GM-SG non-arc-resistant, air-insulated, metal-clad switchgear
Rated short-time withstand current up to 63 kA
Rated continuous current up to 4,000 A to 17.5 kV and 3,000 A 27 kV
Lightning impulse (BIL) up to 125 kV
Air-insulated, medium-voltage, non-arc-resistant switchgear
Siemens type GM-SG 5 kV, 7.2 kV, 15 kV, 17.5 kV, and 27 kV metal-clad power switchgear assemblies with horizontal drawout type GMSG vacuum circuit breakers take advantage of the latest developments in vacuum interrupter technology. Up to two circuit breakers can be stacked in a single vertical section, allowing significant space savings.
The equipment meets or exceeds the latest standards of ANSI, IEEE and NEMA.
Type GM-SG switchgear is designed for use in industrial plants, commercial buildings, electric utility systems, cogeneration installations and other electrical systems. It is commonly used for protection and switching of transformers, motors, generators, capacitors, buses, distribution feeder lines and, in general, for protection of any medium-voltage power circuit.
Siemens experience gained in over 80 years of supplying metal-clad switchgear in the U.S. has been captured in the type GM-SG design. The objective has been to incorporate features designed to provide safety, while simplifying operation, maintenance and minimizing installation cost.
The switchgear structure and the drawout vacuum circuit breaker are an integrated design, with dielectric, thermal and interruption integrity built directly into the basic design, not as an afterthought.
Siemens Integrated Electric-Racking System (SIERS) is optionally available with type GM-SG switchgear.
Watch the videos below to learn more about GM-SG switchgear, its Sm@rtGear option, and Shelter-Clad+ type enclosures.
Air-insulated, medium-voltage, non-arc-resistant switchgear
- One-high or two-high construction
- Up to 100 full-fault interruptions
- Universal spare circuit breaker for 50 kA and lower ratings
- Universal spare circuit breaker for 63 kA ratings
- Interlocks permit insertion of higher rating vacuum circuit breaker into lower rated cell but not vice versa
- Closed door racking
- Front accessible circuit breaker operating mechanism for ease of maintenance
- Floor rollout circuit breaker in lower cell without a dolly
- Visible secondary disconnect
- Circuit breaker ships inside of cell, thus reducing installation cost and transit damage
- Pair with Siemens protective relays to match any typical application
- Horizontal drawout type GMSG vacuum circuit breaker with type 3AH3 operating mechanism
- Uses the latest developments in vacuum interrupter technology
- Highly reliable vacuum interrupters - MTTF over 50,000 years
- Common type 3AH3 operator platform for all ratings
- Over 120,000 type 3AH3 operators produced since 1998
- Generator circuit breakers (to IEEE C37.013 optionally available)
- 10,000 operations to overhaul
- Three-cycle interrupting time (optional)
- Siemens integrated electric-racking system (SIERS) available (option)
- Optional Sm@rtGearTM functionality provides predictive diagnostics, continuous monitoring, and control from a remote location
- Meets or exceeds the latest ANSI, IEEE and NEMA standards
- UL or C-UL Listing available.
Type GM-SG switchgear available as:
- Indoor (type GM-SG)
- Outdoor walk-in Shelter-Clad NEMA 3R (type SGM-SG) single-aisle (factory-assembled aisle) or factory-insulated and assembled aisle (optional)
- Outdoor walk-in Shelter-Clad+ factory-assembled switchgear and aisle on common base with power equipment center type options (type S+GM-SG).
- Outdoor, aisleless non-walk-in (type OGM-SG).
Standard accessories include:
Manual racking crank
Spring charging crank
Drawout extension rails (facilitate handling of circuit breakers in upper cell)
Lifting sling (for circuit breakers above floor level)
Split plug jumper (standard unless test cabinet is furnished)
- Touch-up paint.
Optional accessories include:
Circuit breaker lift device
Test cabinet (in place of split plug jumper)
Test plugs (if required by devices)
Electrical racking motor assembly (to enable racking while operator is at a distance from the switchgear)
- Manual or electrical ground and test device.
Test provisions, either a split plug jumper or a test cabinet, are available for testing the circuit breaker outside its cubicle.
The split plug jumper is used to bridge the secondary disconnects with a flexible cable, so the circuit breaker may be electrically closed and tripped with the control switch on the instrument panel while the circuit breaker is outside of its compartment. The test cabinet, including a control switch, is used for closing and tripping the circuit breaker at a location remote from the switchgear.
