Understanding Design, Installation, and Testing Methods That Promote Substation IED Resiliency for High-Altitude Electromagnetic Pulse Events Tim Minteer, Travis Mooney, Sharla Artz, and David E. Whitehead Schweitzer Engineering Laboratories Copyright SEL 2017
Analyze HEMP Effects, Assess the Risk, Assist Policy Makers and Grid Operators
High-Altitude Electromagnetic Pulse HEMP 1 High-altitude nuclear explosion creates gamma rays 2 which strike molecules, releasing electrons. 3 Earth s magnetic field aligns electrons 4 creating an EMP, which may disrupt electronic systems.
Three Stages of EM Waveforms From a HEMP Event: E 1, E 2, E 3 100 kv/m 50 kv/m E 1 + E 2 100 V/m E 100 mv/m E 1 E 2 E 3 100 mv/m 1 ps 1 ns 1 ms 1 ms 1 s 1000 s Time
Only E 1 Waveform Has Potential to Damage Substation IEDs EM Waveform (HEMP) Duration Similarity to Natural Phenomena Concern for Substation IEDs E 1 : Short-Duration Electrostatic Discharge Yes E 2 : Intermediate-Duration Lightning No E 3 : Long-Duration Geomagnetic Disturbance No
The Unknown Effects of RF E 1 Concerned Some Policy Makers and Grid Operators E1(t) (kv/m) 50 40 30 20 10 23 ns 2.5 ns rise time 0 0 10 20 30 40 50 60 Time (ns) 100 khz 100 MHz AM: 535 1700 khz FM: 87.5 108 MHz Thousands of times greater than EMC RF immunity levels
MYTH: HEMP Could Cause a Protracted Nationwide Blackout
FACT: Robust, Substation-Hardened IEDs Are HEMP Resilient in Substation Control Houses
IEEE and IEC Standards Mitigate EMC Effects Protect cables originating from beyond the substation yard fence E 1 H 1 Control houses constructed from concrete panels with metal liners attenuate > 20 db E 1 H 1 Yard Equip. Yard Equip. Shielded transformers and transient protection attenuate > 40 db (IEEE 1100) E 1 H 1 Conducted disturbance on shields Use substationhardened IEDs IED IED IED Route internal signal wiring along grounded structures Substation Control House Signal wires routed in metal conduits or shielded cables grounded at both ends and 4/0 wires with multiple ties to ground grid (IEEE 525)
Similar Mitigation Techniques of Hardened IEDs Fiber-optic cables provide IED serial communication outside the control house Chassis and metal shields attenuate the RF E 1 waveform E 1 H 1 PTs, CTs, I/O EN, USB, EIA-232, 4 20 ma... E 1 H 1 Shielded, grounded cables protect low-level signals (IEEE 525) Transformers and isolation barriers protect integrated circuits IC IC IC Ground planes and multiple ground points minimize all EMC effects Substation engineers route signal wires along metallic grounded framework inside the control house reducing loop area Substation-Hardened IED
MIL STD 188-125A Is Not an Appropriate Standard Applies to Military Facilities Performing Critical Time-Urgent Missions
Power substations, power generation facilities, and electrical and electronic equipment intended for use indoors Use IEC Standards to Assess Substation IEDs IEC Subcommittee 77C High Power Transient Phenomena of human origin (including HEMP) 21 Publications 1996 present
IEC Substation EMC Immunity Levels Exceed HEMP Resiliency Levels Electrical Fast Transient / Burst Surge Damped Oscillatory Wave HEMP EMC HEMP EMC HEMP (fast) EMC (slow) I/O Power (dc) 2 kv 4 kv 1 kv 4 kv 2 kv 2.5 kv Serial Comm 1 kv 2 kv 2 kv 1 kv 1 kv
Evaluation of Existing Substation Designs Concluded That Substation-Hardened IEDs Are HEMP Immune in Legacy Substations
Substation Designs That Provide Lightning Resiliency Also Provide HEMP Resiliency Lightning EMP RF E 1 Waveform Electric Field 100 kv/m 50 kv/m Rise Time / Pulse Width 10 / 350 ms 2.5 / 23 ns Energy 250 mj 0.7 mj
IEEE Standards Form the Basis of Legacy Substation Design Practices Cables originating beyond the substation yard fence have always been wellprotected from severe EM effects E 1 H 1 Control house material provides 0 20 db of attenuation E 1 H 1 Yard Equip. Yard Equip. E 1 H 1 Substation-hardened IEDs withstand conducted disturbance on signal wires IED IED IED Routed internal signal wiring along grounded structures Signal routing in trenches within a few feet of the ground grid reduces coupling and induced voltages Substation Control House
Mother Nature Doesn t Read Standards Margin Testing Ensures EMC Immunity
Substation-Hardened IEDs Exceed ESD Immunity Requirements Air ESD Contact ESD HEMP 8 kv EMC 8 kv 6 kv S-H 15 kv 8 kv
Most Regions Will Experience Less Than E 1 Max 5.0 kv/m 12.5 kv/m 25.0 kv/m 37.5 kv/m 50.0 kv/m 25.0 kv/m Nuclear Environment Survivability U.S. Army. Report AD-A278230 (1994)
Signal Wire Alignment, Incident Angle, Monopole Height, and Wire Length Affect Coupling E 1 H 1 y F Ground Plane
Probability Density (% / kv) Coupled Transient Voltages From the RF E 1 Waveform Are Statistically Less Than 4 kv 40 30 20 10 0 0 4 8 12 16 20 IED Signal Wire Terminal Peak Transient Voltage (kv) Random variables Location under burst Signal wire alignment Monopole height Signal wire shielding
IEDs Have an Implied HEMP Withstand 3x Greater Than Their Rated Impulse Withstand IED Withstand Voltage Limit Percentage of Installed IED Signal Wire Terminals Exceeding Withstand Limit 23 kv (Post 2013 Withstand) 0 % (Withstand > 20 kv Maximum Peak Transient) 16 kv (Pre 2013 Withstand) 0.003 % 8 kv 1.6 % 4 kv 14.3 % 2 kv 40.6 %
Five Immunity Type Tests Demonstrate HEMP Resiliency of IEDs Immunity Type Test (IEC 61000-6-6) EMC Requirement (IEC 60255-26) Radiated Pulse (2.5 / 25 ns) IEC 61000-4-25 Not Required Fast Damped Oscillatory Wave IEC 61000-4-25 Not Required Air ESD (8 kv) IEC 61000-4-2 IEC 61000-4-2 EFT/B (5 / 50 ns) IEC 61000-4-4 IEC 61000-4-4 Surge (1.2 / 50 ms) IEC 61000-4-5 IEC 61000-4-5
Third-Party Testing Confirms Substation-Hardened Relay Immunity to HEMP RF E 1 Max
Third-Party Testing Confirms Relay Printed Circuit Boards Immunity to HEMP RF E 1 Max
Conclusions IEC 61000-6-6 provides the framework for demonstrating HEMP resiliency of substation IEDs Substation-hardened IEDs are HEMP resilient in legacy and new substations as demonstrated by Fast Damped Oscillatory Wave testing HEMP immunity to 50 kv/m, RF E 1 pulse HEMP survivability using air ESD margin testing at 30 kv followed by impulse withstand testing
Conclusions New substation designs provide HEMP resiliency for IEDs meeting IEC EMC and Safety requirements Further testing of similar substation-hardened IEDs is not recommended The effects of HEMP on substation IEDs should no longer concern policy makers, grid operators, and others
The grid is tougher than you think. Edmund O. Schweitzer, III Contact Information Travis_Mooney@selinc.com