Geomagnetically/Ground Induced Currents (GICs):

GICs occur in the earth as a result of solar storms, high-altitude nuclear EMP (E3 HEMP) and HVDC operation. These GICs invade the power grid through the transformer neutral wires which are connected into the ground. The greatest threat to our power grid is below our feet.

There are no “operating procedures” that can prevent GIC or the induced harmonics from entering an operating grid. Prediction and detection are not protection.

The patented SolidGround® GIC Blocker, developed in conjunction with the utility industry, is a proven and validated solution to protect the electric power grid from stray DC and GIC from Solar Storms (GMD) and high-altitude nuclear EMP (E3 HEMP).

Independent System:

No tampering with existing AC power system or controls. SolidGround® simply attaches to the neutral wire of a transformer. No customer load flows through device. No negative impact to the power grid. No ferroresonance and no resetting of protection relays required.

Simple Robust Circuit:

The patented circuit was designed with utilities and has 3 parallel paths to ground (no switch between paths) ensuring the transformer has a bolted AC path to grounded 100% of the time. SolidGround® is now IEEE 693-2018 “High Seismic” Certified.

Easy operating modes:

SolidGround® (via local and remote controls) can operate automatically (no operator action required) or manually, giving utilities strategic options on how to best protect their assets.

SolidGround® protects large power transformers and protects the rest of the power grid from those transformers.

Large Power Transformers saturate with GIC and become an active threat to the rest of the power grid as they consume reactive power (VARs) and generate harmonics which continue to grow as they travel into lower voltage, damaging equipment all the way to the load and in severe cases collapsing the grid.

Recent “warning shots” from the sun expose power grid vulnerability to GIC induced harmonics:

In 1989, GIC from a moderate 2 V/km GMD event saturated transformers causing them to consume VARs and induced harmonics severe enough to trip out critical VAR supply - collapsing Quebecs grid in 92 seconds (6 million people without power).

In 2024, NERC reported that GIC from the smaller “Gannon” storm induced “high levels of harmonic currents on the system” which “unexpectedly tripped out voltage support equipment [VAR supply]”. The GICs from this smaller event did not result in enough VAR losses to collapse the grid. The larger the solar storm event (higher V/km), the larger the GICs. As GIC in a transformer increases - the harmonics they inject into the grid increases.

GIC induced Harmonics propagate and are amplified on the low side of saturating Step-Down Transformers - precisely where VAR supply (SVCs) and Data Centers are installed. VAR supply does not have a good track record of being available in smaller 1-2 V/km GIC events (due to harmonics). We cannot assume VAR supply will be available in larger GIC events (20 - 85+ V/km). VAR supply does not protect a grid from GIC or harmonics…it merely supports voltage levels in an attempt to keep the system running as GIC freely enters the power grid - exposing critical grid components to more severe GIC and harmonics over longer durations.

SolidGround® is a grid stability and harmonics mitigation system.

SolidGround® blocks GIC from entering transformer neutral wires - protecting transformers and preventing them from consuming VARs and generating harmonics. Each unit installed decreases Total Network GIC increasing the power grids V/km withstand limit which allows the grid to safely operate through larger GIC events. The first units installed have the greatest Network GIC reduction as you target the largest GIC contributors first. Adding additional units to a system further enhances grid resilience.

“…two dozen GIC blocking devices installed on the ATC system would increase the system withstand from 20 V/km to approximately 27 V/km. This is a considerable increase in resilience for a relatively small investment.” - American Transmission Company

The bulk power system and its critical components are not designed for GIC and the induced harmonics. Blocking GIC from entering the AC power grid removes many uncertainties created with large Solar Storms or high-altitude EMP events.

Installation

Tested and Proven Technology

SolidGround® has been continuously operating on the U.S. power grid for over ten years performing as designed with no negative effects to the system.  

Over 15 years of development and testing

Benefits of SolidGround®

Protects the most critical, costly and long lead items of a Power Grid: Extra High Voltage (EHV) / High Voltage (HV) Transformers (HVDC Converter, GSU, Auto, Step-down), Large Power Generators and High Voltage Circuit Breakers (the “Backbone of our grid”) against the effects of high-altitude Nuclear EMP (E3 HEMP) and severe Solar Storms (GMDs).

Blocks GIC (DC) from invading the AC Power Grid

• Immediate Benefit: Each year, Ground Induced Currents (GICs) invade the power grid through the neutral to ground connection of high voltage transformers. These large power transformers can begin to saturate and generate harmonics due to GIC as low as 2 to 5 amps/phase. These harmonics generated at the high voltage level, build as they travel into the lower voltage distribution network towards load, causing damage and and estimated $10 billion in economic loss in the U.S. each year. SolidGround® Blocks these smaller and more frequent GICs from common low-level solar storms as well as stray DC events (high voltage switching and HVDC operation) preventing the generation of Harmonics.

  “INL and DTRA…first full-scale testing…demonstrated that geomagnetic-induced harmonics are strong enough to penetrate many power line filters and cause temporary resets to computer power supplies and disruption to electronic equipment, such as uninterruptible power supplies.” - Assessing the impact of space weather on the electrical power grid based on insurance claims for industrial electrical equipment, Lockheed/Zurich/NOAA: C. J. Schrijver, R. Dobbins, W. Murtagh, and S.M. Petrinec, Space Weather Journal, 2014

  “…our present study on insurance claims suggests that, for an average year, the economic impact of power-quality variations related to elevated geomagnetic activity may be a few percent of the total impact or several billion dollars annually.” - Assessing the impact of space weather on the electrical power grid based on insurance claims for industrial electrical equipment, Lockheed/Zurich/NOAA: C. J. Schrijver, R. Dobbins, W. Murtagh, and S.M. Petrinec, Space Weather Journal, 2014

  “The overall fraction of all insurance claims statistically associated with the effects of geomagnetic activity is ~4%…an average impact on the order of $10 billion per year…”

  Electrical Claims and Space Weather: Measuring the visible effects of an invisible force, Zurich, June 2015

  “I would like to stress that in addition to these extreme events, smaller but more frequent GMDs are estimated to cause an average of $10 billion in damage each year. Address the major GMDs and we can also protect us from these smaller events.” - Testimony of Dr. Justin Kasper, University of Michigan, U.S. Senate Committee on Homeland Security and Government Affairs, 2019

Prevents the generation of GIC induced harmonics:

• Prevents transformer half-cycle saturation due to GIC as well as stray DC from system events or HVDC operation. Golden Rule - keep GIC below 6 amps in the neutral of the transformer to prevent half-cycle saturation.

