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SBU-AT 208V-480V Circuit Breaker Based Automatic Transfer Switchboard

208V, 480V, 600V Switchgear-Style Automatic Transfer Switchboard with Insulated Case Circuit Breakers

SAFE  SMART SERVICEABLE SECURE SWITCHBOARD

The SBU-AT combines the functionality of the Switchboard and Automatic Transfer Switch. The APT Automatic Transfer Switchboard (ATSB) is an Insulated Case Circuit Breaker based load transfer switchboard used to integrate a generator set into your power distribution system, without continuous paralleling with the utility.

Automatic Transfer Switchboard

Redundant Bypass Isolation

For applications when down time is not an option for your ATSB, the APT Redundant Bypass Isolation ATSB combines the functionality of the Automatic Transfer Switchboard with the additional redundancy of bypass circuit breakers.

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SBU-AT

Automatic Transfer Switchboard

208V - 600V Circuit Breaker-Based Load Transfer

Low-voltage automatic transfer switchboard integrating utility and standby generator sources with circuit-breaker switching, protection, metering, and system control.

SBU-AT circuit breaker based automatic transfer switchboard
View Brochure Request a Quote View Specifications
Voltage Range
208V - 600V, 3Ø
Main Bus
Up to 4000A
Transfer
Open / Closed
Switching
Circuit Breaker Based
Enclosures
NEMA 1 & 3R
Standard
UL 891 Listed

Key Specifications

Voltage
208V - 600V, 3Ø
Main Bus
Up to 4000A
Transfer
Open / Closed
Switching
Circuit Breaker Based
Enclosures
NEMA 1 & 3R
Standard
UL 891

Overview

The SBU-AT combines low-voltage switchboard distribution and automatic source transfer in a single circuit-breaker-based lineup.

When normal utility power is unavailable, the transfer control system can automatically start the standby generator and transfer facility loads to the alternate source.

Open- and closed-transition operation, source protection, metering, controls, communications, and feeder distribution can be incorporated around the requirements of the power system.

Explore Transfer Operation

Standard Construction

SBU-AT circuit breaker based automatic transfer switchboard
  1. 01 Circuit-Breaker-Based Source Switching
  2. 02 Silver-Plated Copper Main Bus
  3. 03 NEMA 1 or NEMA 3R Construction
  4. 04 Integrated Automatic Transfer Controls

Final lineup and component arrangement vary by project requirements.

Why It Matters

Automatic Standby

Detects loss of the normal source and coordinates generator start and load transfer.

Transition Options

Open- and closed-transition configurations support different transfer requirements.

Integrated Protection

Source monitoring, circuit protection, metering, and controls are integrated within the switchboard.

System Integration

Controls, metering, communications, and feeder distribution can be combined into one lineup.

How It Works

SBU-AT automatic transfer operation Utility and standby generator sources connect to the SBU-AT automatic transfer switchboard, which transfers power to facility loads. UTILITY Normal Source GENERATOR Standby Source SBU-AT AUTOMATIC TRANSFER SWITCHBOARD FACILITY LOAD Distribution / Feeders AUTOMATIC SOURCE SELECTION TRANSFERRED LOAD

The SBU-AT monitors the normal utility source. If acceptable utility power is lost, the control system initiates standby generation and transfers the facility load to the generator source.

When normal power returns, the system transfers the load back to utility according to the selected open- or closed-transition sequence.

View Transfer Operation Explore Transfer Operation
SBU-AT circuit breaker based automatic transfer switchboard

Need Help Configuring Your Transfer Switchboard?

SBU-AT systems can be configured around the electrical, transfer, and control requirements of the application. Our sales team can help determine the appropriate ratings, transition method, source arrangement, and control options for your facility.

Voltage Bus Ampacity Transition Type Service Entrance Controls

Our team can help with:

  • Application review
  • Open or closed transition selection
  • Source & breaker configuration
  • Control & monitoring options
Talk to a Product Specialist

Technical Specifications

Voltage
208V–600V, 3Ø, 3 or 4 wire
Current Rating
Up to 4000A
Transfer Transition
Open or closed transition
Switching Method
Circuit breaker based automatic transfer
Enclosures
NEMA 1 indoor / NEMA 3R outdoor
Bus Material
Silver-plated copper
Service Entrance
Available as required by NEC
Generator Protection
Overcurrent, voltage & frequency protection
Communications
SCADA-ready Modbus available
Listing
UL 891 Listed low-voltage switchboard

Applications

Automatic transfer solutions for standby power, service entrance, and integrated facility distribution.

Automatic Standby Power

Automatically transfers facility loads to standby generation when acceptable utility power is unavailable.

Utility-to-Generator Transfer

Supports open- or closed-transition transfer between the normal utility and standby generator sources.

Service Entrance Applications

Available for service-entrance applications where the transfer switchboard also serves as facility service equipment.

Integrated Facility Distribution

Feeder circuit breakers can be incorporated so transfer and downstream distribution are combined within one switchboard lineup.

Final transfer sequence and system configuration depend on facility requirements and electrical system design.

FAQ

What is the SBU-AT?

The SBU-AT is a circuit-breaker-based low-voltage automatic transfer switchboard that combines source transfer, protection, controls, and facility distribution within a UL 891 switchboard lineup.

What voltage and current ratings are available?

Low-voltage SBU-AT systems are available for 208V through 600V, 3-phase, 3- or 4-wire systems with current ratings up to 4000A.

Are open and closed transition available?

Yes. SBU-AT systems can be configured for open-transition or closed-transition return operation depending on the application and required transfer sequence.

Can the SBU-AT be service entrance rated?

Yes. Service-entrance configurations are available when required by the application and applicable electrical requirements.

Can monitoring and communications be integrated?

Yes. Metering, source monitoring, automatic transfer controls, communications, and SCADA-ready Modbus connectivity can be incorporated into the system.

Technical Resources

SBU-Series Brochure

View Online

Transfer Controls

View Brochure

Control Spec Sheet

View Online

APTView SCADA

View Online

Ready to Get Started?

Our team can help review your system voltage, current rating, utility and generator sources, transition requirements, service entrance needs, and control requirements.

Contact our sales team to configure an SBU-AT automatic transfer switchboard around your facility and standby power system.

Request a Quote