WWCC Arc Flash Mitigation Atlanta

Smart Water for

Smart Cities

Arc Flash Mitigation

Enhancing Personnel Safety

Terry L. Schiazza

Low Voltage Offer Marketing

Seneca (SC) Plant

Sponsored by the Water Wastewater Competency Center

Atlanta, GA May 2014

2

Graduated (1980) Georgia Institute of Technology Bachelor of Mechanical Engineering

Graduated (1991) Clemson University

Master of Human Resource Development

Began career at Square D in 1980 and serve as Business Development Manager for Partner Business Unit

Member of IEEE/IAS and AIST - IEEE/PCIC Chemical Subcommittee

- AIST Energy Applications Technology Committee

Standards Working Group member of - IEEE 1683

- IEEE C37.20.7

Terry L. Schiazza

Co-authored published IEEE paper (Paper No. PCIC-2008-31) presented at the 2008

Petroleum and Chemical Industry Committee

(PCIC) conference in Cincinnati.

ELECTRONIC MOTOR CIRCUIT PROTECTORS

A fresh perspective on sizing circuit protection for

branch motor circuits in a low voltage motor

control center

Co-authored published AISTech 2012 Proceedings (Paper 25222113) presented at the 2012 Association

for Iron & Steel Technology Conference in Atlanta.

New Approach for Intelligent Motor Control Centers

*Recipient of the 2013 AIST Farrington Award received

at the Pittsburgh Technology Conference

Arc Flash Principles and Theory

Arc Flash Characteristics Arc Blast & Arc Flash occur

together. The term Arc Flash

often refers to both

phenomena. From here on,

the term Arc Flash will be

used for both terms.

Thermal

Effects

Pressure

Effects

Why is Arc-Flash Analysis Important?

Need to provide optimal safety for electrical workers

Increasing awareness of arc-flash hazards

Calculation of Arc-Flash Incident Energy (AFIE) allows selection of adequate Personal Protective Equipment (PPE) if equipment must be worked while energized

Working on or near exposed live parts: NFPA 70E requires an arc-flash hazard analysis if equipment >50V is not placed in an electrically safe working condition

OSHA is enforcing NFPA 70E!

NEC 2014 Impact Changes (Section 240.87)

NFPA 70E PPE Table Table 130.7(C)(11) Protective Clothing Characteristics

Typical Protective Clothing Systems

Hazard/Risk

Category

Clothing Description

(Typical number of clothing layers is given in parentheses)

Required Minimum

Arc Rating of PPE

[J/cm2(cal/cm2)]

0 Non-melting, flammable materials (i.e., untreated cotton, wool, rayon, or silk, or

blends of these materials) with a fabric weight at least 4.5 oz/yd2 (1)

N/A

1 FR shirt and FR pants or FR coverall (1) 16.74 (4)

2 Cotton underwear conventional short sleeve and brief/shorts, plus FR shirt and

FR pants (1 or 2)

33.47 (8)

3 Cotton underwear plus FR shirt and FR pants plus FR coverall, or cotton underwear

plus two FR coveralls (2 or 3)

104.6 (25)

4 Cotton underwear plus FR shirt and FR pants plus multilayer flash suit (3 or more) 167.36 (40)

Note: Arc rating is defined in Article 100 and can be either ATPV or EBT. ATPV is defined in ASTM F 1959-99

as the incident energy on a fabric or material that results in sufficient heat transfer through the fabric or

material to cause the onset of a second-degree burn based on the Stoll curve. EBT is defined in ASTM F

1959-99 as the average of the five highest incident energy exposure values below the Stoll curve where the

specimens do not exhibit breakopen. EBT is reported when ATPV cannot be measured due to FR fabric

breakopen. (APTV = Arc Thermal Protective Value)

AF Testing & Models

To date, there are no practical theoretical models that match tested arc flash results

Instead, state-of-the-art techniques use empirical models based upon test results

IEEE 1584-2002 gives an empirical model that, if properly applied, gives 95% confidence that calculated PPE will be adequate or more-than-adequate for hazards associated with heat energy from an arc

Other effects, such as pressure-wave effects and the effects of the expulsion of molten metal, are not taken into account in the IEEE-1584 model.

IEEE 1584 Model

Ia is the arcing current (kA), defined by IEEE-1584 as:

K = -0.153 for open configurations, = -0.097 for box configurations Ibf: Bolted fault current for three-phase faults (symm. RMS) (kA) V: System voltage (kV) G: gap between conductors, (mm) Represents current that would flow through the arc during

an arcing fault typically 50% - 60% of bolted fault current for 480V system

bfIlogG00304.0bfIlogV5588.0G000526.0V0966.0bfIlog662.0K10aI

En is the normalized incident energy

K1 = -0.792 for open configurations, = -0.555 for box configurations K2 = 0 for ungrounded or HRG systems, = -0.113 for grounded systems Ia is the arcing current (kA) (Calculated) G is gap between conductors, (mm) (Measured) Represents arc-flash incident energy normalized to a

working distance of 610mm and 0.2s arcing time

G0011.0Ilog081.1KKn

a2110E

IEEE 1584 Model

E is the calculated incident energy

Cf = 1.5 for voltages 1kV, = 1.0 for voltages > 1kV t: Arcing time in seconds D: Working distance (mm) x: Distance exponent (tabulated in IEEE 1584) Note that once E is calculated, the process should be repeated but for Ia =

85% of the calculated value. The larger of the two values for E is the calculated arc-flash incident energy.