• Prevents GIC induced harmonics (Resistors in the neutral do not prevent harmonics)

• Reduces VAR losses during GMD & EMP E3 events:

  • Reduces/eliminates the need to generate replacement VARs during GMD/EMP events in order to prevent Grid collapse.

• Reduces risk of voltage collapse due to severe GIC

  • Operating procedures to supply VARs (utilizing SVCs or turning up generation) to prop up voltage is a dangerous approach for large GIC events - this procedure ensures grid components will experience extreme GIC/harmonics and heating over a longer duration. It is critical to block GIC to protect the power grid and operate through large GIC events while avoiding catastrophic damage to irreplaceable large assets across the grid.

• Proven to simplify and/or replace costly operational mitigations which cannot prevent GIC from entering an operating grid. SolidGround® provides automatic and immediate protection at the precise time and precise location where needed and is not susceptible to human error.

• Reduces misoperation of relays and protective equipment due to GIC related harmonics

• Provides for reliable and safe operation of High Voltage Breakers during a large GMD or EMP event - HV Breakers are not designed to break GIC and harmonic currents and can be damaged in the arcing chamber if operated intentionally or automatically with large GIC + harmonic currents across them.

• Stops existing cumulative GIC stress on transformers and prevents the degradation of transformer insulation. Reduces or eliminates transformer vibration/noise.

• SolidGround® is designed to work on nearly all High Voltage and Converter Transformers (HVDC) designs. It can be used to protect an old existing transformer and then reused on a new replacement transformer.

Janney Report recommends SolidGround®:

U.S. Department of Defense declassifies E3 HEMP field strength - up to 85 V/km for locations in the southern part of the continental U.S., and 102 V/km for locations nearer to the geomagnetic equator.

Click reports above to read

Why the Department of Defense declassified this:

The Department of Defense depends on our electric power grid, yet they do not own or operate these critical assets and so cannot protect them. The GIC threat has been declassified to equip the industry to protect their assets. The Commission Report states: “The best solution is for DoD to share this information with industry to support near-term protection of electric grids and other national critical infrastructures that are vital both for DoD to perform its missions and for the survival of the American people.” - Recommended E3 HEMP Heave Electric Field Waveform for Critical Infrastructures, Report of the Commission, 2017

E3 HEMP Update (May 2025):

International Standard IEC 61000-2-9 Edition 2.0 2025-05: increased peak E3 HEMP to 85 V/km, duration up to 1,000 seconds (~17 minutes)

SolidGround® 4th Generation Model

Completed October 2025

The new SolidGround® model with proprietary GRIDSAFE® technology has enhanced ratings to meet the updated IEC E3 HEMP Standard (61000-2-9 Edition 2.0 2025-05) to protect the grid from the effects of ground induced currents (GIC) as a result of E3 HEMP and extreme Solar Storms much larger than the 1859 “Carrington” Event. The SolidGround® standardized modular design allows for additional upgrades in the field if desired by the Utility. The patented circuit and methods make SolidGround® the only GIC blocker that is scalable (and effective) when installed at many locations across a power grid to protect against extreme GIC events.

SolidGround® Protects the Power Grid from both high altitude Nuclear E3 HEMP and Solar Storms

2017 EMP Report to the Commission

• EMP.Alert® (RF-81) patented EMP mitigation system detects specific EMP E1 frequencies in nanoseconds and triggers SolidGround® into "blocking mode" within 250 milliseconds of the E1 pulse (1 - 2 seconds before the arrival of very large E3 ground induced currents).

• Emprimus® designed and patented the method of utilizing the E1 pulse as a trigger to “island” portions of the electric grid prior to the arrival of the damaging E3 ground induced currents (GICs).

• SolidGround® can also operate in Normally Blocking Mode which places capacitors in the neutral continually during normal operation, automatically bypassing the capacitors only for very short periods when necessary during system events.

Features Overview

Robust Design and GRIDSAFE™

Schweitzer Control Electronics

• Continuously monitors for DC/GIC currents and EMP E1 (EMP upgrade) giving complete visibility into what is happening on the Power Grid.

• Settable thresholds allow for site-specific customization

• Cyber resistant controls, communicates with SCADA

• Allows for alarms, warnings, messages to other systems or sites and logging of GIC activity

• Allows for remote manual control of unit for specific purposes if desired by the utility.

The patented SolidGround® circuit and method is the safest, most effective and least intrusive way to block GIC allowing the transformer to maintain its AC ground 100% of the time.

EMP E3 Pulse

The threat and consequences of a Nuclear EMP attack have been studied since the 1950's (extensive reports published) and have included two formal U.S. Congressional EMP Commissions (reports published in 2004 and 2008).

"Commission analyzed the impact of a 100-year solar storm (similar to E3 from EMP) and discovered a very high consequence vulnerability of the power grid."  

"Steps taken to mitigate the E3 threat also would simultaneously mitigate this threat from the    natural environment."