Monroe-electronics Electrostatic Voltmeter - Isoprobe® - model 244A Manuel d'utilisateur télécharger pdf (Page 8)

C. PROBE-TO-SURFACE SPACING:

CAUTION:

When operating at probe-to-surface spacing of less than 0.125 inches (3mm) --

BEWARE OF PROBE-TO-SURFACE ARC-OVER.

Air is subject to dielectric breakdown when the probe-to- surface spacing is low

and the surface voltage is high. A destructive arc-over can occur damaging the

surface under test and/or the sensitive circuitry of the probe.

REFER TO FIGURE 2-1 TO DETERMINE THE SAFE PROBE-TO-SURFACE

SPACING FOR A GIVEN UNKNOWN VOLTAGE.

Probe to surface spacing should be maintained as close as physically reasonable

for best performance. Typical spacing range is from .005" (0.1mm) for unknown

voltages below 500 volts to over .125" (3mm) for unknown voltages up to 3000

volts.

As probe to surface spacing increases instrument performance will suffer:

1. Decreased Accuracy

2. Decreased Speed-of-Response

3. Decreased Surface Resolution

4. Increased Noise

5. Increased Drift

ARC BREAKDOWN VS. PROBE-T O-SURF ACE SPACING

FIGURE 2-1

TYP. BREAKDOWN TEST DATA • = SIDE VIEWING

PROBE-TO-SURFACE SPACING

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 23 24

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Monroe-electronics Electrostatic Voltmeter - Isoprobe® - model 244A Manuel d'utilisateur Page 8