In more detail – Fluke 2625A User Manual
Page 128
2620A, 2625A
Users Manual
1.
Connect the shield to L (low) at the 2620A-100 Input Module, and try connecting the
sensor shield to a quiet earth ground at or very near the measurement sensor end
(and at only one place), or
2.
Connect the shield to L (low) at the Input Module, and try connecting the shield to
earth ground (only) as close to the rear of the instrument as possible. Isolated and
shielded sensors will likely result in the best instrument measurement performance
possible in a noisy environment.
In More Detail
If a low noise configuration is required, adhering to the following two rules minimizes
measurement errors and noise when using shielded sensors and wiring:
1.
Connect the shield so that it and the L (low) terminal are at the same or very nearly
the same voltage, and
2.
Connect the shield so that common-mode voltages will not cause current to flow
through the L (or H) source resistance(s).
One key to applying these rules is to note that very high, but finite impedances exist
between H (high) and L (low), between H and earth ground, and between L and earth
ground inside the instrument.
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