6
HRRS 5kV and 10kV Series
Operation
3.4 Electromagnetic Interference
The HRRS series are resistant to electromagnetic
interference (EMI) because of their metal enclosure
except for the -WT version.
EMI can be a signifi cant source of error when measur-
ing high resistance values.
The green GND binding post on all HRRS Decade
Resistors should be connected to earth ground to
minimize errors due to EMI.
When using the -WT version the GND binding post
should be connected to earth ground however since
the chassis is plastic and not conductive, EMI can
still cause errors during measurement.
Use of a faraday cage is recommended to minimize
EMI especially on the HRRS-WT version. The con-
struction can be as simple as a metal box or enclosure
that is connected to earth ground that is of
suffi
cient
size so that the HRRS-WT can easily fi t inside.
A faraday cage can also easily and inexpensively be
build using copper mesh over a frame. IET Labs
uses a similar faraday cage during calibration of the
HRRS series.
A picture of the a HRRS-WT in our faraday cage can
be seen in Figure 3-1
There are also various pre-manufactured faraday
cages such as THORLABS FAR series. We are not
endorsing this brand but showing options for a com-
mercial off -the-shelf faraday enclosure.
3.5 Storage
If this instrument is to be stored for any lengthy period
of time, it should be sealed in plastic and stored in a
dry location. It should not be subjected to temperature
extremes beyond the specifi cations. Extended expo-
sure to such temperatures can result in an irreversible
change in resistance, and require recalibration.
Figure 3-1: HRRS-WT in faraday enclosure
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