The patented SolidGround® neutral blocking device (NBD) is an effective and economical solution to protect the electric power grid from stray DC and Ground Induced Currents (GIC) from Solar Storms (GMD) as well as high altitude nuclear EMP E3.

Simple Circuit:

The patented circuit has 3 parallel paths to ground (no switch between paths) ensuring the transformer is always grounded 100% of the time.

Solid metallic ground:

SolidGround® has a patented method of allowing the transformer to maintain a solid metallic path to ground during normal operation, and automatically blocking GIC (DC) when detected.

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.

Installation

Tested and Proven Technology

SolidGround® has been operating on the U.S. power grid for many years and is performing as designed with no negative effects to the system.  

Over 15 years of development and testing

Janney Report recommends SolidGround®:

U.S. Department of Defense unclassified EMP E3 field strength of 85 V/km

Click reports above to read

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

The new SolidGround® standard model has doubled its blocking capability in order to protect the grid from the effects of ground induced currents (GIC) as a result of “Carrington-level” 100 year solar events and EMP E3.  The SolidGround® modular design allows for additional upgrades in the field to increase its blocking capability even further if desired by the Utility.

2017 EMP Report to the Commission

Testing suggests the need to install Neutral Blocking Devices to block GIC (GMD/EMP E3 protection) prior to installing filters to protect against EMP E1:

“… when we do these [DC] injection tests – the harmonics… were about 50% higher with the EMP [E1] filter in the circuit than without that filter in the circuit…What we have is a filter designed to protect against one challenge [E1 Pulse] that exacerbates the problems due to geomagnetic disturbances.” - Idaho National Laboratory Results, Scott McBride, Dupont Summit: Mitigating High Impact Threats to Critical Infrastructure, December 6, 2013

Blocking GIC from entering our grid prevents the generation of harmonics, eliminating this potential issue with HEMP filters.

solidground® emp UPGRADE:

• E1, E2 and IEMI shielding and filtering.

• Modular capacitor bank add-ons provide blocking protection against very high GIC currents (greater kV DC withstand) induced by the Nuclear EMP E3 pulse.

• 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.

Benefits of SolidGround®

Protects the most critical, costly and long lead items of a Power Grid: High Voltage (HV) / Extra High Voltage (EHV) Transformers, Converter Transformers (HVDC), Generators and High Voltage Circuit Breakers (the “Backbone of our grid”) against the effects of Nuclear EMP E3 and all levels of 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 (specifically, non-3phase/3 limb core form) 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 significant economic loss to customers 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 saturation of transformers and preventing the generation of Harmonics.

  “…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

Enhances the Stability and Reliability of the grid:

• Provides for reliable and safe operation of High Voltage Breakers during a large GMD or EMP event - HV Breakers are not designed for DC current and can be damaged if operated intentionally or automatically with large GIC/DC current across them.

• Prevents transformer half-cycle saturation due to GIC or EMP E3 induced currents as well as stray DC from switching, energization or other system events.

• Prevents harmonic distortion from GIC which is a great challenge for frequency control

• Reduces VAR consumption during GMD & EMP E3 events:

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

  • The important progression towards wind & solar power makes replacement VARs increasingly difficult to find thereby increasing the Grid’s vulnerability to Grid collapse from GMD/EMP events.

  • Solidground® installed across the grid provides for the safe progression towards RENEWABLE Energy without increasing our vulnerability to GMD & EMP events.

• Prevents voltage collapse due to severe GIC

• Simplifies complex utility operating procedures (which may not be effective) for predicted solar storm events (there is no warning with EMP). 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

• 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). It can be used to protect an old existing transformer and then reused on a new replacement transformer.

The bulk power system and its critical components are not designed for DC current (GIC). Blocking DC from entering the AC power grid removes many uncertainties created with large Solar Storms or EMP events.

Features Overview

Robust Design and GRIDSAFE™

• Fully automatic with no operator action required.

• Major components are proven, industry standard, the highest quality, provided by GE, ABB, Hubbell and Schweitzer Engineering Laboratories (SEL).

• SolidGround® provides a hard wired metallic ground path and an effective AC ground through capacitors.

• Components are designed to take multiple faults with no cool down period required.

• Scalable to protect the entire grid against a severe Carrington-level geomagnetic disturbance (GMD) and Nuclear EMP E3.

• Patented Voltage Safety Switch provides transformer protection in scenarios where field strengths experienced are much higher than anticipated.

Schweitzer Control Electronics

• Continuously monitors for DC/GIC currents, harmonics (optional) 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.

• Shielding protection for EMP E1 & IEMI (EMP Upgrade).

The patented SolidGround® circuit and method is the most effective and least intrusive way to block GIC allowing the transformer to maintain its solid metallic path to ground during normal operation (>99.9% of the time) for handling faults or other system events and AC grounded while blocking GIC (<0.1% of the time).

DuraGap® is utilized in the off chance there is a fault or other system event during those brief moments while in the “blocking state”.

DuraGap® Overvoltage Protection

• Robust patented spark gap specifically designed because there was nothing available in the market capable of repeatedly handling the unique combination of voltage and amperage required by utilities during system events.

• Simple, Passive Device/EMP proof (no triggering electronics), Dual redundant.

• In KEMA Lab tests DuraGap® easily carried 20 faults (8 cycles each) with 10 kV breakdown and 56 kA peak (20 kA RMS). Breakdown voltage did not increase due to the patented gap preserving design.

• Built for multiple high fault current and transient voltage events. No cool down period required.

• 56/20 kA rating can be increased as needed by order.

SolidGround® can utilize any surge protection device preferred by the customer to limit voltage stress while in blocking mode during system events.

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."