Model
DRC-91c
Section
I
interpolates between data points to for a rhodium-iron to read correct-
an interpolation accuracy which ly in temperature.
exceeds
0.01K
over the entire
temperature range of the Precision The Model DRC-91C with the 9318C
option- The 16 bit analOg-tO- germanium/carbon-glass input card
digital converter is accurate to results
in
the most accurate system
plus or minus
the
least significant For both
bit, which for the
470
series sensors, a precision option is
sensor results in an uncertainty of required to read in temperature.
1mK
below
28K
and
45mK
above
40K
Near
4K,
the overall accuracy of
with a transitional region between the system, including the calibra-
these
two
temperatures. Therefore, tion accuracy, the software
at temperatures below
28K,
the interpolation accuracy and the
overall system accuracy, the
sum
of calculation of the resistance
the instrument accuracy (11mK)
and
results in
an
overall accuracy on
that of the calibration itself the order of
10mK.
(Lake Shore calibrations are
typically better than
20mK
within These input option cards are easily
this region)
is
±
0.03K.
Above installed by the user: thus, units
28K,
system accuracy gradually can be changed or upgraded
to
moderates to a typical value of satisfy changing requirements.
-
+75mK above
40K.
See the Lake
Shore Cryotronics, Inc. Low The ample
memory
space provided in
Temperature Calibration Service the DRC-91C allows several response
brochure for additional discussion curves to be stored in the instru-
of
calibration accuracy. ment. Depending on the complexity
of the
curves,
up to 25 can be
The Model DRC-91C can also be used programmed into the unit.
A
rear-
with the
9220
input
card
which panel DIP switch (Sensor ID) is
handles both diodes
and
positive used to select the particular
temperature coefficient metallic sensor response curve for each
resistors.
,
i.
e.
,
platinum or input.
rhodium-iron resistors. The DIN
curve
is
standard within the The data for calibrated sensors can
instrument and
is
called up be stored in the instrument as an
automatically unless a positive
8001
Precision Option or by the
temperature coefficient precision customer via the IEEE-488 inter-
option is selected by the SENSOR ID face. These curves can contain up
for
that input. The accuracy of to
99
sensor temperature data
the reading
is
dictated by the points. With the standard preci-
sensor and its conformity to the sion option format of
31
data
DIN
curve. The tolerance
on
these points and an
18
character informa-
devices
is
given on the technical tion line, up to twenty curves can
data sheet for the Lake Shore
be
stored.
PLATINUM RTDs. The combined
accuracy of the instrument and a Although data points are stored as
calibrated resistor with a preci- a table, the interpolation al-
sion option is on the order of
40mK
gorithm used results in the
over
the useful range of the sensor equivalent of a high order Cheby-
‘(above
40K
for the platinum). Note chev polynomial calculation in the
that a precision option is required converting of the input voltage
1-2
COPYRIGHT
1/88
LSCI
below
50K
in temperature.