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Static Transfer Switches (STS)

LayerZero manufactures the world’s most technologically advanced Static Transfer Switches for data centers, AI infrastructure, semiconductor fabs, and other mission-critical environments. Since 2001, LayerZero Power Systems Static Transfer Switches have been best-in-class in reliability, safety, connectivity, and power quality monitoring.

LayerZero Static Transfer Switch installed in a data‑center
Static Transfer Switches

What is a Static Transfer Switch?

A Static Transfer Switch (STS) is a high-speed switching device that transfers power from a preferred source to an alternate source without interrupting the load. LayerZero eSTS Static Transfer Switches are built to maximize uptime requirements for data centers, AI clusters, semiconductor manufacturing, and mission-critical environments. At the core of the STS is a proprietary upgrade to Dynamic Phase Compensation — a precision timing algorithm unique to LayerZero. Paired with silicon-controlled rectifiers (SCRs), this system achieves sub-4 millisecond transfers with exceptional accuracy, even in the presence of voltage imbalances and phase shifts.

Static Transfer Switch Reliability diagram
LayerZero eSTS architecture eliminates single points of failure while delivering fast source switching.

Why Use a Static Transfer Switch?

  • Prevents Downtime: Automatically switches between multiple power sources during utility failures or power quality fluctuations.
  • Protects Sensitive, Critical Loads: Protects sensitive equipment such as servers and industrial equipment from power disruptions and quality issues.
  • Perform Maintenance: Dual‑source architecture allows planned maintenance without shutting down the load.
  • Improve Power Reliability: Strengthens the reliability of your electrical infrastructure by providing redundancy and power path diversity.

Static Transfer Switch Product Catalog

LayerZero Static Transfer Switches
Gray Paint
Black Paint

3-Pole Static Transfer Switches

4-Pole Static Transfer Switches

Download full Static Transfer Switch brochure (PDF)

3-Pole Static Transfer Switches

Product Model Current Voltage # Poles Height (in) Width (in) Depth (in) Weight
250 A 208 V 3-Pole 250 208 3 80" (2032 mm) 36" (914 mm) 36.4" (925 mm) 1350 lbs [620 kg]
250 A 480 V 3-Pole 250 480 3 80" (2032 mm) 36" (914 mm) 36.4" (925 mm) 1350 lbs [620 kg]
400 A 480 V 3-Pole 400 480 3 80" (2032 mm) 47" (1194 mm) 37" (940 mm) 1800 lbs [825 kg]
600 A 480 V 3-Pole 600 480 3 88" (2235 mm) 48" (1219 mm) 37" (940 mm) 1800 lbs [825 kg]
800 A 480 V 3-Pole 800 480 3 80" (2032 mm) 57" (1448 mm) 36" (914 mm) 2150 lbs [975 kg]
1000 A 480 V 3-Pole 1000 480 3 88" (2235 mm) 96" (2438 mm) 40.5" (1029 mm) 3000 lbs [1361 kg]
1200 A 480 V 3-Pole 1200 480 3 88" (2235 mm) 96" (2438 mm) 40.5" (1029 mm) 3000 lbs [1361 kg]
1600 A 480 V 3-Pole 1600 480 3 96" (2438 mm) 90" (2286 mm) 42" (1067 mm) 4,800 lbs [2177 kg]
2000 A 480 V 3-Pole 2000 480 3 96" (2438 mm) 90" (2286 mm) 42" (1067 mm) 4,800 lbs [2177 kg]
3000 A 480 V 3-Pole 3000 480 3 91" (2311 mm) 192" (4877 mm) 57" (1448 mm) 11,200 lbs [5080 kg]
4000 A 480 V 3-Pole 4000 480 3 91" (2311 mm) 192" (4877 mm) 57" (1448 mm) 11,200 lbs [5080 kg]

4-Pole Static Transfer Switches

Product Model Current Voltage # Poles Height (in) Width (in) Depth (in) Weight
250 A 120-208 V 4-Pole 250 120/208 4 90" (2286 mm) 48" (1219 mm) 36" (914 mm) 1600 lbs [726 kg]
400 A 120-208 V 4-Pole 400 120/208 4 88" (2235 mm) 48" (1219 mm) 37" (940 mm) 1600 lbs [726 kg]
800 A 240-415 V 4-Pole 800 240/415 4 88" (2235 mm) 84" (2134 mm) 48" (1219 mm) 3050 lbs (1384 kg)
1600 A 277-480 V 4-Pole 1600 277/480 4 108" (2734 mm) 114" (2895 mm) 55.5" (1410 mm) 5,600 lbs (2540 kg)
2000 A 240-415 V 4-Pole 2000 240/415 4 108" (2734 mm) 114" (2895 mm) 55.5" (1410 mm) 5,600 lbs (2540 kg)
3000 A 277-480 V 4-Pole 3000 277/480 4 89" (2261 mm) 192" (4877 mm) 57" (1448 mm) 11,200 lbs [5080 kg]

