NERC Releases Incident Reports Highlighting Lessons Learned
In January 2026, NERC issued two incident reports regarding sudden load reductions at large facilities. In both cases, the sudden load loss was linked to blockchain/crypto-mining facilities shutting down during temporary voltage dips caused by grid faults. If blockchain/crypto mining load continues to grow, this type of large load loss could grow to become a reliability concern.
To better understand the ride-through characteristics of these blockchain/crypto-mining facilities, NERC held discussions with the facility owners and operators. TRC clients are advised to review the two incident reports and consider the concentration of this type of facility in their service areas.
Why Crypto-Mining Facilities Fail to Ride Through Down During Voltage Dips
Crypto-mining facilities depend on a large number of constant-power electronic power supplies that are sensitive to voltage drops. When the voltage dips below a certain threshold, the facility controls shut down almost instantly, causing a rapid loss of load. During a voltage depression or sag (for instance due to typical lightning strike or equipment short circuit), the amount of current drawn by a constant-power load will be inversely proportional to the reduction in voltage. Depending on how heavily loaded the circuits are, the increase in current due to the voltage depression could result in overload and trip local protection systems.
Once the voltage recovers, crypto-mining facilities go through a potentially lengthy multistage restoration process, which includes stabilizing the power supply, booting the operating system, initializing the mining software, recognizing hash boards, and normalizing the cooling system. Consequently, restoration times can vary from just a few minutes to significantly longer depending on the type of equipment, the cooling system, and whether manual resets are required. Unlike traditional data centers, crypto-mining facilities do not return to full load almost immediately; instead, their ramp-up process is gradual and predictable, reducing the chances of rapid spikes in demand on the grid.
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Recommendations for Utilities and Operators
TRC clients are encouraged to review both incident reports and assess the concentration of crypto-mining facilities in their service areas.
NERC identified several areas for further review and improvement:
- Review neutral overcurrent protection schemes. Single-phase voltage depressions create significant current imbalance, causing neutral overcurrent relays to trip entire facilities. Transitioning to ground overcurrent protection may help distinguish true ground faults from temporary phase imbalance events.
- Understand impacts of transformer configurations. Transformer winding design affects how voltage sags are passed to loads. Delta-wye transformer stages help “temper” single-phase voltage depressions, reducing load-loss risk. Transformer winding configuration should be evaluated at new facilities with a focus on limiting impact of voltage depressions during system faults. Transformer winding configuration should be evaluated at new facilities with a focus on limiting the impact of voltage depressions during system faults.
- Incorporate constant-power device behavior into event modeling. Crypto-mining power supplies increase current during voltage depressions, contributing to overcurrent trips. Future system models and protection studies need to reflect this constant-power response during grid faults. Crypto facility owners should account for this increase in current during system fault-induced voltage depressions to avoid overcurrent tripping of facility devices during normally cleared system faults.
- Strengthen cooling-load ride-through coordination. Variable Speed Drive (VSD) and Variable Frequency Drive (VFD) motor driven cooling equipment have shown overly sensitive undervoltage trip settings (e.g., 0.96 p.u.), causing entire facilities to drop for faults that clear normally within milliseconds. Crypto-mining facilities should reassess protection settings and consider UPS support for cooling controls.
- Study and track restoration-time variability. Crypto-mining facilities recover through staged boot processes rather than instantaneous UPS-backed restoration.
- Prepare to update interconnection requirements for evolving load types. As some crypto facilities transition toward AI or cloud workloads, load behavior, ride-through characteristics and use of UPS systems may change.
Next Steps: TRC Can Help
Clients should proactively evaluate the concentration and characteristics of large constant-power loads within their service territories and assess how these facilities perform during voltage disturbances. Early coordination with facility owners, along with updated modeling and protection reviews, can help reduce the risk of unexpected load loss and improve overall system reliability.
TRC helps utilities, cooperatives and facility owners assess and manage the reliability impacts of large crypto-mining loads. Our team can:
- Review NERC incident findings and evaluate applicability to your system
- Assess protection schemes, including neutral and ground overcurrent coordination
- Perform load modeling that reflects constant-power device behavior during voltage depressions
- Evaluate transformer configurations and fault performance
- Review cooling system ride-through settings and restoration characteristics
- Support interconnection studies for new or expanding large loads
By combining system studies, protection reviews and operational guidance, TRC helps clients reduce the risk of sudden load loss and improve overall grid reliability.
Resources
NERC Incident Review: Considering Simultaneous Voltage-Sensitive Load Reductions
NERC Incident Review: Considering Simultaneous Voltage-Sensitive Load Reductions January 9, 2026
NERC Incident Review: Considering Simultaneous Voltage-Sensitive Load Reductions
January 8, 2025
About TRC’s System Studies Practice
TRC’s approach to power system compliance planning practice balances solutions that incorporate appropriate standards, regulatory requirements, best practices and operational goals and budgets. Our work for public and private sector utility clients is a testament to our understanding of NERC compliance related aspects of your business. Our successful application of technology solutions in a constantly evolving business and regulatory landscape will provide you with confidence regarding your power system compliance programs. Our power system experts help you stay ahead of changing operations and regulatory expectations because they stay engaged with the regulatory process and know how to plan, design and install programs that address your financial, technical and scheduling goals including compliance with changing NERC standards and guidelines as well as industry “best practices” and the latest technology developments.
This regulatory update is a service to TRC’s utility clients, helping keep you informed of issues that increase your company’s electric compliance risks along with related topics regarding future regulatory developments to help you achieve your company’s business goals.
