PHYSICAL FACILITIES
2015 Consultant’s Handbook
Division 33 UTILITIES
7726 MEDIUM VOLTAGE SWITCHGEAR
1
2
2.10
References
Switch & fuse integrated ratings
•
NFPA 70
National Electric Code
Rated Maximum Voltage (KV)
13.8
•
IEEE C2
Code
National Electric Safety
Rated Withstand Impulse BIL
(KV)
95
•
IEEE C37.20.3
Metal-Enclosed
Interrupter Switchgear
Continuous and Load
Interrupting Current (A)
600
•
ANSI C57.12.28 Switchgear
&
Transformer – Pad-Mounted Equipment Enclosure Integrity
Short-Circuit Interrupting Current
(kA rms Sym)
34.6
Duty-Cycle Fault-Close Current
(kA Asym)
40
Load Interrupter Switchgear
2.1 The quality of components is to be that
represented by S & C Electric Co.
2.2 Provide an Incoming Termination section
with surge protection and copper bus connection.
2.3 Provide a switch and fuse combination
section for each transformer, flange connected to
the transformer, with a transition section if
necessary.
2.4 Load interrupter switch shall be a threepole, single-throw, metal-enclosed type with
manual stored energy operator which shall
simultaneously disconnect or connect ungrounded
conductors. The moveable blade of the switch
shall be de-energized when in the open position.
The mechanism shall enable the switch to close
against a fault equal to the momentary rating of the
switch without affecting its continuous current
carrying or load interrupting ability.
3
Pad Mounted, Metal-Enclosed Switchgear
3.1 The quality of components is to be that
represented by:
3.1.1
“PMU Pad-Mounted Switchgear”
per specification 662-451 as modified for PMU
features as manufactured by the S & C Electric Co.
3.2 The
basic
configuration
for
transformer is PMU-5 and for two is PMU-7.
one
3.3 The switchgear shall be configured with
one incoming compartment for radial-feed,
equipped with air-insulated, load-interrupter switch.
The outgoing compartment shall be provided with
fused disconnects.
3.3 Switches shall be provided with a manual,
handle-type operator utilizing a stored-energy
(spring-driven) mechanism to simultaneously open
or close all phases.
2.5 A ground bus shall extend the width of the
switch enclosure and shall be bolted directly
thereto. Connect frame of unit to ground bus and
provide for attachment to ground grid at each end.
3.4 The switchgear shall be configured so that
the switch actuator is padlockable, but may be
accessed without opening the switch compartment
doors.
2.6 The door shall have an inspection window
to allow full view of the position of the three switch
blades.
3.5 Fused compartments shall be disconnect
non-load break type hook-stick removable.
2.7 Switch shall have provision for padlocking
in the open and closed positions.
2.8 Switch shall be fused, with fuses mounted
on a single frame below switch.
2.9 Fuse rating shall be appropriate to provide
125 percent of the transformer full-load rating,
sustain no damage from magnetizing in-rush
current, and provide protection against thermal
damage.
3.6 Switchgear enclosures shall be of
freestanding, self-supporting construction provided
with
separate
incoming
and
outgoing
compartments configured for bottom cable entry.
Enclosures shall be of live-front construction,
provided with a hinged door for access to each
compartment.
Page 1 of 2
PHYSICAL FACILITIES
2015 Consultant’s Handbook
Division 33 UTILITIES
7726 MEDIUM VOLTAGE SWITCHGEAR
3.7 Switch & Fuse Integrated Ratings
Rated Maximum Voltage (KV)
13.8
Rated Withstand Impulse BIL
(KV)
95
Continuous and Load Interrupting
Current (A)
600
Short-Circuit Interrupting Current
(kA rms Sym)
25
Duty-Cycle Fault-Close Current
(kA Asym)
40
Page 2 of 2