Extech Instruments 7470 Operation Manual page 51

3. Press the TEST button.
4. The instrument will now perform the test or connected sequence of tests.
6.5.2. Discharge Function in DC units
The 7472 and 7474 units are equipped with a Discharge function that is designed to
discharge the voltage of a capacitive DUT so that it may be safely disconnected from
the test leads of the instrument. The discharge function monitors the voltage of the
DUT and remains active until the voltage of the DUT falls below 40 volts. The
instrument will also not allow another test to be executed until the voltage of the DUT
falls below 40 volts. The discharge period will occur either directly after the Dwell time,
if Ramp-DOWN is set to "0", or after the designating Ramp-DOWN time.
During the Discharge time, the display will show:
MXX Discharge
XXX.X s
XX.XX KV
If the capacitance of the DUT is very small it is possible that you will not see this display
due to the short amount of time required to discharge the DUT. discharge the DUT.
The voltage and time of the discharging DUT will be displayed during the discharge
period but this information is only intended for reference and cannot be reviewed after
the end of the discharge period. The process signal of the remote I/O remains active
during the discharge period and the high voltage lightning bolt indicator on the front
panel of the instrument is also active during the discharge period.
As a safety precaution, if the RESET button is pressed during the discharge period, the
DO NOT TOUCH THE DEVICE UNDER TEST, HIGH VOLTAGE
TEST LEAD, ALLIGATOR CLIP, OR CLIP INSULATOR ONCE
THE TEST HAS BEEN STARTED.
DO NOT TOUCH THE DEVICE UNDER TEST, HIGH
VOLTAGE TEST LEAD, ALLIGATOR CLIP, OR CLIP
INSULATOR DURING THEDISCHARGE CYCLE.
The Discharge cycle is a means by which the instrument drains
any remaining charge from a DUT after the completion of a test.
The Discharge cycle is active when the word "Discharge"
appears on the screen and is also indicated by the flashing high
voltage lamp, active voltmeter, and timer. Never attempt to
remove a DUT from the instrument during the Discharge cycle.
Always allow the Discharge cycle to complete before powering
down the instrument.
47