SECTION 16342 - METAL CLAD SWITCHGEAR
CONSTRUCTION STANDARD
PART 1: GENERAL
This section of the design standard includes basic requirements for the design of the
metal clad switchgear used at the building service entrances. All breakers designed and
specified shall use vacuum interrupting technology. This design guideline is to be used
in conjunction with Section 16271 – Pad Mounted Transformers and Section 16362 –
Service Entrance Equipment to comprise the service entrance double-ended substation.
This is a design standard and is not intended to be used as a guideline or construction
specification.
PART 2: PRODUCTS
A.
Design and construct the switchgear in accordance with the latest referenced
specifications including NEMA, ANSI, and IEEE standards applicable to
switchgear.
B.
All switchgear parts shall be new and free from defects in material and
workmanship.
C.
The switchgear shall be rated 13,800 volts, metal clad, and shall operate on a
12,000-volt nominal, three phase, solidly grounded wye, 60 Hz system. The
switchgear shall utilize vacuum breaker technology with a line-up including (2)
incoming breakers used as load interrupter switches and (2) breakers used as
transformer feeder circuits.
D.
Enclosure: The switchgear assembly shall consist of individual vertical sections
housing various combinations of circuit breakers and auxiliaries, bolted together to
form a rigid metal-clad lineup. Each vertical section shall have the capability of
stacking breakers two high and auxiliaries four high.
E.
Main Bus: The main bus shall extend the entire length of the line-up and shall be
rated not less than 1200 amp at 12 kV. The bus shall consist of rigidly supported
silver-plated copper bars, braced to withstand not less than 1000 MVA
symmetrical interrupting duty and a minimum momentary rating of 58 kA at 12
kV. The bus bars shall be of suitable design and cross sectional area to
satisfactorily carry the rated current without exceeding the temperature rise as
specified in the IEEE and NEMA standards.
F.
Ground Bus: The ground bus shall be of high conductivity copper with a
continuous rating of at least 600 amps and shall extend the entire length of the
switchgear.
G.
Circuit Breakers:
1. All circuit breakers shall be vacuum type and have the following ratings:
a. Interrupting Rating:
b. Nominal Voltage:
c. Continuous Current:
d. Maximum symm. I.C:
e. Close and latching:
f. Rated interrupting time:
g. Impulse Level:
h. Close Voltage:
1000 MVA
13.8 kV
1200A or as required by design
37 kA RMS @ max. kV
77 kA RMS
5 cycles
95 kV
230 VAC
Design & Construction Standards, Revised December, 2000
16342-1
SECTION 16342 - METAL CLAD SWITCHGEAR
CONSTRUCTION STANDARD
i. Trip Voltage:
AC powered capacitor trip
2. The vacuum breakers used as load interrupter switches shall operate on an
open loop radial feed system. These breakers shall be used for switching
purposes only and shall not require protective type sensing and circuitry.
3. Acceptable breaker element manufacturer’s:
a.
b.
c.
d.
e.
H
Cutler Hammer
General Electric
Powell
Square D
Siemens Energy
Protective Relays:
1. Protective Relays shall be 100% solid state except for the tripping contacts.
Electromechanical relays will provide the tripping contacts. These relays shall
incorporate three phase (50/51) plus neutral protection (51N) in a single
device. The neutral relay functions shall be capable of being turned off. The
device shall have a minimum selection of protective time-current curves that
shall include a standard relay normal, moderate, very, and extremely inverse
designation. The relay shall be powered from the breakers’ 120 VAC source.
2. Protective relay acceptable manufacturers:
a.
b.
c.
d.
I.
Basler BE1-51 Series
MultiLin SR735 Series
Schweitzer SEL-501 Series
General Electric MDP Series
Metering:
1. Coordinate location of metering requirements with University of Texas staff.
If metering at the metal clad switchgear is required, the design shall adhere to
the following:
2. Metering circuits shall be designed such that they may be tested and calibrated
without applying test currents and voltages to any other devices. Position
KWH meters such that the display registers are eye-level. Must be Transdata
Type Mark V meter.
3. The design shall include metering for the following quantities:
a.
b.
c.
d.
e.
f.
g.
KWH Forward
KWH Reverse
KVARH Forward
KVARH Reverse
KQH Reverse
KVAH Forward
KVAH Reverse
4. Available data displays will include the following for each metered quantity:
Design & Construction Standards, Revised December, 2000
16342-2
SECTION 16342 - METAL CLAD SWITCHGEAR
CONSTRUCTION STANDARD
a.
b.
c.
d.
e.
f.
g.
Total Consumption
Maximum Demand
Time of Maximum Demand
Date of Maximum Demand
Current Demand
Previous Demand
Cumulative Demand
5. Available instantaneous displays will include the following:
a.
b.
c.
d.
e.
f.
Watts – Three-Phase
VARS – Three- Phase
Volts – Per Phase
Amps – Per Phase
Time
Day of Week
PART 3: DESIGN/DRAWING REQUIREMENTS
A.
Electrical Engineer shall provide single-line diagram showing gear with draw-out
type breakers.
B.
Floor plans details shall be provided with electric equipment room layouts
including switchgear and other substation components drawn to scale.
C.
Switchgear shall be placed on a 4” housekeeping pad.
D.
Single line diagram shall clearly indicate dividing lines of points of acquisition and
installation responsibility. For example, University of Texas typically provides the
12 kV cable and pad mounted transformers. This should be clearly shown on the
single line diagram.
END OF STANDARD 16342
Design & Construction Standards, Revised December, 2000
16342-3