Arc Flash Mitigation Technology
by Siemens
Low and Medium Voltage Equipment
Unrestricted © Siemens 2016
usa.siemens.com/oil-and-gas
Topics of Discussion

Bolted Faults Vs Arcing Faults

Applicable Industry Standards

Arc Flash Hazards Terms and Definitions

NFPA and NEC-2015 Changes

Low and Medium Voltage Arc Flash Mitigating Techniques by Siemens

Low Voltage Smart Switchgear

Low and Medium Voltage Arc Resistant Switchgear
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So what causes Arc Flash??

Inadvertent Contact with Live Wires/Bus

Loose connections

Insulation Failure

Poorly maintained equipment

Voltage transients

Unsuccessful Short Circuit Interruption

Animals (squirrels, snakes, etc)
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Difference between Arcing Faults and short circuit
fault?
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•
Expanding plasma creates severe
mechanical, thermal stresses in
equipment
•
On a 3 ft x 4 ft door → 7 tons of
force!
•
Can blow open doors
•
Can burn through enclosures
Magnitude of Forces- Arc Flash Testing MV
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End effects of arc fault event…
Temperature
1740F in 0.1 sec. – curable burn (2nd
degree)
2030F in 0.1 sec. - incurable burn (3rd
degree)
Incident energy
1.2 cal/cm2 - onset of 2nd degree burn
10.7 cal/cm2 - onset of 3rd degree burn
Electrical arc blast (explosion)
“80% of electrically-related accidents &
fatalities involving 'Qualified Workers'
are caused by arc flash/ arc blast.”
(OSHA)
“2,000 workers are treated in
specialized burn trauma centers each
year as a result of arc flash injuries.”
(ESFI – Electrical Safety Foundation
International
“5 to 10 arc flash explosions occur daily
across US.” (NFPA 70E)
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Impacts Productivity!
Arc Flash Mitigation- Applicable Standards
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NFPA 2015 Changes
130.1 Work Involving Electrical Hazards
Normal Operation- Normal operation of
electrical equipment shall be permitted
when all of the following conditions are
satisfied:
a. The equipment is properly Installed;
b. The equipment is properly
maintained;
c.
All equipment doors are closed and
secured;
d. All equipment covers are in place
and secured; and no evidence of
imposing failure.
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NFPA 2015 Changes
130.1 Work Involving Electrical Hazards-Informational Notes:
•
The phrase “properly installed” means that the equipment is
installed in accordance with applicable industry codes and
standards and manufacturers recommendations.
•
The phrase “properly maintained” means the equipment has been
maintained in accordance with manufacture recommendations and
applicable industry codes and standards.
•
The phrase “evidence of impeding failure” means that there is
evidence such as arcing, overheating, loose or bound equipment
parts, visible damage or deterioration.
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NFPA 2015 Changes
130.2 (B) Energized Electrical Work Permit
An energized electrical work permit shall not be required under any of the
following:
•
Testing, troubleshooting and voltage measuring
•
Thermography and visual inspection if the restricted approach
boundary is not crossed.
•
Access and egress to an area with electrical equipment if no
electrical work is being performed and the restricted approach
boundary is not crossed.
•
General housekeeping and miscellaneous non-electrical task if
the restricted approach boundary is not crossed.
•
Where the employer’s arc flash risk assessment required by 130.5
identifies
no arc-flash hazards
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Arc Flash Hazards Identification
Table 130.7 (C)(15)(A) AC Equipment
Section 130.(7)(a) IN No. 2, “It is the collective experience of the
Technical Committee on Electrical Safety in the Workplace that
normal operation of enclosed electrical equipment, operating at 600
volts or less, that has been properly installed and maintained by
qualified persons is not likely to expose the employee to an
electrical hazard.”
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NFPA Section 130.4
Arc Flash Hazard Boundary
Section 130.4(B)
Eliminates the Prohibited Approach Boundary for the shock hazard.
The Limited Approach Boundary is the closest an unqualified person
can approach exposed energized conductors or circuit parts.
The Restricted Approach Boundary is the point at which a qualified
person must wear insulating rubber gloves or take other action to
protect themselves from the shock hazard.
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NEC-2015 Arc Flash Requirements
240.87 Arc Energy Reduction
Where the highest continuous current trip setting for which the actual over current device
installed in a circuit breaker is rated or can be adjusted is 1200 A or higher, 240.87(A)
and (B) shall apply.
