4
tubes, and Loose Fill Electrodes for testing loose fill chips. In addition, custom
electrodes and test cages can be designed to meet any special customer requirement.
2.0 EQUIPMENT
DESCRIPTION
2.1 General
The Model 406D Static Decay Meter shown in Figure 2.1-1 is designed to test
the static dissipative characteristics of material by measuring the time required
for a charged test sample to discharge to a known, predetermined cutoff level.
Three (3) manually selected cutoff thresholds at 50%, 10% and 1% (referred in
earlier specifications as 0%) of full charge are provided. Samples are charged by
an adjustable 0 to ±5kV high voltage power supply.
Figure 2.1-1: Model 406D Static Decay Meter
Sample testing may be performed either manually or automatically. In the
Manual Mode, the operator must manually calibrate the unit periodically by
compensating for thermal drift, and by adjusting the full-scale sample charge
point. Further, the operator manually steps the unit through the test sequence by
operating the unit's mode select buttons. In the Automatic Mode, the operator
selects the number of tests to be performed (up to 9) and the time between each
test, sets the full scale sample charge point once, then initiates automatic
testing.
During each test cycle in the Automatic Mode, thermal drift is measured by the
unit's Auto-Zero subsystem and is automatically compensated for. The system
monitors the sample charge and, when the proper level is reached, automatically
starts the discharge and decay time measurement cycle. When the cutoff point
is reached, the unit steps to the Test Over state and displays the decay time
measurement on a four digit LED numeric readout. The test result is displayed
until the interval time (approximately 1-25 seconds) selected by the operator has
lapsed, then, the unit automatically starts another test sequence including Auto-
Zero. Upon reaching the number of pre-selected test cycles, the unit completes
the last test, goes to
TEST OVER
and continuously displays the last decay time
measurement and the number of tests performed.
