of the Puerto Rico restoration
Super storm Sandy
in 2012, superstorm Sandy was the most damaging storm event in company history, left more than 1 million content customers without power.after super storm Sandy Con Edison continued its enhanced focus on storm hardening and flood protection, including making sure that new transformers and network protectors at or below sidewalk level must be submersible or installed above flood level
in 2013 Con Edison submitted a rate proposal with 1 billion dollars in investments to protect customers from devastating storms
Dunwoodie
In 2009 the low tap changer leads of the Dunwoody Auto transformer failed. This caused an explosion and fire. The transformers fire protection was not operable because of damage to the DC supply.
the transformer was located in a concrete mode. An oil water separator separates oil from water that collects in the moat. due to a problem with the oil water separator, about 15,000 gallons of dielectric fluid were released into the environment, some of which was discharged directly into the Bronx River.
Con Edison had to pay a civil penalty of nearly 800,000
Con Edison installed a new transformer and repaired the oil water separator. The committee was also formed to evaluate conditions at substation facilities and consider future upgrades for fire protection and oil/water separation
Floral Park gas event
in 2009, residents reported a partial electric outage and outside gas odor to con edison. GDs mechanics arrived and detected gas readings and subsurface structures and high readings near electric service box. Additional Con Edison Cruise arrived and were in the process of removing the service box to allow the structure to vent when a house across the street exploded into flames. One fatality and several injuries
root cause: arcing underground electric service cable created dime-sized hole in high pressure gas main close by. Outside migration investigation were not suspended to vent nearby enclosed spaces
Operational improvements:
- GERC provides initial information on gas facilities connected to electric facilities for leak response
- Suspend migration investigation and require immediate building entry for gas readings in evacuation when gas readings detected within 5 ft of building or detected in manhole/SSS
- Request fire department and additional company crews - Code MURRE
East Harlem
2014 explosion and resulting collapse destroyed two buildings and park avenue. Eight fatalities and over 50 injuries.
153 million settlement, smell gas act fast, monthly patrols of gas means, Ami natural gas detector pilot program, improved emergency response procedures with fire department, improved leak response and made save times
February 9th 2021 fresh kills / Woodrow
About 14,000 customers impacted, all restored after 12 minutes
fresh kills 33 KV feeder position breaker 41s opened due to pothead fault. the relay protection for that feeder operated correctly. Multiple breakers at fresh kills 138 KV station opened Auto when they should not have, most likely because the auxiliary CTS feeding the differential protection microprocessor relays saturated
Steps taken:
engineering issued test letter, CT saturation tests, correct relay clocks, CT burden tests, circuit modification for inputs to microprocessor relays (remove the aux CTS and compensate by raising the minimum pickup for the differential microprocessor relay)
March 13th, 2021 MTA contractor high voltage arc flash injury
an iron worker was critically injured after she was electrocuted while working on a construction site along the Long Island railroad. trees were putting up a pedestrian bridge over the tracks when a crane came into contact with high voltage wires. this created an arc to the bridge that seriously injured a female iron worker who was on the structure
Westside outage
On July 13th, 2019, approximately 73,000 ConEd customers on the west side of Manhattan lost electric Service. Con Edison recognizes the distress that this caused our customers and quickly mobilized restoration efforts: all customers were back in service within 5 hours.
The outage began with a 13kv distribution feeder experiencing an electric fault near West 65th Street station. The relays at both ends of the feeder operated correctly to isolate the feeder fault. However protective 87n relays on three transformers at West 65th Street station Miss operated, the energizing 6 138 KV feeders. because this overloaded additional transformers, additional networks had to be shut down manually. Six networks total were lost.
the underlying cause was a missing neutral wire between the transformer breaker CT and the neutral auxiliary CT for the 387n relay circuits. This occurred during a 2008-2009 breaker retrofit project, there was an ambiguity between a vendor and ConEd circuit drawings
ConEd isolated 211 87N relay circuits