(cal/cm2)

x

x

nfD

tECE

610

2.0

IEEE 1584 Model

What System Parameters Can be

Changed to Reduce AFIE? From IEEE 1584 model:

System Voltage Bolted fault current Gap between conductors Arcing time

System voltage: Generally not practical to change

Gap between conductors: Would require different equipment construction, not practical to change

That leaves bolted fault current and arcing time.

Effect of Changing Bolted Fault Current

on AFIE Lower bolted fault current leads to

lower arcing current

Arcing current determines arcing time!

Overcurrent protective devices, which define the arcing time, may take longer to trip with lower arcing current due to inverse time-current characteristics

Higher arcing current: 0.06s arcing time

Lower arcing current: 1s arcing time

Arc Flash Mitigation Methods


Number of arc flash explosions that occur in

electrical equipment every day in the United States - According to statistics compiled by Cap-Schell, Inc.,

a Chicago-based research and consulting firm that

specializes in preventing workplace injuries and deaths

5-10

Each year the number of patients that are

emitted to burn centers due to arc flash events - Report by research on IEEE Website

2000

Electrical Safety

Electrical Safety Then and Now http://esfi.org/index.cfm/page/Electrical-Safety-Then-and-Now/cdid/12394/pid/10272

Workplace Electrical Injury and Fatality Statistics http://esfi.org/index.cfm/page/Workplace-Electrical-Injury-and-Fatality-Statistics,-2003-

2010/cdid/12396/pid/3003

http://esfi.org/index.cfm/pid/11506

Arc Flash Mitigation Solutions

Prevention / Avoidance

Passive Containment

Energy Redirection

Installation Considerations

Plenums (ductwork)

Size of Equipment

Equipment location

Passive Protection

Virtual Mains

Zone Selective Interlocking

Bus Differential Relays

Low Arc Flash CB

High Resistance Grounding

Arc Flash Sensing Relay-

VAMPTM technology

Active Protection

LV Arc Flash Sensing Relay

with Arc Quenching technology

MV Arc TerminatorTM

Interactive Protection

Energy-Reducing

Maintenance Switches

System Design

De-energize Equipment

Site Safety Procedures

Intelligent MCCs

AF Mitigating Features (Equipment Design)

Electric Operated CBs

AF

19

Zone Selective Interlocking

Bolted Fault Current 62kA Arc Fault Current 29kA Incident Energy 24 3.33 cal/cm2

PPE Category 1

Bolted Fault Current 62kA Arc Fault Current 29kA Incident Energy 24 3.33 cal/cm2

PPE Category 1

.1sec

10kA 100kA

1sec

10sec

100sec

1kA

M1 3000A

tSD .3 Sec

F1 800A

F2 800A

F3 800A

F4 800A

No restraint signal

Short time delay will be

ignored

Incident Energy 24 20 cal/cm2

PPE Category 3

Bolted Fault Current 62kA Arc Fault Current 29kA

Coordinated System

Arc flash detection relay (1-2 msec) (light sensors/current-optional) Tripping of upstream breaker Fault location identification Multiple zones protection (optional)

MAIN CB

CB F1 CB F2 CB F3

Transformer

Primary fuse

LV Switchgear

x Fault

AF

Relay

Zone 1

Z2 Z3 Z4 Optional

Arc Flash Relay Systems

Typical System Design

Virtual Main

Arc Terminator System Operation Sense a Fault Current + Detect an Arc = Close Shorting Switch

MasterClad Arc Resistant Ratings

Nominal Voltage 4.16 kV 7.2 kV 13.8 kV

Maximum Voltage 4.76 kV 8.25 kV 15.0 kV

BIL (kV) 60 95 95

Continuous

Current (A)

1200, 2000,

3000(*)

1200, 2000,

3000(*)

1200, 2000,

3000(*)

Interrupting

Current (kA)

40, 50 40 25, 40, 50

Internal Arc

Current (kA)

Up to 63, 0.5 sec Up to 63, 0.5 sec Up to 63, 0.5 sec

Enclosure Types Nema 1 Nema 1 Nema 1

(*) Only for 1 High

Pressure Relief Flaps

Arc Plenum - Optional

Medium Voltage MCC

Compartmentalized

Construction

Bolted Rear Panels

Top View

Rear View

Interlocked rear panel to Frame Construction

Top and Bottom Access Panels

Easy Removal

Enclosure AR Type 2

ANSI C37.20.1 Power-Zone 4 Drawout Switchgear ANSI C37.20.7, Annex D Arc Resistant (ANSI C37.20.1 Power-Zone 4 Drawout Switchgear)

North America

Low Voltage Arc Resistant Offer

Schneider Electric SpecTech 2012, November Update 28

IIEEE C37.20.7-2007

IEEE guide for testing metal-enclosed switchgear rated up

to 38 kV for internal arcing

faults

A procedure for testing and evaluating the performance of

metal-enclosed switchgear for

internal arcing faults is

covered. A method of

identifying the capabilities of

this equipment is given.