Technical Overview of eSTS Static Transfer Switches

  • Ratings: Available from 250 A to 4000 A, with 2-source or 3-source input and 3‑Pole or 4‑Pole configurations.
  • No Single Point of Failure: Designed with full redundancy across control logic, power supplies, and gate drives to ensure continuous uptime, even during component failure.
  • Redundancy Architecture: SMR (Single Modular Redundancy) standard; TMR (Triple Modular Redundancy) available for mission-critical applications requiring the highest reliability.
  • Advanced Dynamic Phase Compensation: LayerZero’s proprietary algorithm precisely times source transfers to eliminate transformer inrush - even during 180° out-of-phase conditions—while staying within ITIC curve limits.
  • Sub-Cycle Transfer Speeds: Transfers typically occur in less than 4 ms.
  • Convection-Cooled Design: Up to and including 1200 A, eSTS units use natural convection cooling—no fans, filters, or fuses, for maintenance-free, long-term operation.
  • Waveform Capture & ITIC Plotting: Every transfer is recorded with pre- and post-event waveform capture. ITIC plots are generated automatically for compliance and diagnostics.
  • SSQM Monitoring: Full power quality monitoring including THD, voltage, current, phase rotation, and alarms—viewable locally or remotely via secure Ethernet, Modbus/TCP, SNMP, and NTP sync.
  • Voice-Guided Bypass: On-screen and audio instructions walk operators through the safe bypass sequence, reducing the risk of human error during maintenance.
  • Sectionalized Design: Power, control, and interface sections are isolated to allow safe service while energized. All maintenance is performed from the front—no side or rear access needed.
  • Safety Features: Includes InSight IR® Portholes for closed-door thermal scanning, dead front hinged doors, polycarbonate status windows, and true front-only access.
  • Seismic Compliance: Cabinets are validated on a three‑axis shake table to meet AC‑156 requirements; floor stand and anchor options are available.
  • Customizable Integration: Optional transformer integration (primary or secondary), subfeed or SafePanel® distribution, custom paint colors, and redundant output breakers are available.

Static Transfer Switches – Frequently Asked Questions

What is a Static Transfer Switch?

A Static Transfer Switch (STS) is a fast, solid-state device that automatically switches power between two or more sources without interrupting the load. It ensures continuous uptime for mission-critical operations like data centers and AI clusters.

How does a Static Transfer Switch work?

It uses silicon-controlled rectifiers (SCRs) and advanced logic to detect power quality issues and transfer the load to an alternate source in under 4 milliseconds.

What is the difference between an STS and an ATS?

STS: Solid-state, very fast transfers (<4ms), no moving parts, ideal for continuous mission-critical power needs.
ATS: Electromechanical, slow transfer, best suited for backup generator use or non-critical loads.

How fast does a LayerZero STS transfer?

Transfers typically occur in under 4 ms.

Why is a Static Transfer Switch used in data centers?

STSs prevent power disruptions that could shut down servers, interrupt AI models, or damage critical infrastructure. They are essential for ensuring continuity in high-availability environments and for performing bypass maintenance.

What sizes are available for LayerZero Static Transfer Switches?

From 250 A to 4000 A, available in both 3-pole and 4-pole configurations. Models support 2-source and 3-source systems.

Do I need a 3‑Pole or 4‑Pole STS?

3‑Pole: For standard grounded-neutral systems.
4‑Pole: For switching the neutral separately—ideal for AI clusters, semiconductor tools, and applications requiring independent neutral control.

Can a Static Transfer Switch be used with a UPS?

Yes. STS units are often deployed in conjunction with UPS systems.

Can I service a LayerZero STS without shutting down the load?

Yes. LayerZero STS units feature a voice-guided bypass that fully isolates control electronics. This allows maintenance while the system remains energized and helps minimize human error.

Static Transfer Switch Terminology

Static Transfer Switch (STS)
A high-speed, solid-state switching device that transfers critical loads between two or more power sources without mechanical components.
eSTS
LayerZero’s advanced Static Transfer Switch, equipped with network connectivity, real-time monitoring, and enhanced safety and visibility features.
Transfer Time
The duration required to switch between power sources—typically less than 4 milliseconds (¼ cycle) in modern STS systems.
Static Switch Quality Monitoring (SSQM)
Continuous monitoring of voltage, frequency, total harmonic distortion (THD), and overall power quality during and after a transfer event.
Triple Modular Redundancy (TMR)
A fault-tolerant control architecture using three isolated logic paths and a voting mechanism to maintain uninterrupted operation, even if one path fails.
Neutral Switching
An essential feature in 4-pole STS designs, allowing the neutral conductor to be switched independently—required for compliance with certain grounding schemes and sensitive loads.
Dynamic Phase Compensation
LayerZero’s proprietary second-generation algorithm that synchronizes source transfers to the optimal phase angle. This eliminates transformer inrush, reduces stress on connected loads, and ensures seamless transfers—even under phase imbalance.

