1 4-3 industrial cramond & carreras optical acr flash protection

8/9/2019 1 4-3 Industrial Cramond & Carreras Optical Acr Flash Protection

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Optical Arc Flash Protection: Real World Experience

Authors:

James Cramond P.E., Yale University

Angel Carreras, ABB Inc.

Texas A&M University65th Annual Conference for Protective Relay Engineers


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One line diagram of the Yale’s existing electrical system


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Arc flash relays


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Yale University Optical Arc Flash fiber optic runs and relaylayout


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Arc Flash System

•Three master units and one extension unit were used for each bus.

•Each master unit has one fiber optic sensor port, a three Phase

current input and 2 high speed output that will send a trip signal

within 2.5 ms when both a current and light signal are detected

simultaneously.

•The extension unit has one fiber optic sensor port, 2 high speed

output and one RJ45 input and one RJ45 output ports that are used

to connect to the master unit.

•The three fiber optic sensors, one from each master unit, were

routed through the breaker, bus and cable compartments of the

switchgear. The extension unit’s fiber optic sensor was routed

through the tie breaker compartment.


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Arc Flash System Cont.

•Each master unit monitored the three phase currents from one

of the incoming source; and its high speed output contact was

wired to the incoming source breaker. The extension unit’s

high speed output contact was wired to the tie breaker.

•When the arc flash occurred in cubicle 19 the overcurrent and

light signals were activated and the master and extension units

open their prospective breaker thereby isolating andextinguishing the arc flash immediately (2.5 ms + 3 cycle

breaker speed approx. 48 ms) resulting in minimal damage to

the switchgear and no injuries to personnel.


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Main-tie-main lay-out with event as bolt

13.8 kV Bus A 13.8 kV Bus B

13.8 kV Bus C 13.8 kV Bus D

1536 1527

2221

1525

1 2

1528

U.I. U.I.

11

Tie

GT-1 GT-2

19


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Yale Medical Campus Power Outage

First Fault occurred on August 9, 2010

30 cycle UI Fault

Contributed to Bus Bar insulation degradation

Second Fault occurred on August 16, 2010

UI Fault during a Line splice

Concluded with Arc Flash between Bus Bar and CT

shielded cable.


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Sequence of Events on August 16, 2010

At 10:42 am on 8/16/10 UI feeder breakers 1527(position22) and1536(position 21) on SPP 13.8K B-Bus as well as both GT

Breakers tripped, causing a campus wide power outage.

SPP was in low load configuration at the time of the fault, with

B-Bus UI feeders in service and the Tie breaker closed.

Representatives from Engineering, High Voltage Maintenance,

Physical Plant personnel were immediately dispatched to SSP.

Upon examination, instrumentation indicated a very large

electrical fault but not in the Yale Substation.


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Sequence of Events on August 16, 2010 Cont…

Yale called UI Dispatch to see if an event had occurred on their

system. According to UI a feeder fault had occurred on feeder

1529, which is a feeder serving another customer out on the Water

St. Substation and is the same bus as feeder 1527 and 1536. It was noted by UI that a contractor working on a line splice

caused the fault. At this time UI had not cleared the fault and Yale

requested that UI notify us when fault was cleared.


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Sequence of Events on August 16, 2010 Cont…

Based on the information provided to us by UI on what cause the

event, the “A-B” Bus Tie breaker was opened and then the A-Bus UIfeeder(numbers 1525(position 1) and 1528(position 2)) were closed

in and placed into service around 11 AM, Thus restoring partial

power to some to the campus buildings(those that were fed from the

A-Bus at the time.

Our HV group was immediately dispatched to begin transferring all

campus buildings from B-Bus to A-Bus to restore power.

All building emergency generators were started and remained

operational through the day. They were turned off one by one until

the last one was turned off line at 3 PM.


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Sequence of Events on August 16, 2010 Cont..

At approximately 11 AM Yale received a call from UI stating that

they had isolated feeder 1527 and 1536. During the entire eventfeeders 1527 1nd 1536 (those serving B-Bus) remained live and did

not trip at the Water St. substation.

At around 11:30 AM Yale reset the lockout and protection relays on

the two UI feeder breakers(1527 &1536) along with the two GT

breakers. With breakers reset, an attempt was made to close in on

the tie breaker to fully restore the campus.

When the tie was closed an arc flash was immediately detected by

the newly installed arc flash system which opened the Tie breaker

and did not allow the arc flash to evolve into a catastrophic event.

(Bus Differential protection never detected the fault due to fast

response of the Arc Flash protection system.)


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Sequence of Events on August 16, 2010 Cont..

In conclusion, it appears that the utility fault caused the

Yale system to back feed significant current on two phases

which compromised components within our switchgearand generators. When Yale attempted to close the13.8 kV

“A” and “B” bus tie breaker, the compromised components

failed causing an arc and subsequent damage to sections of

the switchgear and internal devices.


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Recorded event of the first fault caused by utility thatinitiated the events on 8/16/2011


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Graph of the actual Arc Flash event


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Yale Sterling Substation ARC Flash

Arc flash occurred in Cubicle 19 of the B-Bus

Detected by Master units-1B,2B,3B and a trip signal was

sent from Master unit to extension unit via RJ45 extension

cable to open Tie Breaker. Fault clearing time(breaker open) – approximately 50.5ms

Current and light detection time was < 2.5ms

Breaker speed was 3 Cycles- approximately 48ms


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Results of the Arc Flash system installation

No personnel were injured.

More than 6 Yale and UI personnel were within close proximity

of the Sterling Switchgear when the Arc flash Occurred.

Minimal damage to switchgear and equipment

Bus section, CT shielded cable, 2 CT and fiberglass barrier

replaced

Minimal down time – < 12 hours

Section of Bus was fabricated and installed, new CTs andshielded cables installed, and fiberglass barriers fabricated;

switchgear commissioned and put back in service with 12

hours.


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Sterling Switchgear Cubicle 19 Arc Flash Damage


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Benefits to Using Light and Current Arc Flash MitigationSystem

Fastest Arc Flash detection system.

Can mitigate Level 4 PPE down to Level 2 & 1

Detects Arc (light) and Overcurrent and initiates trip to breaker

in less than 2.5 ms.

Can be retrofitted easily into existing switchgear

Is secure, and reliable.

Will trip only if an over current and light are detected

simultaneously

Has internal diagnostics and alarming to detect fiber loop

failure, optolink fiber failure or RJ45 extension cable failure.


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Benefits to Using ABB REA Arc Flash Mitigation System Cont.

Provides Arc Flash Protection 24/7- Always On

High ROI


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In Summary

Highly recommend the current and light sensing arc flashprotection system for arc flash mitigation.

Yale personnel including myself who were in close proximity of

the Sterling switchgear during the arc flash incident were not

injured as a direct result of the arc flash protection systembeing installed.

Yale Switchgear equipment sustained minimal damage and

down time.

Yale has installed the same Arc Flash protection system in its

Sterling and the Central substation’s 13.8 KV switchgear.

1 4-3 industrial cramond & carreras optical acr flash protection

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