📋 Case Study
Hospital Power Systems: Emergency Generator Load Flow Validation
Voltage collapse observed during full transfer test due to motor inrush overwhelming AVR response
🏗️ Project Overview
600-bed Level I trauma hospital in Houston with 4×2.5 MW generators and critical life-support loads
🎯 Challenge
Voltage collapse observed during full transfer test due to motor inrush overwhelming AVR response
🔧 Design Approach
Staged transfer sequencing + dynamic VAR injection via capacitor banks triggered by voltage dip detection
📐 Design Diagram
AI-generated project design illustration
📐 Key Calculations
Motor Inrush kVA per HP
HP × 5 × 1.3
Result: 650 kVA
Caused 11.3% voltage dip on 13.8kV bus
Required VAR Injection to Limit Dip <5%
Q_req = (ΔV × S_sc) / X
Result: 1.8 MVAR
Sized capacitor bank with 200ms response
📊 Results
All critical loads maintained >0.95 pu voltage during transfer; passed Joint Commission inspection💡 Lessons Learned
- •Generator AVR bandwidth insufficient for sub-second motor starts — external VAR support required
- •Load sequencing must respect IEEE C37.102 generator capability curves
✅ Key Takeaways
- 1Generator AVR bandwidth insufficient for sub-second motor starts — external VAR support required
- 2Load sequencing must respect IEEE C37.102 generator capability curves