Campbell CS110, Инструкция по эксплуатации, Страница: 11 / 86

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CS110 Electric Field Meter
1. General Description
1.1 CS110 Introduction
Atmospheric electric fields have been measured for decades by electric field
meters nicknamed “field mills”. Traditional field mills employ a spinning metal
rotor (vane) electrically connected to Earth ground, placed between the external
field and stationary metal sense electrodes. The grounded spinning rotor
alternately shields and exposes the sense electrodes from the electric field to be
measured, resulting in a modulation of the induced charge on the sense electrodes.
Typically, a pair of charge amplifiers converts the modulated charge into AC
voltages that are synchronously rectified and filtered to form a low-frequency
voltage proportional to the low-frequency (
≤
10 Hz) electric field.
Figure 1. CS110 Electric Field Meter
Unlike traditional rotating vane field mills, the CS110 uses a reciprocating shutter.
A stepper motor opens and then closes the reciprocating shutter by 45
°
during
measurements. The reciprocating shutter is electrically connected to ground
potential by a flexible stainless-steel strap operated below its fatigue limit,
resulting in an ultra-reliable electrical ground connection. The CS110 offers
improved dc error performance, as compared with traditional rotating vane field
Case Lid
Ground Strap
Sealed Connectors
Reciprocating Shutter
Stator