The Challenge
A 2.1 million square foot automotive assembly plant with three production lines faced critical electrical safety and capacity challenges. The facility's 40-year-old power distribution system serving 847 robotic welders, paint systems, and conveyor lines had arc flash incident energy levels exceeding 55 cal/cm² at main switchgear locations. Production downtime from nuisance trips cost $18,000 per minute, and maintenance workers required excessive PPE that limited their ability to safely perform work. The plant needed to add 8 MW of capacity for a new electric vehicle battery assembly line while maintaining 24/7 production schedules across three shifts.
Our Solution
We developed a phased solution that reduced arc flash hazards by 82% while adding 8 MW of capacity for new EV production lines. Our approach minimized production disruptions by scheduling all work during planned maintenance windows and utilizing mobile substations for seamless equipment transitions.
Key Components
Implementation Phases
Phase 1: Assessment and Planning (Months 1-3)
Comprehensive evaluation coordinated with production schedules and planned shutdowns.
- •Complete electrical system modeling and updated single-line diagrams
- •IEEE 1584-2018 arc flash study for 247 equipment locations
- •Short circuit analysis and protective device coordination study
- •Power quality assessment at robotic welding cells
- •Equipment condition assessment via thermography and testing
- •Production-synchronized implementation schedule
- •Temporary power solutions for continuous operation
- •UAW coordination and safety committee briefings
Phase 2: Immediate Arc Flash Reduction (Months 4-7)
Quick-win safety improvements requiring minimal downtime.
- •Installation of maintenance mode switches on main switchgear
- •Zone-selective interlocking between 34 circuit breakers
- •Optimized relay settings reducing clearing times
- •Current-limiting fuses at 18 high-energy locations
- •Arc flash warning labels on all 247 equipment locations
- •Updated safe work procedures and energized work permits
- •NFPA 70E training for 142 electrical maintenance personnel
- •New arc-rated PPE kit distribution
Phase 3: Major Equipment Replacement (Months 8-14)
Systematic switchgear replacement during scheduled plant shutdowns.
- •Replacement of main 15kV switchgear with arc-resistant design
- •Installation of two new 5 MVA unit substations for EV line
- •Upgrade of 12 motor control centers serving robotic cells
- •Harmonic filtering for VFD-heavy welding operations
- •Mobile substation deployment during transitions
- •New protective relay installation with Ethernet communications
- •Integration with plant SCADA and energy management systems
- •Voltage regulation improvements reducing flicker by 67%
Phase 4: Testing, Training, and Commissioning (Months 15-16)
Comprehensive system verification and workforce readiness.
- •NETA acceptance testing on all new equipment
- •Updated arc flash study showing 82% incident energy reduction
- •Final protective coordination verification
- •Power quality validation at critical production equipment
- •Load testing of new EV line substations at 110% capacity
- •Complete arc flash label updates with current calculations
- •Advanced NFPA 70E training including hands-on simulations
- •As-built documentation and digital twin model
Results & Impact
Incident energy reduced from 55 cal/cm² to 9.8 cal/cm² at main switchgear, eliminating Category 4 PPE requirements and enabling faster, safer maintenance work.
Nuisance trips eliminated entirely, improving line availability from 94.7% to 99.94% and avoiding $4.2M in annual downtime costs.
Successfully added 8 MW for new EV battery assembly line supporting 120,000 units/year production target.
Zero unplanned production stoppages during entire 16-month upgrade despite 24/7 manufacturing operations.
Client Testimonial
"ClarkTE understood the realities of 24/7 automotive production. They coordinated every outage with our planned maintenance windows, used mobile substations to keep lines running during switchgear replacement, and delivered an 82% arc flash reduction without a single minute of unplanned downtime. Our electricians can now safely maintain equipment without the bulky Category 4 suits that used to slow everything down. This project directly enabled our EV expansion."
Technical Details
Equipment Installed
- ▸15kV arc-resistant switchgear (5000A) with pressure relief plenum
- ▸(2) 5 MVA pad-mount transformers (15kV/480V) for EV battery line
- ▸(12) Motor control centers (1200-2500A) with maintenance mode switches
- ▸600 kVAR active harmonic filter for robotic welding VFDs
- ▸Zone-selective interlocking across 34 circuit breakers
- ▸(18) Current-limiting fuses at high-energy locations
- ▸SEL-751A feeder protection relays with Ethernet communications
- ▸Mobile 3 MVA substation for seamless equipment transitions
Protection Improvements
- ▸Reduced maximum incident energy from 55 to 9.8 cal/cm²
- ▸Improved coordination selectivity from 61% to 97%
- ▸Reduced average clearing time from 0.45s to 0.067s (85% reduction)
- ▸Eliminated 34 mis-coordinated breaker pairs
- ▸Added ground fault protection on all 480V feeders
- ▸Integrated with plant SCADA for real-time fault monitoring
Standards and Codes
- ▸IEEE 1584-2018 (Arc Flash Hazard Calculation)
- ▸NFPA 70E-2021 (Electrical Safety in the Workplace)
- ▸NFPA 70 (National Electrical Code)
- ▸NETA ATS-2019 (Acceptance Testing Specifications)
- ▸IEEE 519-2014 (Harmonic Control)
- ▸OSHA 1910 Subpart S (Electrical)
- ▸ANSI C37 standards (Switchgear and Relays)
Lessons Learned
- Close collaboration with UAW safety committee and production supervisors built trust and buy-in from the start
- Mobile substations enabled switchgear replacement during planned shutdowns without production impact
- Detailed coordination with production scheduling 6 months in advance ensured zero conflicts
- Pre-fabricating all panels and assemblies off-site minimized field installation time
- Weekly toolbox talks with electricians maintained safety awareness throughout the project
- Power quality improvements (harmonic filtering, voltage regulation) reduced robot re-work rates by 12%
- Implementing zone-selective interlocking first provided immediate arc flash reduction before major equipment replacement
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