SF6 CIRCUIT BREAKER

DEAD TANK TYPE

MODEL: 300-SFMT-40E300-SFMT-50E

IntroductionMitsubishi Electric Power Products, Inc. is anaffiliate of Mitsubishi Electric Corporation.

Factor yMitsubishi Electric Power ProductsManufacturing facility is located inWarrendale, Pennsylvania, a suburb ofPittsburgh. This location also serves as thecenter for product service and training.

Evolut ionar y DesignThousands of breakers rated at transmissionvoltages through 1100kV have been installedand are operating reliably on T&D systemsworldwide. Introduced in 1974, the design isbased on proven engineering principals andextensive development and testing.

The SFMT features mechanically independentpole-operated, isolated phase dead tankssupported by galvanized steel frames. Each

tank houses a single-break puffer interrupterand supports two porcelain or compositebushings.The tanks and bushings are pressurizedwith SF6 gas.

The frame of each phase also supports themechanism cabinet. It houses a torsionspring-type operating mechanism and interphaselinkages.The control cabinet can be mountedon any phase and houses the control circuits.

TYPE 300-SFMT-40E 300-SFMT-50E

Voltage (max kV) 362 362

BIL (kV Crest) 1300 1300

60 Hz withstand (kV) 555 555

Continuous Current (A) 1200 / 2000 / 3000 1200 / 2000 / 3000

Interrupting Current (kA) 40 50

Interrupting Time (cycles) 2 2

Total Weight (lbs/kgs) 6621 / 3003* 6621 / 3003*

Weight of SF6 (lbs/kgs) 365 / 166 365 / 166

* Per Pole

Revolut ionar y PerformanceThe SFMT breaker reflects MitsubishiElectric's commitment to supply powercircuit breakers with extended service lives,that meet or exceed the most demandingspecifications for interrupting, insulating, andcurrent-carrying capabilities.The design andperformance of all breakers are fully verifiedin accordance with the procedures of ANSIC 37 and IEC 62271-100, and by Mitsubishi'sfactory procedures that subject the breakersto conditions that are considerably morecomprehensive and severe.

These procedures have confirmed the safetyand ruggedness of Mitsubishi breakers. Forexample, tests confirm Mitsubishi breakerswithstand 10,000 mechanical operations andsevere seismic forces, and that they operatereliably in extremely low or high temperatures.

Users also report extraordinarily low costof ownership based on exceptional reliability,application flexibility, safety, and ease ofmaintenance.

Features of the SFMTDesign Insulat ion

• Dead Tank Construction• Only SF6 for Open Gap Insulation• No Solid Insulation Bridging the

Open Contacts• Low Operating Pressure

(85 psig @ 20ºC) for 362kV,40kA and 50kA ratings

Primar y Electr icalParts / Interrupters

• True Puffer Interrupters• Contacts Easily Accessible

for Inspection and Changeout• Verified Full Dielectric and Interrupting

Rating at Lockout Pressure• High Strength Porcelain or

Composite Bushings• Integral NEMA 4-hole bushing terminal

Application Flexibility• Mechanically Tested and Verified

to –50˚C with tank heaters• Definite Purpose Capacitive Current

Switching Capability• Reactor Switching Capability• Tested and Verified for

Seismic Applications• Quiet Operation;

Suitable for Urban Installations

Mechanical Operations• Spring Type Operating Mechanism• Energy Stored in Powerful Torsion Bars• Universal Type Spring Charging Motor

(AC/DC)• Quick Spring Charging for

O-CO-10 sec-CO Duty Cycle

Rapid Instal lat ion• Integral NEMA 4-Hole

Bushing Terminals• Complete Breaker Factory Assembled

and Production Tested

Controls• Space for a maximum of Four

BCTs per Bushing

Proof• Tested and Verified for 90%

Short Line Fault

Fault• Tested and Verified to

Exceed ANSI and IEC Standards• Verified in Environmental Test Lab• Production Tested as a

Fully Assembled Breaker

Options• Tank Heaters for

Low Temperature Applications• High Altitude• Composite Insulators

- Factory Installed Interphase Wiring and "I"- Beam Base

Features to ReduceInstal lat ion andMaintenanceAll SFMT breakers are fully assembled,pressurized and tested to ANSI or IEC andMitsubishi standards prior to shipment.Each breaker is shipped under partialpressure with dry nitrogen gas. Installation iscompleted rapidly and easily with the assistanceof a Mitsubishi field service engineer. Sitework is limited to removing all packing,bolting the frame to the foundation, andinstalling the bushings.Then, the interruptertanks and bushings are vacuum-filled tooperating pressure with bottled SF6 gas, andthe control and power leads are connected.The breaker is then ready for final inspectionand any field testing required by the user.

The torsion bar spring mechanismrequires no maintenance over the lifeof the breaker.

Critical interrupter components (stationaryand moving arcing contacts and nozzles)need only be inspected after 2000 operationsat rated load current. The components areremoved easily by simply unbolting the tankinspection cover. Unlike other designs, thereare no interrupter valves, seal rings,solid insulation or screens to inspect.