(A) Documentation. Documentation shall be available to those authorized to design,
install, operate, or inspect the installation as to the location of the circuit breaker(s).
(B) Method to Reduce Clearing Time. One of the following or approved equivalent
means shall be provided:
(1) Zone-selective interlocking
(2) Differential relaying
(3) Energy-reducing maintenance switching with local status indicator
(4) Energy-reducing active arc flash mitigation system
(5) An approved equivalent means
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Definitions of Arc-Flash Hazard Terms
Arc current - NOT bolted fault current. In a typical 480V system, a bolted fault
current of 50 kA available will result in an arc current of only 26 kA.
• Arc current is used to determine the time for the overcurrent protective device
to clear the circuit.
• Since the time for the overcurrent protective device depends on the value of
current flowing, it could be quite different for an arc than for a bolted fault.
Incident energy-Energy impressed on a body surface by an arc, units in
Calories/cm2. Determined by the three basic elements
• Arc current
• System voltage
• Duration of the arc
Incident Energy is used to determine the hazard category for selection of PPE
(Personal Protective Equipment).
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So what is safe practice?
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Safest method to arc flash hazard..
People make mistakes, that’s why we
call them accidents.
Overcurrent Protective Devices can
fail, PPE can fail and even enclosure
can fail.
Increasing working distance is the
best, safest, most fool proof and in
many cases the most cost effective
mitigation method.
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Low and Medium Voltage
Arc Flash Mitigation Techniques
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usa.siemens.com/oil-and-gas
Arc Flash Hazard Solutions Group into Four
Categories
Arc Flash Incident Prevention
Arc Flash Incident Energy Reduction
•
Insulated bus bar
•
Dynamic Arc Flash Sentry
•
Isolation barriers
•
Zone selective interlock
•
Breaker shutters
•
High resistance grounding
•
Infrared viewport
•
Differential relaying
•
Breaker and cradle temperature
monitoring
•
Crowbar systems
Arc Flash Incident Energy Containment
Arc resistant Switchgear
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•
Arc flash light detection
Enabling Personnel to Stay Outside the
Arc Flash Hazard Boundary
• Remote power monitoring, control &
diagnostics
•
Remote breaker operator panel
•
Remote breaker racking device
•
Smart Switchgear with HMI
Arc Flash Mitigation
Insulated/Isolated Bus
Bus bars are intimately covered with insulating material
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Arc Flash Mitigation
Insulated/Isolated Bus
Insulating barriers placed enclose each phase bus
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Arc Flash Mitigation
Hot Spot/Loose Connections Monitoring
IR Windows
• IR Windows enable thermal, visual and
corona inspection of live electrical
equipment
• IR Windows are a risk reduction tool,
they cannot provide 100% protection
against all eventualities but do provide
significant reduction in risk of injury by
reducing the triggers of explosions &
providing a level of protection should an
explosion occur
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Smart Switchgear- Digitalization Concept
Cradle and Breaker Temperature Monitoring from
Remote HMI
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Smart Switchgear- Digitalization Concept
Bus Joints Monitoring
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Smart Switchgear- Digitalization Concept
Switchgear Bus Joints Monitoring from Remote HMI
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Smart Switchgear- Digitalization Concept
Switchgear Bus Joints Monitoring from Remote HMI
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Rear view of LVS
with rear doors open
showing Exertherm
IR sensor mounts in
the main bus bar
bolted joint
Smart Switchgear- Digitalization Concept
Cable Connections Monitoring from Remote HMI
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Arc Flash Energy Reduction- Maintenance Mode
“REDUCING THE DANGEROUS ARC FLASH HAZARD IN INDUSTRIAL
FACILITIES “ IEEE Denver Feb’05
Michael Hodder William Vilcheck
Floyd Croyle
David McCue
Member, IEEE Sr. Member, IEEE Member, IEEE Member, IEEE
Eaton Electrical Eaton Electrical
Eaton Electrical Cytec Industries
“Use a temporary “faster” trip time while work is performed. :
A lockout tagout procedure can include the reduction of a protective device
tripping time. The reduced time settings must be returned to the normal time
setting after work is completed. . . . A lockable switch could be used to enable
the faster setting.”
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Arc Flash Energy Reduction- Maintenance Mode
