Medium Voltage Equipment
Medium Voltage Equipment
5-15 kV GM-SG and 38 kV GM38 Metal-Clad Switchgear General
Overview Features Tested to ANSI Standards
Siemens switchgear is tested to meet
Siemens 5, 7, 15 and 38kV class medium Floor Rollout the requirements of ANSI standards. A
voltage, one- or two-high vacuum circuit Circuit breakers in the lower cell can be complete design test program including
breaker switchgear is of the metal-clad rolled out directly on the floor in front of short circuit interruption, load current
type as covered by ANSI standard the unit, without a handling device, lift switching, continuous current,
C37.20.2. All parts are completely truck, or hoist for indoor and Shelter-Clad mechanical endurance, close and latch
enclosed within grounded metal barriers. (walk-in) outdoor installations. A lift truck current, short time and momentary
Circuit breakers are the horizontal accessory is optionally available for withstand, impulse withstand, and the
drawout type. Secondary control devices handling circuit breakers in the upper cell other tests required by the standards has
and primary circuits are isolated from of the 5-15kV GM-SG switchgear, or in been successfully completed. Certified
each other by shutters or barriers. non-walk-in outdoor enclosures, or for test data can be furnished to customers
Primary circuits of different potential are installations of switchgear on a raised upon request. These tests encompass
also separated by barriers. All primary “housekeeping” pad.
the complete equipment design,
bus work and joints are completely Closed Door Racking including both the switchgear structure
encased with insulation material to suit The cell mounted racking mechanism and the circuit breaker removable
the voltage class of the equipment. may be operated with the cell door open element.
Each vertical section may contain a main or closed, through a small opening in the 4000A Rating (5–15kV)
bus bar section and two compartments lower section of each door. For racking, a Designs are available to 3000A self-
for auxiliary devices and / or circuit manual drive crank or an optional electric cooled, and 4000A fan cooled.
breakers, with primary and secondary motor drive may be used.
disconnects, instrument transformers, 3000A Rating (38kV)
Automatic Shutters Designs are available to 2000A self-
instruments and relays, secondary wiring Automatically operated grounded steel
and other necessary components. The cooled and 3000A fan cooled.
shutters are included to allow or block
switchgear is designed so that additional access to the stationary primary UL listing
vertical sections with circuit breakers disconnects. The shutters are designed UL listings to ANSI C37.54/C37.55
and / or auxiliary compartments may be to remain closed until they are forced standards is optionally available.
added in the future. open by insertion of the circuit breaker. cUL Available
The space saving potential of the 5-15kV This design maximizes protection for 50kA Interrupting Rating Available at
type GM-SG cubicle and GMSG circuit maintenance personnel, as compared to up to 15kV
breaker designs allows up to two racking mechanism operated shutters,
drawout elements to be furnished in a which could be opened with the circuit Siemens Relays, see Relaying section
single vertical section. The units can be breaker out of the cell thereby exposing on page 13-25
furnished with two 2000 ampere circuit personnel to energized components.
breakers in one unit. For 3000 ampere White Interior Device Panels in Front
self-cooled or 4000 ampere fan-cooled Compartments Standard
circuit breakers, one rollout auxiliary can
be located in the lower cell, with the 5 through 15kV Available in Two-
circuit breaker in the upper cell; or the High Design
cell can be left blank, with the circuit 38kV Available in One-High Design
breaker located in the lower cell. Only
For more information, please visit http://automation.usa.siemens.com/consultant/ or contact your local sales office.
13-2 Siemens Power Distribution & Control, SPEEDFAX™ 2007-2008 Product Catalog
Medium Voltage Equipment
GM-SG Overview General
Siemens GM-SG 5kV, 7.2kV and 15kV metal-clad power Maintenance Intervals
switchgear assemblies with horizontal drawout type GMSG If applied under ANSl “usual service” conditions, maintenance
vacuum circuit breakers take advantage of the latest of the circuit breaker mechanism is only needed at ten year
developments in vacuum interrupter technology. Up to two intervals.
circuit breakers can be stacked in a single vertical section, Maintenance of the switchgear cubicle is recommended at five
allowing significant space savings. year intervals, and primarily consists of cleaning insulation.
