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POWER SOURCE AND POWER
REQUIREMENTS
The 492 is designed to operate from a single- phase
power source that has one of its current- carrying conduc
tors ( neutral ) at ground ( earth ) potential . Operating from
power sources where both current- carrying conductors
are isolated or above ground potential ( such as phase-to
phase on a multi -phase system or across the legs of a 110
220
volt
single- phase,
three-wire
system )
is
not
recommended , since only the line conductor has over
current (fuse) protection within the unit. Refer to the
Safety Summary at the front of this manual.
The ac power connector is a three- wire polarized plug
with the ground ( earth ) lead connected directly to the
instrument frame to provide electrical shock protection . If
the unit is connected to any other power source, the unit
frame must be connected to an earth ground .
Power and voltage requirements are printed on a back
panel plate mounted below the power input jack . The 492
can be operated from either a 115 Vac or 230 Vac nominal
line voltage with a range of 90 to 132 or 180 to 250 Vac, at
48 to 440 Hz. A multipin ( harmonica) type connector on
2-2
the power supply etched circuit board can be positioned
to accommodate either voltage range . When the power
supply circuitry is changed to accommodate a different
power source, the information plate on the back panel
must also be changed to reflect the new power re
quirements . Refer power input changes to qualified
service personnel . Instructions are contained in the
Service Information section .
WARNING
Only qualified service personnel should attempt to
change the power input requirements. Unfamiliarity
with safety procedures can result in personal injury.
Refer to the Safety Summary at the front of this
manual.
CONTROLS , INDICATORS, AND
CONNECTORS
The following describes the function of the controls,
indicators , and connectors on the front and rear panels of
the 492. Figures 2-1 and 2-2 illustrate their locations . All
options are covered in this description and some functions
are described in greater depth under Operating Informa
tion .
492 Operator's Handbook
( 8 )
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