IET Labs 1403-9701, Руководство по эксплуатации

Страница: 14 / 17

6
1403 Series
6 Maintenance
3.4 Permittivity Errors
The 1403 series can be used over a wide temperature
range and barometric pressures however it is impor-
tant to understand that both aff ect the permittivity and
therefore the capacitance.
The change of humidity from dry air to 50%
RH results in a around a 1 ppm change in permittiv-
ity and therefore a negligible change in capacitance.
A change in atmospheric pressure from sea level to
1600 meters, results in a change of around 100 ppm
in permittivity and therefore a signifi cant change in
capacitance.
The paper The Measurement and Uncertainty of Air
Dielectric Capacitors from 1 kHz to 10 MHz pro-
vides extremely useful information on the change of
capacitance vs barometric pressure, relative humidity
and temperature for the 1403 Series Air Capacitors.
https://www.osti.gov/servlets/purl/1504063
IET Labs calibrates the 1403 in it’s facility in West
Roxbury, MA. The approximate elevation is 115 feet
(35 meters) above sea level. Given this elevation the
approximate air pressure is 101000 Pa.
3.5 Design of the 1403
The 1403 is a three-terminal standard air capacitor.
The 1403 with capacitance values < 2 pF use three
plates to make up the capacitor element. A high and
low plate which are separated by guard plate. The
guard plate has an aperture of a specifi c diameter for
the capacitance required.
Higher capacitance values use a stack of plates to
make up the capacitor element.
All plates are separated by ceramic shoulder washers
which minimize dissipation factor.
Additional information on the design of the 1403 can
be found at;
https://www.ietlabs.com/pdf/GR_
Experimenters/1959/GenRad_Experimenter_Aug-
Sept_1959.pdf
3.6 Environmental Conditions
3.6.1 Operating Temperature
For optimal accuracy, 1403 models should be used
in an environment of 23°C ±1°C. They should be
allowed to stabilize at those temperatures after any
signifi cant temperature variation.
3.6.2 Storage Temperature
The 1403 units should be maintained within the stor-
age temperature range of 0°C to 40°C to retain its
accuracy within the specifi ed limits.
3.7 Shipping and Handling
The 1403 Series should not be exposed to any excessive
shock or temperature extremes.
3.8 Cleaning and Maintenance
A soft cloth and denatured alcohol can be used for cleaning.
A Q-tip and denatured alcohol can be used to clean the
connectors.
No other maintenance is required.