The equipment meets or exceeds the latest standards of ANSI, Floor Rollout
IEEE, and NEMA. No lift truck or dolly is needed to insert or remove circuit breakers
GM-SG switchgear is designed for use in industrial plants, in the lower cell of switchgear located at floor level. For indoor
commercial buildings, electric utility systems, cogeneration switchgear located on a raised “housekeeping” pad or for
installations, and other electrical systems. It is commonly outdoor non-walk-in switchgear, a lift truck is required to handle
used for protection and switching of transformers, motors, circuit breakers.
generators, capacitors, buses, distribution feeder lines, and, in
"Universal" Spare Breaker (up to 50kA)
general, for protection of any medium voltage power circuit. The physical configuration and interlock logic allow the use of a
Siemens experience gained in over 80 years of supplying metal- single circuit breaker to serve as a “universal” spare breaker at
clad switchgear in the U.S. has been captured in the GM-SG an installation site for up to 50kA. The interlock logic checks the
design. The objective has been to incorporate features designed principal rating characteristics (continuous current, maximum
to provide safety, while simplifying operation, maintenance, and voltage, and interrupting current), and allows a circuit breaker to
minimizing installation cost. be inserted in any circuit breaker cell, provided that the circuit
The switchgear structure and the drawout vacuum circuit breaker equals or exceeds the ratings required by the cell.
breaker are an integrated design, with dielectric, thermal, and Single Source Responsibility
interruption integrity built directly into the basic design, not Single source responsibility is assured since the complete
added as an afterthought. equipment is designed by Siemens and is manufactured and
Siemens 3AH3 Operating Mechanism tested in a single facility. The vacuum circuit breakers are
The GMSG circuit breaker uses the proven Siemens 3AH3 checked in the switchgear cells as part of production testing,
stored-energy operating mechanism. This operator is an and shipped in the switchgear to assure interchangeability
evolution of the 3A family of operators first introduced in 1976. and reduce the possibility of damage to circuit breakers in
Over 60,000 3AH3 operating mechanisms have been produced shipment.
since 1998. Full ANSI Design Background
Faster Interruption Full design integrity is assured. ANSl C37.09 and C37.20.2
Standard interrupting time is 5-cycles with an option available require design tests on circuit breakers and structures together.
for 3-cycle interrupting time. The 3AH3 operator is produced in our global center of
competence for circuit breakers in Berlin, and final assembly
Siemens Vacuum Interrupters of both the drawout GMSG circuit breaker and the switchgear
The vacuum interrupters used in the GMSG circuit breaker are structures occurs in a single facility. Siemens controls the
manufactured by Siemens and have been proven in thousands entire process, from design concept to production. Records
of installations since 1976. The chrome-copper contact design are maintained to document compliance with ANSl standards.
used in these interrupters assures low chopping levels,
eliminating the need for surge protection on most circuits. UL or C-UL Listing Available
Where the arrangement of components allows, UL or C-UL
Front Mounted Operating Mechanism Listing is available.
The simple GMSG operating mechanism makes maintenance
and inspection easy. The mechanism is located on the front of Quality Systems
the circuit breaker, rather than underneath. Facilities involved with application, engineering, design and
production are certified to ISO 9001 requirements.
Siemens Power Distribution & Control, SPEEDFAX™ 2007-2008 Product Catalog 13-3
Medium Voltage Equipment
GM-SG Overview General
Figure 1: GM-SG Switchgear 1200A or 2000A a central secondary device compartment, located between
Circuit Breaker Section two cells for auxiliary devices and / or circuit breakers,
including primary and secondary disconnects, instrument
F transformers, instruments and relays, secondary wiring, and
other components as necessary. The switchgear is normally
designed so that additional vertical sections may be added in
B G the future.
The GM-SG design includes full ANSI/IEEE C37.20.2 Metal-
Clad construction. This means complete enclosure of all live
parts and separation of major portions of the circuit to retard
the spread of faults to other compartments. Removable plates
I permit access to all compartments. The rear panels are
D individually removable to allow separate access either to
J downfeed or upfeed cable connections.
A K The structure is constructed of bolted steel for better
dimensional control than with welded designs. Sheet steel
interunit barriers extend the full height and depth of each
H vertical section for isolating adjacent sections. The ground bus
extends the entire length of the complete switchgear lineup,
A. Current transformers F. Outgoing cable lugs
and to all circuit breaker cells.
