iET PRS-300 Series, Руководство по эксплуатации, Страница: 19 / 50

PRS-300 Series
OPERATION 9
3.4.1 Main Display
The main display shows the resistance
value in ohms or temperature value if tables
are used. The main display also shows if the
unit is con
fi gured for 4W (4-wire mode) or 2W
(2-wire mode) in the upper left corner of the
display.
Figure 3-1 Main Display showing 4-Wire
See section 3.2.3 for more information on
2-wire and 4-wire connections.
3.4.2 Setting a Resistance Value
To set a resistance value use the numeric
keypad to enter the value followed by the
ENTER button. The 000 button can be used
to increase the resistance value by a factor of
1000.
The UP and DOWN keys can also
be used to increment or decrement the resis-
tance value. See 3.4.6
INCR Key for more
information.
3.4.3 Menu Button
Pressing the MENU button will show four
selections. See Figure 3-2
Figure 3-2 Menu Screen
Press the numerical value 1 to 4 on the
keypad for the desired selection.
Press the MENU button to cancel and
return to previous screen at anytime.
3.4.4 Standard Values Screen
There are 4 selections available in the
STANDARD VALUES menu. The operation
of the standard values allows the PRS-300 to
be used as an automated resistance carousel
with built-in EIA “preferred value” resistance
tables of 1% (E96), 5% (E24), 10% (E12)
increments or RATIOMETRIC user speci
fi ed
increment.
Figure 3-3 Standard Values Menu
Press the numerical value 1 to 4 on the
keypad for the desired standard values.
Resistors are available in a number of
standard ranges, often called ‘preferred val-
ues’ These ranges, or series, are set out by the
Electronic Industries Association (EIA), and
common values are E12, E24, E48, and E96.
The number after the ‘E’ denotes the number of
values the series contains per decade.
The series are logarithmic and are derived
from the resistor tolerance; resistors with a
tighter tolerance can have more values in the
series that won’t overlap one another. The se-
ries are sometimes referred to by the tolerance,
the two being related as follows:
E12: 10% tolerance
E24: 5% tolerance
E48: 2% tolerance
E96: 1% tolerance
When a STANDARD VALUE is selected
on the PRS-300 pressing the UP or DOWN ar-
rows will increment the resistance value to the