Product Overview

The Closed Transition Automatic Transfer Switch executes a make-before-break transfer between two independent power sources. By briefly paralleling sources for less than 100 milliseconds when parameters match, it eliminates power interruption during routine generator testing and load retransfer.

Built for critical infrastructure, this unit integrates dual-mechanism mechanical interlocks, microprocessor-based sync-check monitoring, and heavy-duty contactors rated for continuous operation at 100% nameplate capacity. It prevents transient voltage dips and eliminates downtime for sensitive digital loads, server arrays, and life-safety systems.

Technical Specifications

Parameter	Specification Range / Standard
Ampere Rating	200A - 4000A (3-Pole and 4-Pole configurations)
Operational Voltage	Up to 600 VAC, 50/60 Hz
Short-Circuit Withstand (WCR)	Up to 100kA @ 480V with specific fuses or breakers
Overlap Time (Closed Transition)	< 100 milliseconds (configurable window)
Sync Thresholds	Voltage difference < 5%, Frequency difference < 0.2 Hz, Phase angle < 5 degrees
Enclosure Types	NEMA 1, NEMA 3R, NEMA 4X / IP54, IP65 (custom modular steel)
Control Interface	LCD digital controller with Modbus RTU / TCP, Ethernet, SNMP
Operating Temperature	-20°C to +60°C

Key Features

Active Synch-Check Algorithm: Continuously monitors live source voltage, frequency, and phase angle; blocks parallel closure if parameters exceed safe tolerance windows.

Dual Mechanical & Electrical Interlocks: Prevents simultaneous direct connection of utility and generator outside the verified synchronization window, eliminating phase-to-phase short circuits.

Zero-Interruption Testing: Enables utility-to-generator and generator-to-utility testing under full load without dropping downstream power.

Modular Arc-Chute Design: Utilizes high-dielectric, gas-evolving splitter plates to rapidly quench arcs and extend contact life during frequent switching cycles.

Isolated Control Power: Powered by dual independent control transformers to maintain controller operation during deep voltage sags.

Applications

Data Centers (Colocation & Enterprise): Maintains uninterrupted server uptime during mandatory weekly or monthly standby generator load tests.

Healthcare Facilities: Manages critical branch and life-safety power transitions without inducing micro-interruptions in sensitive diagnostic or surgical imaging equipment.

Advanced Manufacturing: Protects PLC-driven automated assembly lines and semiconductor fabrication tools from unexpected voltage dropouts.

Telecommunications Hubs: Secures continuous power for cellular switching stations and broadcast towers.

Customization

We engineer ATS configurations to match specific project electrical schematics and physical constraints:

Enclosure Integration: Custom dimensions, bottom/top cable entry plates, and internal tropicalization coatings for corrosive environments.

Bypass-Isolation Configuration: Optional draw-out or external bypass isolation mechanisms allowing switch maintenance without load disconnection.

Communication Protocols: Integration with custom BMS (Building Management Systems) via BACnet IP, Profibus, or hardwired dry contacts.

Metering Packages: Multi-function power meters (Class 0.5s accuracy) for real-time harmonic, THD, and energy consumption logging.

Manufacturing & Quality Control

Production relies on standardized sheet metal fabrication and precision electrical assembly:

Enclosure Processing: CNC laser cutting and automated bending maintain precise enclosure tolerances (±0.5 mm), followed by electrostatic powder coating meeting ASTM B117 salt spray standards (> 500 hours).

Busbar Fabrication: Oxygen-free high-conductivity (OFHC) copper busbars are CNC punched, silver-plated at joint contact points, and torque-verified using calibrated pneumatic tools.

Factory Acceptance Testing (FAT): Every unit undergoes automated rig testing, including dielectric withstand voltage testing (hi-pot at 2.2 kV), millivolt drop resistance checks across main contacts, and live-source synchronization verification under simulated phase displacement.

Certifications & Documentation

Compliance Standards: UL 1008 (Transfer Switch Equipment), IEC 60947-6-1, CE (for European regional projects), CSA C22.2 No. 178, GB/T 14048.11.

Shipped Documentation Package:

Certified dimensional layout drawings (PDF/CAD)

Electrical schematic and wiring diagrams

Component bill of materials (BOM) with UL/CE manufacturer part numbers

Factory test reports (Hi-pot, contact resistance, and functional sequence test logs)

Packaging & Delivery

Packaging Structure: Units are bolted to heavy-duty fumigation-free plywood skids, wrapped in VCI (Volatile Corrosion Inhibitor) anti-moisture film, and enclosed in heavy-duty export-grade wooden crates.

Component Protection: Delicate control panels and HMIs are lined with high-density EPE foam cushioning to prevent shock damage during ocean or air transit.

Lead Time: Standard configurations ship within 4 to 6 weeks; custom engineered submittals require 8 to 10 weeks following drawing approval.

FAQ

Q: What happens if the generator fails to synchronize with the utility during a closed transition test?

A: If the source parameters exceed the pre-set limits (voltage difference > 5%, frequency > 0.2 Hz, or phase angle > 5 degrees) within a defined timer window (e.g., 3 seconds), the controller automatically aborts the closed transition attempt and defaults to an open (break-before-make) transfer to protect downstream loads from out-of-phase closing.

Q: Is a closed transition ATS permitted by all local utility companies?

A: No. Utility approval depends on local interconnection standards. Many utilities permit closed transition transfers only if the parallel duration is strictly limited (typically under 100 ms) and protected by anti-islanding or grade-specific protection relays. Buyers must verify local utility interconnection rules before specifying.

Q: Can this switch handle motor loads and high inrush currents?

A: Yes. The switch utilizes heavy-duty silver-alloy contacts rated for UL 1008 Total System Load categories, including resistive, tungsten, ballast, and motor loads (up to locked-rotor conditions).

Q: What is required to integrate the ATS into our existing SCADA system?

A: The onboard programmable controller includes standard RS-485 ports supporting Modbus RTU and an optional Ethernet module for Modbus TCP/IP or SNMP protocols, allowing direct integration into facility management software.

Q: How do we request custom wiring schematics or submittal drawings for project bidding?

A: Submit your electrical load requirements, system voltage, control voltage preferences, and enclosure rating needs via our inquiry form. Our engineering team returns standard submittal package drafts within 3 business days.

Q: What is the recommended maintenance schedule for the contact mechanism?

A: We recommend a visual inspection, terminal torque check, and contact resistance measurement annually or after every 50 full-load operations. The modular contact assemblies can be inspected without disconnecting main line busbars in bypass-isolation configurations.

Hot Tags: closed transition automatic transfer switch, China closed transition automatic transfer switch manufacturers, suppliers, factory