May 13, 2026

🔌 In this video we explain Instantaneous Overcurrent Protection (ANSI 50 — PHHPTOC) completely — covering definition, working principle, asymmetry factor, setting calculation, and coordination with the 51 IDMT element on a real 11 kV refinery substation motor. ✅ What you will learn: — What Instantaneous Overcurrent Protection (50) means — Difference between 50 (Instantaneous) and 51 (IDMT) — Why asymmetry factor 1.2 × LRC is used in setting calculation — How to calculate PHHPTOC pickup setting — How 50 and 51 coordinate on the Time-Current Characteristic curve — Real Relay Settings: 6.6 × In = 2640 A | 40 ms DT — Engineering insights from Commissioning experience ⚙️ Relay Settings covered: CT Ratio = 400/1 A | LRC = 550% × 291 = 1600 A Asymmetrical Peak = 1.2 × 1600 = 1920 A 50 PHHPTOC Pickup = 6.6 × In = 2640 A | Operating Time = 40 ms DT 🏭 Application: 11 kV Refinery Substation — Medium Voltage Motor Protection 📌 Episode 2 of Motor Protection Relay Series. Subscribe 🔔 ⚠️ DISCLAIMER: The information in this video is provided for educational and informational purposes only. Relay settings shown are for learning purposes and must not be applied directly to any real installation without proper engineering review, site-specific studies, and approval from a qualified Protection Engineer. Always follow applicable local standards, company procedures, and safety regulations. The channel is not responsible for any damage, injury, or loss arising from the use of this content. #InstantaneousOvercurrent #ANSI50 #PHHPTOC #MotorProtection #ProtectionRelay #ElectricalOM #RelayCoordination #RefinerySub station #ElectricalEngineering #CircuitBreaker