Description Of Function - SCHNIER 810276 Betriebsanleitung

SCHNIER
Der Partner für Elektrostatik

Description of function

The »Manual Coulombmeter« Type HMG 11/02 developed by SCHNIER-
Elektrostatik GmbH together with ELSTATIK and PTB enables directly to
determine the incendivity of brush discharges which arise when the sphere
electrode of the device is being approached towards a charged insulating part.
Coulombmeter
Display
MP
V
R C
Circuit diagram of Manual Coulombmeter
The discharge pulse emitted from the charged insulating object is transferred
via brush discharge to the sphere electrode and will be stored latently in the
capacitor C. Thereafter the discharge pulse is being dissipated to ground via
the resistor R.
The voltage U prevailing temporarily at the R/C-combination will be measured,
multiplied with the capacitance and will result in the charge Q of the discharge
.
pulse: Q = C U.
A microprocessor MP in the Manual Coulombmeter tracks the rising and
declining voltage gradient at the capacitor comparing continuously the
difference between the actual and the previous value. The measurement is
triggered at a defined slope of curve and will be continued until the reversing
point of the voltage gradient is reached. This value will be indicated and
stored.
The voltage resolution is about 1.2 mV at a scanning rate of 10 s. In
exceptional cases it may occur that during a sequence of pulses the scanning
rate may be exceeded and the reversing point will not be reached. Thus the
break-up value is missing and several charge pulses will be determined one
after the other.
The polarity of the charge pulse has no effect on the measuring result but will
be indicated.
Betriebsanleitung 810276BALDEEN090120 Stand 20.01.2008 Seite 15 von 28