GM38 non-arc-resistant, air-insulated, metal-clad switchgear
Rated short-time withstand current up to 40 kA
Rated continuous current up to 3,000 A*
Lightning impulse (BIL) up to 150 kV
Air-insulated, medium-voltage, non-arc-resistant switchgear
Type GM38 metal-clad air-insulated switchgear can meet almost any switchgear application from 23 kV through 38 kV.
The horizontal drawout vacuum circuit breakers occupy the lower cell with voltage transformers (VTs) or drawout fuses available in the upper cell.
The lower cell may be used for auxiliaries, such as VTs, a control power transformer (CPT) or drawout fuses.
Two types of outdoor housing are offered: non-walk-in and Shelter-Clad.
Siemens Integrated Electric-Racking System (SIERS) is optionally available with type GM38 non-arc-resistant switchgear.
Watch the videos below to learn more about GM38 switchgear, and its Sm@rtGear option.
Air-insulated, medium-voltage, non-arc-resistant switchgear
- One-high construction
- Up to 50 full-fault interruptions
- Universal spare circuit breaker
- Closed door racking
- Interlocks permit insertion of higher rated vacuum circuit breaker into lower rated cell but not vice versa
- Front accessible circuit breaker operating mechanism for ease of maintenance • Floor rollout circuit breaker in lower cell without a dolly
- Visible secondary disconnect
- Pair with Siemens protective relays to match any typical application
- Horizontal drawout type 38-3AH3 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
- 10,000 operations to overhaul
- Three-cycle interrupting time (optional)
- SIERS integrated electrical-racking system available (optional)
- Optional Sm@rtGear™ functionality provides predictive diagnostics, continuous monitoring, and control from a remote location
- Meets or exceeds the latest ANSI, IEEE and NEMA standards
- UL Listing for 40 kA available.
Type GM38 switchgear available as:
- Indoor (type GM38)
- Outdoor, walk-in, Shelter-Clad NEMA 3R (type SGM38) single aisle or common aisle
- Outdoor, aisleless non-walk-in (type OGM38).
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 GM38 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 38-3AH3 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 GM38 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).
Type 38-3AH3 circuit breaker ratings constant kA basis - ANSI/IEEE C37.06-2009
1 3,000 A circuit breaker together with a modified switchgear structure incorporating fan-cooling equipment. 3,000 A is not available in outdoor equipment.
1 Add 6“ (152 mm) to each end of lineup for aisle extension 12” (305 mm) total.
2 Add for roof and enclosure overhang:
Rear (cable side):
- Non-walk-in: 3.9” (98 mm)
- Shelter-Clad 3.9” (98 mm).
Front (drawout side):
- Non-walk-in: 6.9” (175 mm)
- Shelter-Clad 1.5” (38 mm).
3 If indoor switchgear is installed on a raised housekeeping pad, the pad must not extend further than 3“ (75 mm) from the front of the switchgear to avoid interference with the use of the portable lift truck.
4 96.0” (2,438 mm) aisle space recommended and allows room for interchange of circuit breakers. Minimum aisle space required for handling circuit breakers with lift truck is 80” (2,030 mm)
TechTopics is a series of papers that discuss issues of interest to users or specifiers of electrical equipment.
- 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. 06 - Three-cycle versus five-cycle interrupting time
- No. 07 - Current transformers - Use of 600 V CTs in metal-clad switchgear
- No. 09 - Heat generation estimation for type GM38 switchgear (up to 38 kV)
- 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. 43 - Interposing relay requirements
- No. 44 - Anatomy of a short circuit
- 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. 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. 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