Siemens integrated electrical-racking system (SIERS)
Features and benefits
Siemens integrated electric-racking system (SIERS) is an option that is available with Siemens type GM-SG non-arc-resistant, medium-voltage switchgear. It provides additional personnel protection against arc-flash exposure for operators by providing a means of remotely racking the type GMSG drawout circuit breaker. SIERS reduces the need for personal protective equipment (P.P.E.) per the NFPA-70E® standard.
- Maintain all of the safety interlocks as required by IEEE standard C37.20.2
- Logic control module for control and circuit protection
- Interference detection
- Control pendant (hand-held controller)
- High-torque, fixed-mounted dc motor
- Available for 125 V dc external power supply
- Factory installed and tested as a complete racking system.
- Powered from 120 V ac sources in switchgear
- Provision for external power source
- Integrated into the switchgear secondary control circuits or with the protection relay to provide interface with local HMI or SCADA systems
- Field retrofit for existing Siemens type GM-SG non-arc-resistant, medium-voltage switchgear.
Type SIERS device is available in three configurations:
- Basic version
- Local HMI version (Sm@rtGear™ power distribution solution)
- Custom version (i.e., SCADA or other system).
Sm@rtgear technology option
Intelligent devices (circuit breakers, relays, meters, etc.) have existed for more than 30 years. These devices are self-monitoring, configurable, and communicating, but individually they are only islands of intelligence. Historically integrated remote monitoring, configuration, and control have only been available with the inclusion of upstream PMCS, PCS, DCS, or SCADA systems.
With the advent of Siemens Sma@rtGear technology, remote monitoring, configuration, and control are standard features that are integral to the electrical apparatus product.
Advantages at a glance:
- Keeping business operational with maximum uptime
- Reliable energy-efficient products and systems
- Ease of operation and maintenance
- Remote access for arc-flash mitigation
- Integration with existing equipment
- One supplier for all power distribution needs
- Long-term partner over entire lifecycle
- Technology leader with durable solutions
- 24/7 hotline support.
Sm@rtGear features, benefits and details for medium-voltage air-insulated switchgear:
- Types: GMSG vacuum circuit breakers
- Maintenance mode: yes
- Metering: Q200, Q100, P855
- Protective relays: Yes, standard Siemens SIPROTEC
- Remote racking: Yes, optional integrated accessory
- Remote open/close: Yes
- HMI size: 22"
- Auto-throwover: Yes
- Temperature sensing: Yes, optional
- Optional accessories: High-resistance grounding, partial-discharge monitoring.
For more information about the entire Sm@rtGear portfolio for low- and medium-voltage power distribution equipment, please go to Sm@rtGear™ power distribution solution.
- All values apply to polyphase and line-to-line faults.
- Standard duty cycle is O - 0.3 s - CO - 3 min. - CO.
- Fan-cooled rating available using a circuit breaker together with a modified switchegar structure incorporating fan-cooling equipment. Consult factory for rating in Shelter-Clad and Shelter-Clad+ outdoor switchgear. FC rating is not available in OGM-SG non-walk-in. When FC circuit breakers are furnished, main bus is self-cooled.
- Dimensions are approximate.
- Add 6“ (152 mm) to each end of lineup for aisle extension 12“ (304 mm) total.
- 72” (1,829 mm) aisle space recommended allows room for interchange of circuit breakers. Minimum aisle space required for handling circuit breaker with lift truck is 65” (1,651 mm). Minimum aisle space required if all circuit breakers are at floor level is 55” (1,397 mm).
- If indoor switchgear is installed on a raised housekeeping pad, the pad must not extend farther than 3” (75 mm) from the front of the switchgear to avoid interference with the use of the portable lift truck. Add for roof & enclosure overhang: Rear: Non-walk-in: 3.6” (92 mm), Shelter-Clad: 3.6” (92 mm). Front (drawout aisle): Non-walk-in: 3.7” (94 mm), Shelter-Clad: 1.7” (43 mm).
- The switchgear must have at least 6” (152 mm) horizontal clearance.
- Add 4.5” (114 mm) to depth for front and rear doors.
- Add weight of circuit breakers.
- Maximum shipping group five sections.
- Shelter-Clad+ switchgear assemblies (types S+GM-SG) are built in partnership with Siemens-qualified vendors, who provide detailed drawings of each custom assembly, which include dimensions and weights. Please be sure to carefully review and follow all instructions provided in the order-specific Shelter-Clad+ drawing package.
10. For transfer bus arrangements, add 15" (381 mm) to the depth.
TechTopics is a series of papers that discuss issues of interest to users or specifiers of electrical equipment.