2 per bushing (downfeed shown) Circuit Breaker Interchangeability
standard accuracy G. Surge arresters The GM-SG switchgear cubicle and the removable GMSG
B. Upper circuit breaker H. Ground sensor CT circuit breaker element are both built to master fixtures so
C. Isolated relay and I. Main bus bars circuit breakers of the same ratings are interchangeable with
instrument compartment J. Removable barrier
each other even if the circuit breaker is required for use with a
D. Inter-unit wiring K. Power cable duct
E. Lower circuit breaker
cell with "provisions only" supplied years earlier. The GMSG
circuit breaker is not interchangeable with the older designs.
Structural Flexibility A circuit breaker of higher rating (up to 50kA) can be used in a
Siemens GM-SG metal-clad switchgear provides enhanced cell of equal or lower rating, i.e., a 3000A 50kA 15kV circuit
flexibility in locating circuit breaker, auxiliary, and metering cells breaker can be used in a 1200A 25kA 15kV circuit breaker cell.
within the structure layout. Circuit breakers rated 1200A and Tested to ANSl/IEEE Standards
2000A may be located in upper or lower cell positions. Siemens GM-SG switchgear is tested to meet the
Bus sectionalizing (tie) circuit breaker cells may be located on requirements of ANSl/IEEE standards. A complete design test
the upper or lower levels and are ordinarily located next to an program, including short circuit interruption, load current
auxiliary cell on the same level to accommodate transition bus switching, continuous current, mechanical endurance, close
work. and latch current, short time and momentary withstand,
impulse withstand, and the other tests required by the
3000A circuit breakers can be located either in the bottom cell standards has been successfully completed. These tests
or the top cell of a vertical section. If the 3000A circuit breaker encompass the complete equipment design, including both
is located in the lower cell, the upper cell can be used for the switchgear structure and the circuit breaker removable
metering devices only. If the 3000A circuit breaker is in the element. Production tests in accordance with ANSl/IEEE
upper cell, the lower cell may be used to house a set of standards are performed on every group of switchgear and on
drawout voltage transformers, or a drawout control power each circuit breaker. Certified copies of all test data can be
transformer, or rollout fuses for a remote control power furnished to customers upon request.
The switchgear is not classified as arc-resistant switchgear,
The 3000A circuit breaker can be used for 4000A continuous and has not been tested for resistance to internal arcing per
current applications, with the addition of fan cooling IEEE C37.20.7. Qualification to seismic requirements of
equipment in the auxiliary cell above or below the circuit various codes (e.g., IBC-2006, UBC, IEEE 693, etc.) is
breaker. This application of fan cooling is well suited if loads available. Consult Siemens with detailed requirements.
above 3000A are infrequent, as for example, in the case of a
fan-cooled rating on a power transformer. UL or C-UL Listing Available
When specified, if the component configuration allows, the
Each vertical section contains the main bus bar compartment switchgear can be provided with the UL or C-UL (for use in
plus a rear compartment for incoming and outgoing Canada) listed label, indicating conformance to the
connections. The front portion of the vertical section contains requirements of ANSl C37.54 and ANSI C37.55.
13-4 Siemens Power Distribution & Control, SPEEDFAX™ 2007-2008 Product Catalog
Medium Voltage Equipment
GM-SG Vacuum Circuit Breakers General
Type GMSG Vacuum Circuit Breakers Floor Rollout
5kV, 7.2kV and 15kV When located in the lower cell, the circuit breakers are
arranged to rollout directly on the floor in front of the
Siemens Type GMSG circuit breakers are available in 25kA
switchgear if the switchgear is not located on a
through 63kA* interrupting classes, or 250MVA through
“housekeeping” pad. No adapter, hoist, or lift truck is
1000MVA on the older “constant MVA” rating basis.