Dynamic Arc Sentry (DAS)
ETU776 Electronic Trip Unit in the WL Power Circuit Breaker
Normal Operation
Parameter A
Maintenance Operation
Parameter B
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Arc Flash Mitigation –Digitalization Concept
Maintenance Mode from Remote HMI
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Arc Flash Mitigation –Passive Safety Design
Arc Resistant Testing- 500ms
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07/200
Page
Arc Resistant Testing- 100ms
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07/200
Page
Arc Flash Energy Reduction
High Resistance Grounding
•
Source
(Wye)
HRG limits ground current to 4-6A in
low voltage system.
AØ
•
•
HRG allows continuous operation of
the system with single phase to
ground.
Limits current to the arcing faults
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BØ
N
HRG
CØ
Arc Flash Mitigation- Digitalization Concept
Dynamic Bus Differential using Smart Switchgear
Typical Bus Differential
Monitor total incoming currents in each phase and current
going out from feeders.
Sensing
Each phase currents are monitored at incoming and at the
load side of feeder breakers using Ragowski Coil sensors..
Analog signals from the sensors will be analyzed with logic
developed in Smart IPC (CPU)
Smart Concept
Deviation in summation will be annunciated as a bus fault.
Fastest Tripping Times- Reduction
in Arc Flash Energy
In such event, main breaker will be tripped within 70-80 ms
Dynamic Bus Differential
Automatically configured for the M-T-M with
Benefits over ZSI
•
•
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Faster tripping times on bus faults
Smart configured
Arc Flash Mitigation- Digitalization Concept
Dynamic Bus Differential using Smart Switchgear
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Arc Flash Detection
Medium Voltage Switchgear
Front and side view
Optical sensors with
wires
Busbar compartment
Breaker
compartment
Cable connection
compartment
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31.03.201
Page
Arc Flash Detection- Medium Voltage Switchgear
Methods of Arc Flash Detection
•
Light only
• Benefits: Extremely fast tripping,
selective (only affected feeder is
tripped if an arc appears in the cable
connection compartment)
• Disadvantages: risk of unwanted trips
(from camera flash etc..)
•
Light and Current
• Benefits: fast tripping, safety against
unwanted trips
• Disadvantages: more wiring required,
limited to 4 feeders maximum (due to
15 sensor maximum per modular relay)
•
Light and Current with Communication
(Binary signal /IEC 61850 GOOSE)
• Benefits: fast tripping, safety against
unwanted trips, no limit on number of
feeders, one arc flash protection
module per switchgear
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Light only
trip time: ~3ms + contact
Light + current
trip time: ~4ms + contact
Personal Safety- minimize
equipment damage
Arc Flash Detection- Medium Voltage Switchgear
Light & Current (with communication)
Binary signal / Goose
Busbar
compartment
Breaker
compartment
Cable connection
compartment
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Feeder 1
Feeder 2
Incoming
Arc Flash Detection- Low Voltage Swtichgear
OPTIONAL
SPOT
SENSOR
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Arc Flash Detection- Low Voltage Switchgear
Fiber Loop- Current and Flash Detection
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Arc Flash Avoidance – WL Remote Breaker Racking
Device
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Arc Flash Avoidance – Digitalization Concept
Remote Breaker Racking from Smart HMI
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Arc Flash Mitigation
Siemens Integrated Electrical-Racking System
Placement of SIERS components
in switchgear cell
B
Control module mounted in
low-voltage area C
C
A
Electrical racking
mechanism A
Power supply module
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B
Control pendant
Medium Voltage Switchgear
External Mounted Remote Racking Device
• Motor drive accessory:
• Installs without tools on mounting
brackets on front door of circuit
breaker compartment
• Secured to mounting brackets with
pins that are attached to motor drive
assembly with lanyards to prevent loss
of pins
• Power cord for connection to user’s
120 Vac duplex receptacle
• Control cable with pushbutton
• Allows operator to control racking from
a distance
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Siemens Digitalization Concept
Low Voltage Smart Switchgear
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Enabling Personnel to Stay Outside the Arc Flash
Hazard Boundary – Remote Operation Panel
Traditional Remote
Control Panel
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3/31/20
Smart LVS Remote
Control Panel
Arc Flash Mitigation – Smart Switchgear
Remote HMI Panel
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Arc Flash Mitigation- Smart Switchgear
Benefits
Safety
