Static Transfer Switch offers true internal redundancy.

Press Release Summary:

Model STS 2 delivers UPS connectivity for applications that require less than 1/4 cycle transfer between sources. It features front access design and operator interface with color touchscreen display. Three separate logic modules with dual input power are each capable of working independently if one or more modules malfunction. LCD monitor offers system mimic diagram, status/alarm panel, and operator instructions and menus.

Original Press Release:

Liebert Introduces New Static Transfer Switch for UPS Connectivity In Mission Critical Applications

STS 2 Features Convenient Front-Access and True Internal Redundancy

ORLANDO, December 10, 2002 - Liebert Corporation ( today introduced the STS 2, a new static transfer switch (STS) that delivers highly reliable, space-saving connectivity for applications that require less than one quarter cycle transfers between sources such as dual uninterruptible power supplies (UPS), UPS and utility or UPS and distributed generation sources such as gensets, microturbines, and fuel cells. Building on the success of the popular Liebert STS, the STS 2 provides greater internal redundancy, more flexibility in installation, easier maintenance and improved operation.

The 100 percent rated STS 2 now features a front access design, triple-redundant logic, separated redundant power supplies, and a redesigned operator interface with a color Touch Screen display.

"The STS 2 represents the best in dual-bus power system technology with Liebert reliability and support," said Bill Barcus, product manager, Liebert Corporation. "It is a key component in dual-UPS systems and delivers the reliability and design flexibility required by applications that have zero tolerance for downtime."

Front Access Design

The front access design of the STS 2 simplifies maintenance and reduces the unit's footprint for added flexibility in system design. It enables the STS 2 to be placed adjacent to or in back of other data center equipment, saving as much as 22 feet of valuable floor space.

All mechanical and electrical components are accessible from the front of the unit, with ample space for cable connections through top and bottom access plates for easier installation. All power train components can be removed and serviced from the front without shutting down the connected load.

True Internal Redundancy

The STS 2 features three physically separate logic modules with dual-input power, each capable of working independently if one or more modules malfunction. A polling scheme ensures the legitimacy of the module output. The unit's dual power supplies feature dual-bus power distribution with dual inputs and independent leads to each module. All power connections have diode protection to prevent propagation of internal or external faults. Internal components are protected by a rugged, fault-resilient package optimized for real-world applications.

Ease of Use

The controls of the STS 2 have been enhanced to improve operator effectiveness, reduce training time and minimize error. The color LCD monitor includes a system mimic diagram, a status/alarm panel, and operator instructions and menus. The mimic diagram delivers a snapshot of system status that allows operators to quickly check operation, while pop-up menus provide detailed operator and diagnostic information.

"Many of the features of the STS 2 are a direct result of our discussions with data center facility managers," said Barcus. "Improving the accessibility and the ease-of-use of this critical switch allows our customers to protect high-availability data systems more simply and effectively."

About Liebert Corporation

Liebert Corporation is a division of Emerson Network Power, an Emerson business which provides a full spectrum of reliable power solutions, including inbound power, connectivity, power supplies, power systems and precision cooling, backed by the largest global services organization in the power industry. These Emerson companies serve the needs of telecommunications networks, data centers, health care and industrial facilities worldwide. For more information, visit

About Emerson

St. Louis-based Emerson ( is a global leader in bringing technology and engineering together to provide innovative solutions to customers in electronics and telecommunications; process control; industrial automation; heating, ventilating and air conditioning; and appliance and tools. Sales in fiscal 2002 were $13.8 billion.

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