- No. 01 - Surge limiter application recommendations for metal-clad switchgear up to 15 kV
- No. 02 - Loss of vacuum
- No. 03 - Vacuum vs. SF6
- No. 04 - kA rated circuit breakers and switchgear
- No. 05 - Reclosing applications - minimum reclosing time
- No. 07 - Current transformers - Use of 600 V CTs in metal-clad switchgear
- No. 14 - X-radiation emissions by vacuum interrupters
- No. 15 - Expected life of electrical equipment
- No. 16 - Bus joint fundamentals
- No. 17 - Main bus continuous current rating
- No. 18 - Bus joint and primary disconnect plating
- No. 19 - Bus joint current density
- No. 21 - “Bus bracing” in metal-clad switchgear
- No. 24 - Checking integrity of vacuum interrupters
- No. 25 - Shunt reactor switching applications
- No. 26 - Ground bus ratings
- No. 27 - Standards for medium-voltage metal-clad switchgear
- No. 29 - Derating factors for reclosing service
- No. 30 - Altitude correction factors
- No. 31 - Solar radiation correction factors
- No. 32 - Capacitor switching applications
- No. 33 - Clearance requirements in switchgear and control equipment
- No. 35 - Transient recovery voltage
- No. 36 - Early “b” contacts
- No. 37 - Low current switching capabilities
- No. 38 - Harmonic filter application
- No. 41 - Circuit breakers or switches - application considerations
- No. 42 - Circuit breakers or vacuum contactors - application considerations
- No. 43 - Interposing relay requirements
- No. 44 - Anatomy of a short circuit
- No. 47 - 7.2 kV equipment basic insulation levels (BIL)
- No. 48 - Fan-cooling control circuit for forced-air cooled circuit breakers
- No. 50 - Ground sensor current transformer cable routing
- No. 52 - Insulation of switchgear terminations
- No. 55 - Capacitor trip devices
- No. 56 - Switchgear outdoor enclosure type - Why isn’t it NEMA 3?
- No. 57 - Arc flash hazard labels
- No. 59 - Control power sources for switchgear
- No. 60 - Use of cable for connections in medium-voltage switchgear
- No. 61 - Circuit breaker “standard duty cycle”
- No. 62 - A bit of history on circuit breaker standards
- No. 65 - Arc-furnace switching applications
- No. 66 - Clearances
- No. 67 - %dc component
- No. 69 - Fast bus transfer times for type GMSG circuit breakers
- No. 71 - Generator circuit breakers
- No. 72 - Generator circuit breaker applications - delayed current zeroes
- No. 73 - Generator circuit breaker applications - transient recovery voltage
- No. 74 - Heat generation estimation for type GM-SG or GM-SGAR switchgear (up to 15 kV)
- No. 75 - Ferroresonance in ungrounded systems with voltage transformers connected line-to-ground
- No. 77 - Residual voltage on load side of an open circuit breaker
- No. 78 - Personal protective equipment (PPE) required with metal-clad switchgear
- No. 79 - Working space required around electrical equipment
- No. 81 - Arc-flash incident energy mitigation
- No. 82 - Continuous current capability in ambient temperatures other than 40 °C
- No. 84 - Space heater - sizing and application principles
- No. 85 - Temperature limitations for user’s power cables
- No. 86 - Use of unshielded cables for connections in medium-voltage switchgear and motor controllers
- No. 87 - Ground and test devices
- No. 88 - Application of maintenance grounds in switchgear
- No. 90 - Temperature ratings for external cables
- No. 91 - Current transformer relaying accuracies - IEEE compared to IEC
- No. 93 - Capacitor switching performance classes
- No. 94 - Circuit breaker interlocking and operating requirements
- No. 95 - Tie circuit breakers and out-of-phase applications
- No. 96 - Phase sequence versus phase arrangement
- No. 98 - Ground protection in metal-clad switchgear - ground sensor current transformers vs. residual connection of current transformers
- No. 100 - Third-party listing - UL, C-UL and CSA
- No. 102 - Tapered bus
- No. 107 - Dummy circuit breaker applications
- No. 110 - Corrosion prevention effects on electrical equipment life
- No. 113 - Preferred locations for current transformers
- No. 115 - Third-party listing/labeling and recognition
- No. 117 - MOC / TOC switches
- No. 118 - Bolted construction vs. welded construction
- No. 119 - Momentary ratings – peak or rms?
- No. 120 - High-potential testing – current doesn’t matter!
- No. 122 - Current transformer thermal-rating factor
- No. 126 - Testing of vacuum interrupters with dc test sets
- No. 129 - Interrupting capacity for system X/R ratios exceeding 17
- Entire TechTopics catalog
Securing project funding
The bipartisan infrastructure law provides the largest long-term investment in U.S. infrastructure in nearly a century. Siemens can help you access and compete for project support.
Improving electrical safety by design
Learn about how our products, solutions, and services can help address various challenges at your facility.