•
•
•
Arc Flash Hazard Data and Calculations
Keeping personnel outside for Fire Hazard
Boundary
Remote Control, Configuration and
Monitoring
Reliability/Productivity
•
•
•
•
•
•
•
•
Fault Trends and Reporting
Harmonics Monitoring
Min/Max Power Metering
Monthly/Daily Maintenance Reports
Transformer Monitoring
Fault Annunciation and Diagnostics
Predictive/Preventive Maintenance
Self Diagnostic Data- Breaker Contact Wear
Indication/Temperature/Type of Fault Alarms
Flexibility
•
•
Easy Integration into Upper Level System
One Power System Solution- Potentially
integrate with MV and Motor Control Centers
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The user has the
option to use the
elevation view (shown
here) or the one-line
view (next slide) as
their home page
where they can drill
down to the
embedded intelligent
devices.
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Smart Switchgear Topology
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Breaker configuration
support screens are
shown below.
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Siemens Digitalization Concept
SMART Low Voltage Switchboards
Expanding the platform, same
great features now available in
a switchboard
SMART LVS
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SMART SB Switchboards
Siemens Digitalization Concept
SMART Low Voltage Switchboards
New HMI for Switchboards
Maintain same offering:
WL circuit breakers
Power Meters
Expand offering:
VL electronic circuit breakers 150A-1200A
New modular metering system SEM3
Upstream
PMCS, DCS,
PCS, or SCADA
systems
HMI
PLC
Murray Load Centers
Low Voltage Power Meter
Power
breaker
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SEM3
VL
Switchboard
Branch Circuit
Monitoring
MCCB
(Temp, Humidity, etc.)
Low Voltage
Arc Resistant Switchgear
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Arc Flash Mitigation –Passive Safety Design
Arc Resistant Low Voltage Switchgear
UL Listed performance
tested and classified as
arc resistant in accordance
with ANSI C37.20.7-2007
10 ft ceiling height requirement
No outside venting is needed in
accordance with performance
testing.
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Arc Flash Mitigation –Passive Safety Design
Room & Personnel Simulation
Switchgear Side View
Working
Space
Indicators
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Arc Flash Mitigation –Passive Safety Design
Design Enhancements
Door Gaskets
and Sealing
Trims
Extra Hinges
Thumb Screw
latches added
One Piece
Breaker Door
Enhanced SillChannel
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FRONT VIEW
Arc Flash Mitigation –Passive Safety Design
Design Enhancements
REAR VIEW
Pressure vent in rear top cover
Extra bolts and pressure dams in
rear covers/doors
Rear vent covers extended
for vent flaps
Extra bolts on
end trim sheets
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Sill channel with internal
plenum for arc venting
Arc Resistant Low Voltage Switchgear
Design Enhancements
Type 2A
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Type 2B
Arc Flash Mitigation –Passive Safety Design
Optional Plenum Venting Design
Front Top
Exhaust
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Arc Resistant Low Voltage Switchgear
Industry Recognitions
•
Type 2B Arc Resistant WL Low Voltage
Switchgear
•
Maximum Arcing Short-Circuit Current Rating –
100kA @ 508VAC and 85kA @ 635VAC
•
Maximum Arcing Short-Circuit Current Rating –
100kA @ 508VAC with Plenum Venting
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•
500 ms arcing duration
•
Compliant with IEEE C37.20.7 with UL Witnessed
•
Maximum Amperage – 5000 amps
Medium-Voltage
Arc-Resistant GM-SG-AR
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Arc Flash Mitigation –Passive Safety Design
Medium Voltage and Systems
Air-insulated Switchgear – Type GM-SG-AR
 IEEE C37.20.7-2007, type 2B
 5 kV, 7.2 kV and 15 kV
 Up to 63KA
 Circuit breakers up to 3,000 A self-cooled, 4,000
A fan-cooled
 One- or two-high construction
 Three-cycle interrupting time (optional)
 UL or C-UL Listing available
 Meets ANSI, IEEE and NEMA standards
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Page 65
GM-SG-AR Arc-Resistant Switchgear
Venting of Hot Gases & Arcing Byproducts
Arc venting
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GM-SG-AR Arc-Resistant Switchgear
Exhaust To Safe Location
Shared Plenum SIMOVAC-AR Medium-Voltage Controller,
Transition Section & GM-SG-AR Medium-Voltage Switchgear
• Exhaust duct (plenum) must be
extended to a safe location
• Local building codes to define
safe location
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Page 67
Siemens recommendations:
• Outside the building
• Safe location outside the room
• Safe location inside the room &
closed to personnel for at least
10’ x 10’ area around outlet
Arc Flash Mitigation –Passive Safety Design
Medium Voltage and Systems
Motor Control – SIMOVAC-AR









