Technical data

Instrumentation and protective relays
Instruments, meters and protective relays
can be traditional switchboard type or
modern electronic type, depending on
the requirements of the specification. If
traditional electromechanical devices are
used, they have semi-flush cases with
dull black covers. Indicating and
recording instruments, meters and
protective relays are of the rectangular
type, semi-flush mounted. All scales have
a suitable range and are designed with
black letters on a white background.
Control and instrument switches
Switches furnished are rotary,
switchboard type and have black handles.
Circuit breaker control switches have
pistol-grip handles, while instrument
transfer switches have round notched
handles, and auxiliary or transfer
switches have oval handles.
Circuit breaker control switches have a
mechanical flag indicator showing a red
or green marker to indicate the last
manual operation of the switch.
Outdoor housings
Two types of outdoor housing – non-
walk-in and Shelter-Clad – are available to
meet almost any application. For both
types, the underside of the base is coated
with a coal tar emulsion. The switchgear
is shipped in convenient groups for
erection in the field.
Non-walk-in design
The non-walk-in switchgear consists of
indoor type circuit breaker and auxiliary
cubicles located in a steel housing of
weatherproof construction. Each vertical
section has a full height exterior front
door with provision for padlocking. Each
cell is also equipped with an inner hinged
front door for mounting protective relays,
instrumentation and control switches.
Two removable rear panels are included
for cable access to the primary
termination area. Each cubicle includes
necessary space heaters, a switched lamp
receptacle for proper illumination of the
cubicle during maintenance and
inspection and a duplex receptacle for
use with electric tools. A molded-case
circuit breaker for space heaters is
located in one cubicle.
Shelter-Clad design – single aisle
The Shelter-Clad switchgear consists of
indoor type circuit breaker and auxiliary
cubicles located in a weatherproof steel
housing having an operating aisle space
of sufficient size to permit withdrawal of
the circuit breakers for inspection, test or
maintenance. An access door is located at
each end of the aisle, arranged so that
the door can be opened from the inside
regardless of whether or not it has been
padlocked on the outside. The aisle space
is provided with incandescent lighting,
which is controlled by means of a three-
way switch at each access door. Each
cubicle includes necessary space heaters.
Each lineup includes two utility duplex
receptacles, one at each aisle access
door, for use with electric tools,
extension cords, etc. The weatherproof
enclosure for the aisle-way is shipped
disassembled for erection in the field.
Optionally, for single-aisle configurations,
the aisle portion of the enclosure can be
shipped assembled.
Shelter-Clad design – common aisle
The Shelter-Clad common-aisle
switchgear consists of two lineups of
indoor type circuit breaker and auxiliary
units located in a weatherproof steel
housing having a common operating
aisle space of sufficient size to permit
withdrawal of the circuit breakers for
inspection, test or maintenance.
Otherwise, the construction is as
described for single-aisle design, except
that the aisle portion is always shipped
disassembled for erection in the field.
Construction
12
Figure 12: Shelter-Clad type GM38 lineup (aisle
portion not shown - refer to Figure 13)
Figure 13: Shelter-Clad single-aisle braced for
shipment