7
Figure 3.0-1b: Model 4431-EV Shielded Bag Test System, laptop computer
This is a turn-key system that performs both the ANSI/ESD STM11.31 and the
EIA 541-1998 shielding bag tests. Depending on the test method selected the
System provides the correct discharge current pulse for both the ANSI/ESD
STM11.31 and EIA 541 tests. The capacitive sensor detects the current pulse or
the voltage differential and sends the signal(s) to the included oscilloscope for
detection and from the oscilloscope to the included computer for processing and
calculation of energy; or attenuated voltage pulses from the direct connection to
the 2-channel oscilloscope for the EIA 541 test.
The Model 4431-EV Shielded Bag Test System consists of the following
components:
3.1.1 Discharge
Unit
1. High voltage power supply with separate ON/OFF switch, adjustable
from approximately 750-1,250 Volts with 3½-digit LED display
2. Switched 100 & 200 pF and 1.5 and 400kOhm discharge networks
3. Mercury wetted discharge relay
4. Floating, programmable capacitive sensor consisting of two 0.875"
diameter precision ground stainless steel electrodes mounted in a
0.625" Delrin base with nominal capacitance of 6 pF
5. Built-in Tektronix CT-1 Current Transducer
6. 100:1 Voltage Attenuators for voltage differential test
7. Lever actuated stainless steel discharge and spring loaded ground
electrodes
8. Discharge electrode grounding relay to remove residual charge
between tests