2.3 kV to 7.65 kV Ratings
NEMA Class E2 controllers
Vacuum contactors 400 A and 720 A
Optional plug-in contactor (400 A)
Up to 3000 A main bus
Up to 50 kA
NEMA 1, NEMA 1A, NEMA 12 and NEMA 3R
Arc resistant type 2B option
Wide variety of applications:
• Full-voltage non-reversing (FVNR)
• Reduced-voltage solid state (SSRV)
• Two-speed two-winding (2S2W)
• Two-speed one-winding (2S1W)
• Reversing
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Page 68
SIMOVAC-AR arc-resistant
SIMOVAC non-arc-resistant
Arc Flash Mitigation –Passive Safety Design
Medium Voltage and Systems
Motor Control – SIMOVAC-AR
Arc-Plenum (Exhaust Duct)
Exhaust System:
 Can be connected to front,
rear, side or top
 Exhaust duct required to vent
gases outside of the
equipment room.
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Page 69
SIMOVAC-AR arc-resistant
PRC
Exhaust
duct (or
plenum)
Arc Flash Mitigation –Passive Safety Design
Medium Voltage and Systems
Motor Control – SIMOVAC-AR
Arc-Plenum Exhaust System With
GM-SG-AR Arc-Resistant Switchgear:
 PRCs coordinated between
GM-SG-AR and SIMOVAC-AR
GM-SG-AR arc-resistant switchgear & SIMOVAC-AR arc-resistant motor control
Exhaust duct
(or plenum)
 Single plenum
 Can be connected to
front, rear, side or top
GM-SG-AR
 Exhaust duct required to vent
gases outside of equipment
room.
Transition section
SIMOVAC-AR
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Arc Flash Mitigation –Passive Safety Design
Medium Voltage and Systems
Motor Control – SIMOVAC-AR
SIMOVAC-AR With Transition Section To GM-SG-AR Arc-Resistant Switchgear
Installed In A Power Equipment Center
Common PRC for SIMOVAC-AR and GM-SG-AR &
single exhaust duct (plenum)
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