Continuous current ratings include 1200A, 2000A, and 3000A
self-cooled. 4000A is available using a 3000A circuit breaker Mechanism Operation
together with forced-air (fan) cooling in the switchgear cubicle. The mechanism is arranged to pre-store closing energy in the
closing springs. The closing springs are selected so that they
*Consult factory for availability of 63kA
provide sufficient energy not only to close the circuit breaker
Maintenance Features safely into maximum "close and latch" currents, but also to
The GMSG circuit breakers incorporate many features pre-store the tripping energy necessary to open the circuit
designed to reduce and simplify maintenance, including: breaker. The closing springs can be manually charged during
▪ Virtually maintenance-free vacuum interrupter maintenance or in emergency conditions, but are normally
charged electrically automatically after each closing operation.
▪ Ten year maintenance interval
▪ Floor rollout Interlocks
The racking system prevents racking of a closed circuit
▪ Front mounted operator breaker, and keeps the circuit breaker trip-free during racking.
▪ Common operator family The racking mechanism can be padlocked to prevent
▪ Simple outer-phase barriers unauthorized operation. Padlocks can also be applied to the
▪ “Universal” spare circuit breaker concept racking mechanism to maintain the circuit breaker in the trip-
▪ Non-sliding current transfer
▪ Rugged secondary disconnects Stored Energy Operator
The GMSG circuit breaker utilizes the Siemens 3AH3 stored
Ten Year Maintenance Interval on GMSG Circuit Breaker
energy operator for long life, high reliability, and ease of
When applied under mild conditions (ANSI “usual service”
maintenance. Parts used in the manufacture of the circuit
conditions), maintenance is only needed at ten year intervals
breaker are precision tooled or produced on numerically
on the circuit breaker. The maintenance interval for the
controlled equipment. The circuit breaker design includes
switchgear cubicles is five years.
frequent use of inherent alignment techniques.
Low Maintenance Requirements
The interrupter is a sealed unit, so the only maintenance
necessary is to clean off any contaminants and to check the
vacuum integrity. The vacuum interrupters can be
disconnected from the stored energy mechanism quickly,
without tools, and vacuum integrity inspected by hand;
alternatively, a simple hi-pot test can be used.
Front Side (barriers removed) Rear
Figure 2: GMSG Circuit Breaker
Siemens Power Distribution & Control, SPEEDFAX™ 2007-2008 Product Catalog 13-5
Medium Voltage Equipment
GM-SG Ratings Selection
Table 1: Type GMSG Circuit Breaker Ratings (New “Constant kA” Ratings Basis)
These ratings are in accordance with the following standards:
▪ ANSI/IEEE C37.04-1999 Standard Rating Structure for AC High-Voltage Circuit Breakers
▪ ANSI C37.06-2000 AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis - Preferred Ratings and Related
▪ ANSI/IEEE C37.09-1999 Standard Test Procedure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis
▪ ANSI/IEEE C37.010-1999 Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis
Circuit Breaker Type
Rated Values Units 5-GMSG- 5-GMSG- 5-GMSG- 7-GMSG- 15-GMSG- 15-GMSG- 15-GMSG- 15-GMSG-
40 50 63 40 25 40 50 63
xxxx-104 xxxx-130 xxxx-164 xxxx-104 xxxx-65 xxxx-104 xxxx-130 xxxx-164
Maximum Design Voltage (V) kV rms 4.76 4.76 4.76 8.25 15.0 15.0 15.0 15.0
Voltage Range Factor (K) — 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
kV rms 19 19 19 36 36 36 36 36
Voltage Levels Lightning
kV crest 60 60 60 95 95 95 95 95
1200 1200 1200 1200 1200 1200 1200
2000 2000 2000 2000 1200 2000 2000 2000
Continuous A rms
3000 3000 3000 3000 2000 3000 3000 3000
4000FC 4000FC 4000FC 4000FC 4000FC 4000FC 4000FC
Short-Circuit (I) kA rms sym 40 50 63 40 25 40 50 63
ms 83 83 83 83 83 83 83 83
Interrupting Time cycles 5 5 5 5 5 5 5 5
Permissible Tripping Delay (Y) Sec 2 2 2 2 2 2 2 2
Max. Sym. Interrupting (I) kA rms sym 40 50 63 40 25 40 50 63
% dc Component % 47 47 47 47 47 47 47 47
Short-Time Current (I)
kA rms 40 50 63 40 25 40 50 63
Closing & Latching
(Momentary) Asymmetrical kA rms 62 78 98 62 39 62 78 98
(1.55 x I)
Closing & Latching
kA peak 104 130 164 104 65 104 130 164
(2.6 x I)
“xxxx” in type designation refers to the continuous current rating 1200, 2000, or 4000FC indicates that fan cooling is included in the switchgear structure for this
3000A, as appropriate. The 4000A fan-cooled rating is achieved using a 3000A rating. 4000A rating is not available in outdoor equipment.
circuit breaker, in combination with fan cooling as indicated in footnote 4. All values apply to polyphase and line-to-line faults.
