Siemens first NXAIR-P arc-vented switchgear goes into service

17 July 2002 – Siemens Power Transmission & Distribution, Inc., announced Monday that its first lineup of the NXAIR-P medium voltage switchgear has been energized and put into service in Watertown, South Dakota.

Produced in the Raleigh, NC switchgear manufacturing facility, this arc-vented lineup applies the latest technologies available for safety, space savings and ease of operation.

“This equipment was part of a major upgrade to our system and we felt that it was the right choice to use the most current technology,” said Rick Berg, electric superintendent for the City of Watertown. “The arc vented feature is a great benefit to our operators.”

The NXAIR-P one-high design enables venting of gases created due to heat build-up during an internal arcing-fault event. Pressure from the expanding gases is directed up and away from the operator. It is expected that arc-venting will become commonly specified in North America due to the recent emphasis on operator safety reflected in the new IEEE C37.20.7 standard for the ANSI market.

“The benefits of arc vented equipment to the operator are clear,” concurred
James Tran, PE of HDR Engineering, Inc., provider of engineering input to the City of Watertown. “Siemens’ 25 years of experience in this area convinced us that the NXAIR-P was the best solution for our customer.”

Besides enabling arc-venting and providing significant space savings, the one-high design of the NXAIR-P makes it easier for an operator to insert and operate a breaker. No lifting device is required and confusion about upper or lower primary cabling identification is eliminated.

“The equipment arrived in a timely manner and throughout the installation Siemens supported our efforts to provide our customer a quality facility. The City is pleased and we are pleased with this installation,” according to Eric Netter, VP and construction manager for Electrical Builders, Inc., Kimball, Minnesota, general contractor of the substation construction project for the City of Watertown.

The modular design of the NXAIR-P simplifies configuring, delivery and operator training. A single-unit section of this innovative switchgear consists of four compartments:

* Circuit-breaker compartment
* Low-voltage compartment
* Main-bus compartment, and
* Cable connection compartment.

“This milestone represents the culmination of a seven-year long process in R&D, engineering, customer focus groups and manufacturing re-design”, said David Lin, product manager for Siemens Medium Voltage Apparatus Division. “We were confident from the start that customers would be drawn to the NXAIR’s smaller footprint, globally compliant engineering and arc-vented safety features.”

The new Siemens NXAIR-P arc-vented switchgear incorporates a unique pressure relief channel and diffuser designed to increase operator safety. The NXAIR-P design has been tested to meet the Type 2 requirements of the new ANSI/IEEE C37.20.7 test guide “Guide For Testing Medium Voltage Metal-Enclosed Switchgear for Internal Arcing Faults.” The NXAIR-P has interrupting ratings of 250MVA – 1000MVA and 25kA – 50kA, voltage classes of 5kV and 15kV, and a continuous current of 1200A – 4000A. The switchgear is air insulated with vacuum interrupter circuit breaker technology.

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