Service conditions,

installation, and application of

equipment are also discussed.

Without ArcBlokTM

(1 shot) at 65 kAIR @ 480 Vac

AR LV Equipment- Design Values

With ArcBlokTM

(1 shot) at 65 kAIR @ 480 Vac

AR LV Equipment- Design Values

Schneider Electric SpecTech 2012, November Update 31

Testing Standard

Reinforced, Compartmentalized Enclosure

Ratings Bus and Breaker kAIR Accessibility Type (2A/2B)

Optional Features Insulated Bus Plenums Zone Selection Interlocking High Resistant Grounding Energy Reduction

Maintenance Switch

Breaker Remote Racking

Arc Resistant Considerations

Air Intake Design

Optimized Air Flow

Dynamic Spring Loaded Pressure Flap

Plenums

Plenums for PZ-4

What is the Standard for Low Voltage

Motor Control Centers?

Low Voltage Motor Control Center A Standard Dilemma.Resolved

IEEE PC37.20.7, Draft 6 May 2014, Annex H

Purpose of the Annex is to provide specific information

for test sample configuration,

testing methods, test assessment,

and additional ratings that are

specific to LV MCCs (UL845)

There currently is no standard or guide for testing Low Voltage Motor Control Centers for

internal arcing faults however based on

recent decisions within IEEE, AR MCCs will

now be covered in Annex H of the IEEE

C37.20.7 standard.

The most important test parameters for determining equipment capability

is establishing -

The preferred rated arcing duration test (H.3)

The means of establish an arc to produce enough ionized gas quickly

enough to prevent premature

extinction at lower voltages (H.4)

Current discussions within the working group indicate that the minimum arcing duration test

will be no less than 100 ms

Pull Box

Plenum

Exhaust Options

Baffle

Plenum UL Witnessed

Plenum Design

Top Entry thru Pull Box

Single Plenum

Pull Box

28.5 in

10 ft.

Minimum height from bottom of

section to obstruction above MCC

14.24 in.

Rear Front

Ceiling or obstruction above MCC

Thank You

Appendix

MasterClad Arc Resistant 2-High

Circuit breaker

compartment

Relay & instrument door

Cable

compartment

Main Bus

compartment

MasterClad Arc Resistant with Plenum

Plenum Required if: Ceiling* less than

192 Power Zone Center

Application Exhaust needed from

equipment room 50kA or 63kA rating

(optional use-arc shield)

*As measured from the floor

MasterClad Arc Resistant

Arc Shield

Arc Shield Required if: 50kA or 63kA

rating (optional use-plenum)

Increase likelihood of protection for front, rear, & sides of equipment

ArcBlok Patented Technology Internal Arc Gas Management System

Prevents and

Controls Arcing Cluster Shields

Cradle Barriers

Arc Ventilation

Exhaust Methods - Baffles

Roof Baffles

14 Guage Steel

Exhaust Flap

Louvered

10 ft. Clearence

Ceiling

Base of

Equipment

Internal Arc Gas Management

Shroud Power

Stabs Vertical Bus

Isolation

Ventilated

Mid-Shelf

Model 6 Arc Resistant Highlights

Testing Standard C37.20.7, Annex H

UL Witnessed

Reinforced Enclosure 12 gauge steel Additional hardware Metal Control Station Plate Filter box (VFD) Baffle compartment assembly

Ratings 65 kAIR @ 600 Vac Type 2A 100 ms (Stage 1) 500 ms (Stage 2) 2000A Bus (Stage 1) 2500A Bus (Stage 2)

Additional top

mid bracket

Reinforced door

with hinges

Additional bottom

mid bracket

Clip on Fast

Lead Screws

Metal Control

Station Plate

Filter Box for

Thermal Ventilation

47

References


AT327/July 2013

SE Engineering Services

1910BR1205

Arc Flash Description of Services

SAFARC01R02/12

Industry-Leading Expertise We currently have more than 130 power

system engineers. SE Engineering

Services has completed over 10,000

power system assessments, studies,

and designs including IBM.

Arc Flash Analysis

An arc flash analysis is performed to estimate incident energy levels, to identify

appropriate levels of Personal Protective Equipment (PPE) and to determine flash

protection boundaries at specific points in an electrical distribution system.

The Occupational Safety and Health Administration requires employers to protect

facility workers and contractors from the hazards associated with electrical shock,

arc, and blast. The National Fire Protection Agency, producers of the National

Electrical Code, developed a set of guidelines to assist employers in complying with

OSHA laws in the NFPA 70E, Standard for Electrical Safety in the Workplace.

We offer arc flash analyses based on the results from the Short-circuit and

Overcurrent Device Coordination studies, and are calculated using the

equations provided in IEEE Std. 1584-2002.



April 23, 2014

Terry L. Schiazza

Business Development Mgr.

Seneca, SC Manufacturing Facility

Documents

WWCC Arc Flash Mitigation Atlanta