Maximum design voltage for which the circuit breaker is designed, and the upper Standard duty cycle is O - 0.3s - CO - 3 min. - CO.
limit for operation. Standard rated interrupting time is 5 cycles (83ms). Optional rated interrupting time
K is listed for informational purposes only. For circuit breakers rated on a “constant of 3 cycles (50ms) is available.
kA basis”, the voltage range factor is 1.0. Consult factory for availability.
13-6 Siemens Power Distribution & Control, SPEEDFAX™ 2007-2008 Product Catalog
Medium Voltage Equipment
GM-SG Ratings Selection
Table 2: Type GMSG Circuit Breaker Control Data
Control Voltages, ANSI C37.06 Spring Charging Motor
Close Coil Trip Coil
Range Amperes Charging
Close Trip Amperes Amperes Run (Avg.) Seconds
24 VDC 19 - 28 14 - 28 5.8 17 / — — —
48 VDC 36 - 56 28 - 56 2.9 11.4 / 30 8 10
125 VDC 100 - 140 70 - 140 1.0 4.8 / 7.4 4 10
250 VDC 200 - 280 140 - 280 0.5 2.1 / 4.2 2 10
120 VAC 104 - 127 104 - 127 0.9 — 6 10
240 VAC 208 - 254 208 - 254 0.4 — 3 10
Current at nominal voltage.
Capacitor trip. Table 5: Current Transformers
Value preceding slash ( / ) is the current for the standard trip coil with standard
rating interrupting time. Value following ( / ) is current for optional trip coil 60Hz Metering Accuracy at Burden Relay
with 3-cycle interrupting time. Ratio
— means this selection not available in this voltage. B0.1 B0.5 B1.0 B2.0 Class
Type MD Torroidal Standard Accuracy
100:5 2.4 — — — C 15
150:5 0.6 2.4 — — C 20
Table 3: Interrupting Capacity Auxiliary Switch Contacts
200:5 0.6 1.2 — — C 25
Continuous Control Circuit Voltage
Type 250:5 0.6 1.2 2.4 — C 35
Current 120 240 48 125 250
Switch 300:5 0.6 0.6 1.2 2.4 C 40
Amperes AC AC DC DC DC
400:5 0.3 0.6 1.2 2.4 C 60
10 10 5 10 / 30 5 3
Breaker 500:5 0.3 0.3 0.6 1.2 C 75
600:5 0.3 0.3 0.6 1.2 C100
TOC 15 15 10 0.5 0.5 0.2
800:5 0.3 0.3 0.6 0.6 C130
MOC 20 15 10 10 10 5 1000:5 0.3 0.3 0.3 0.3 C170
1200:5 0.3 0.3 0.3 0.3 C200
2 contacts in series.
All switch contacts are non-convertible. 1500:5 0.3 0.3 0.3 0.3 C200
2000:5 0.3 0.3 0.3 0.3 C210
2500:5 0.3 0.3 0.3 0.3 C300
Table 4: Voltage Transformers
3000:5 0.3 0.3 0.3 0.3 C240
Accuracy Class 4000:5 0.3 0.3 0.3 0.3 C230
at 120V Sec. VA
Ratio Thermal Type MDD Torroidal Special Accuracy
X, Y, Z Z ZZ Rating
75:5 2.4 4.8 — — C 20
100:5 1.2 2.4 — — C 30
5kV 2400 / 120 0.3 1.2 — 500
150:5 0.6 1.2 2.4 4.8 C 40
5kV 4200 / 120 0.3 1.2 — 500 200:5 0.6 1.2 1.2 2.4 C 60
250:5 0.3 0.6 1.2 2.4 C 80
5kV 4800 / 120 0.3 1.2
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