| 摘要 |
<p>Apparatus for measuring the capacitance to ground of a plate, the apparatus comprising: a sample capacitor Cs having two terminals, a proximal one of the two terminals being connected to the plate and the second terminal being distal from the plate; a voltage measuring or sensing means (14) connected to one of the terminals of the sample capacitor; at least three switching elements, S1, S2, S3 each of the at least three switching elements having both a respective open state and a respective closed state; wherein: a first of the switching elements S1 connects the distal terminal of the sample capacitor to a first predetermined voltage when in its closed state; a second of the switching elements S2 connects the proximal terminal of the sample capacitor to a second predetermined voltage different from the first predetermined voltage when in its closed state; and the third switching element S3 connects the distal terminal of the sample capacitor to the proximal terminal of the sample capacitor when in its closed state; and a control means adapted to operate the three switching elements so that at any time at least one of the three switching elements is in its respective open state.</p> |