Common Static Transfer Switch Applications

Data Centers

Data Centers

Ensure seamless uptime for hyperscale, colocation, and disaster recovery facilities.

AI Clusters

AI Clusters

Deliver uninterrupted power to high-density GPU and ML compute farms.

Semiconductor Manufacturing

Semiconductor Manufacturing

Maintain flawless power in fabs, cleanrooms, and wafer production lines.

Banking & Finance

Banking & Finance

Millisecond-grade transfer speed for trading floors and secure data vaults.

Aerospace & Defense

Aerospace & Defense

Power radar, avionics, simulation, and mission-critical defense networks.

Broadcast & Entertainment

Broadcast & Entertainment

Keep studios, live productions, and editing bays online without glitches.

Cryptocurrency Mining

Cryptocurrency Mining

Feed massive ASIC/GPU loads with stable, low-impedance power delivery.

Education & Research

Education & Research

Protect sensitive experiments, supercomputing, and digital campuses.

Energy Sector

Energy Sector

Provide secure switching in grid control, solar farms, and wind operations.

Emergency Response

Emergency Response (911)

Maximize availability of public safety infrastructure and communication hubs.

Healthcare

Healthcare

Preserve life-critical systems in hospitals, labs, and remote care platforms.

Information Technology

Information Technology

Assure uptime for ISPs, CDNs, hosting centers, and SaaS platforms.

Retail

Retail

Keep PoS systems, fulfillment centers, and ecommerce infrastructure always-on.

Transportation

Transportation

Enable consistent control in airports, seaports, rail, and traffic systems.

Telecommunications

Telecommunications

Sustain switching centers, IXPs, and cell towers during utility events.

The LayerZero eSTS Maximizes Power Reliability

The LayerZero eSTS is a Static Transfer Switch that seamlessly transfers power between two or three sources without interrupting the critical load. Designed to protect mission-critical environments, the eSTS constantly monitors power quality and initiates transfers instantly when deviations occur.

Built with solid-state SCRs and no moving parts, the eSTS executes transfers in under ¼ of an electrical cycle, preserving uptime for sensitive systems like data centers and AI infrastructure.

LayerZero Static Transfer Switches

Designed for Operator Safety

LayerZero eSTS units feature a sectionalized design, separating monitoring electronics from customer connections. This ensures service and operation can occur safely, with inner dead-front doors remaining closed during use.

Voice-guided bypass, mechanical interlocks, IR windows, and optional INSIGHT IR® cameras help operators conduct routine inspections and maintenance without exposure to live components.

Static Transfer Switch Safety

Built for Low Maintenance

Every eSTS is front-accessible, with input/output terminals at the front-bottom of the enclosure—eliminating the need to reach around or behind. Internal buswork is epoxy-coated and connections are silver-plated for durability and reduced maintenance.

Critical internal joints are permanently brazed, creating a system that is robust, safe, and designed for long-term dependability.

Static Transfer Switch Maintenance

Fail-Safe Topology for Maximum Reliability

Triple redundant power supplies and fiber-optic communications provide isolation and resilience. The eSTS comes standard with SMR (Single Module Redundancy), offering fault-tolerant design with fail-safe control logic.

For the highest reliability, TMR (Triple Modular Redundancy) is available—allowing any single failure to be bypassed automatically, ensuring that power delivery remains uninterrupted.

Triple Modular Redundancy Reliability in a Static Transfer Switch

Eliminates Transformer Inrush

LayerZero’s upgraded Dynamic Phase Compensation algorithm calculates optimal transfer timing at the ideal phase angle. This mitigates inrush current during transfers—even under severe load imbalance conditions.

Waveform capture and integrated ITIC plotting tools visually confirm clean transitions, providing transparency and auditability for every transfer event.

Example ITIC Plot on a LayerZero Static Transfer Switch

Direct Access to Critical Information

Every eSTS comes with a built-in Power Quality Monitoring system. Waveform captures, alarms, and ITIC plots are available locally or remotely—using open protocols.

INSIGHT IR® cameras continuously monitor heat signatures inside the cabinet, providing early detection of potential problems before they cause downtime.

Waveform Capture in a LayerZero eSTS Static Transfer Switch

Seismically Tested for Critical Environments

LayerZero eSTS systems are AC-156 certified using tri-axial shake-table testing. This ensures structural integrity and operational continuity during seismic events.

Hospitals, government facilities, and data centers in earthquake-prone areas depend on this certification to maintain uptime in disaster scenarios.

Seismic Testing an eSTS

Proven Track Record of Reliability

LayerZero has been manufacturing Static Transfer Switches since 2001. With all design and production located in Aurora, Ohio, quality control is deeply integrated into every step of the process.

From hyperscale data centers to military bases, the eSTS has earned trust for its performance, reliability, and serviceability in the world’s most demanding environments.

LayerZero: Powering Excellence with Expertise

Protect your facility with the world’s most technologically advanced Static Transfer Switches

Talk to LayerZero engineers about specifying an eSTS for your next mission‑critical build or retrofit.

Contact LayerZero Power Systems