6
SCA Series
6
Maintenance
4.3 Calibration Procedure with
Digibridge
To calibrate an SCA unit, proceed as follows:
1. SCA capacitors with bnc connectors should
be connected to the Digibridge such that the
shields are connected to both the high and
low terminals.
2. Determine and employ proper metrological
practices.
Allow a con
fi
dence band for the uncer-
tainty of the measuring instrument and
setup.
3. Set test conditions:
At 1 Vrms, series model, 23°C
≤
190 pF: 3-terminal measurement
bnc connection
1nF - 1
μ
F: 3-terminal measurement
binding post connection
≥
1.9
μ
F: 5-terminal measurement
binding post connection
4. Determine the allowable drift limits for the
capacitance reading.
<(0.1%+0.1pF) per year - up to 1
μ
F
5. Con
fi
rm that the readings fall within these
drift limits, allowing for the uncertainty band.
If the reading falls outside the limits,
it has to be repaired by IET or another
quali
fi
ed facility.
4.4 Calibration Procedure with
GenRad 1620 or AH2500A/
AH2700A Capacitance Bridge
To calibrate an SCA unit, proceed as follows:
1. SCA capacitors with bnc connectors should
have the shield disconnected at the
HI
termi-
nal to minimize stray capacitance. The shield
on the LO terminal should be maintained.
This connection mimics the connection on the
IET/GenRad 1404 Standard Capacitor.
2. Determine and employ proper metrological
practices.
Allow a con
fi
dence band for the uncer-
tainty of the measuring instrument and
setup.
3. Set test conditions:
At 1 Vrms, series model, 23°C
≤
190 pF: 3-terminal measurement
bnc connection
1nF - 1
μ
F: 3-terminal measurement
binding post connection
≥
1.9
μ
F: 5-terminal measurement
binding post connection
4. Determine the allowable drift limits for the
capacitance reading.
<(0.1%+0.1pF) per year - up to 1
μ
F
5. Con
fi
rm that the readings fall within these
drift limits, allowing for the uncertainty band.
If the reading falls outside the limits,
it has to be repaired by IET or another
quali
fi
ed facility
