Reduce
uncertainties in your
voltage standard
measurements...
DESCRIPTION
The
Model 98113 Low Thermal
Reversing Switch is a
low cost, easy to use
device that is designed
to mount directly on
the output terminals of
most commonly used
Zener DC voltage
reference standards.
Its design assures
thermal equilibrium
between the Zener
reference terminals and
the contacts of the
switch. Its low thermal
reversing action
assures that the mean
value of forward and
reverse measurements is
the most accurate
possible measurement of
the Zener reference
voltage. Because of its
accuracy, the Model
98113 Low Thermal
Reversing Switch is
used in the NCSLI
Josephson Voltage
Standard
Inter-laboratory
Comparison.
The
Model 98113 Switch
minimizes thermal emf
offset by utilizing an
isothermal design. Both
input and output
conductors are thick
copper plates tightly
clamped to each other
and to the aluminum
body of the switch
through thin Kapton
insulating sheets. The
armatures and
contacting surfaces are
solid silver.
ADVANTAGES
The
key advantage is that
when mounted directly
on the terminals of the
device under test
(DUT), the Model 98113
Low Thermal Reversing
Switch is in thermal
equilibrium with the
terminals and can
detect and eliminate
thermal voltage between
the DUT and your
automated reversing
switch. The Model 98113
Low Thermal Reversing
Switch is manually
operated, and used in
conjunction with an
automated switch. It is
an excellent
troubleshooting device
when there is a
potential problem with
your automated reversal
measurements. By using
the Reversing Switch in
these instances on an
otherwise automated
system you can pinpoint
the source of offset
voltages and reduce
your uncertainties.
SPECIFICATIONS
AND FEATURES
-
Accommodates
terminal spacing of 19
mm to 28.6 mm
-
Fits most
dc reference standards
-
Input:
1.5 mm thick, gold
plated copper lugs
-
Output:
Gold plated TeCu
terminals on 19 mm
centers
-
Typical
Thermal Offset: 3 nV
-
Maximum
thermal offset: 10 nV
-
Rotation
action: + off –
off + off – off
-
Leakage
resistance: Greater
than 100 GW
-
Low
thermal offset voltage
– less than 3 nV
typical
-
Terminal
Mounting
-
Isothermal
Design
PRICE
Price/Quote
available upon request.
TEST
DATA
Typical
dc voltage measurements
use an automated
scanner to connect the
device under test (DUT)
to the measurement
system and to make
forward and reverse
measurements. Thermal
emf's in the scanner
and the wiring between
the scanner and the DUT
are an uncorrected
error in this
measurement. In the
ideal case these
thermal errors are
insignificant but in
reality they often
contribute a
significant part of the
measurement
uncertainty. The HPD
Model 98113 Switch
greatly reduces this
uncertainty. Figure 1
shows two sets of
measurements of a short
circuit made with a
scanner only and with
the scanner in
combination with the
98113 reversing switch.
Points on the left side
of the figure are the
mean value of forward
and reverse
measurements using only
the scanner to reverse
polarity. Points on the
right side of the graph
show the improvement
from using HPD Model
98113 switch.
Even
better performance is
obtained when the Model
98113 is used as the
only switch in the
measurement but this
method may be too labor
intensive for
calibration
laboratories with a
large work load.
