Data Hold; Test Lead Considerations; Voltage Measurements - Extech Instruments EX650 User Manual

Data Hold
To freeze the LCD meter reading, press the H (HOLD) button. While data hold is active, the HOLD
display icon appears on the LCD. Press the H button to return to normal operation. The HOLD icon
will switch OFF.
Test Lead Considerations
Test lead probe covers can be removed for CAT II 1000V installations. Use the test lead probe
covers for CAT III 1000V or CAT IV 600V installations. Do not measure voltages > 1000V AC or DC.
Remove the storage caps from the meter end of test leads before connecting leads to the meter.
Voltage Measurements
WARNING:
Remove the test lead probe covers for CAT II 1000V installations. Use the test lead probe covers
for CAT III 600V installations.
Do not measure voltages greater than 750VAC or 1000VDC.
CAUTION: When connecting the test leads to the circuit or device under test, connect the
black lead before the red; when removing the test leads, remove the red before the black lead.
Disconnect probes and circuit under test after all measurements are completed.
The meter displays a high voltage warning prompt " " when the voltage measured is > 30VAC.
The instrument will automatically beep and show the high voltage warning prompt flashing if the
voltage input exceeds 750VAC or 1000VDC.
Notes:
AC measurements incorporate true RMS AC coupling. The accuracy of non‐sinusoidal waves
must be adjusted as follows:
 Crest factor 1~2, accuracy increases by 3%
 Crest factor 2~2.5, accuracy increases by 5%
 Crest factor 2.5~3, accuracy increases by 7%
In order to obtain accurate readings in the measurement of 600mV, use the relative
measurement mode. First short‐circuit the probe input in, order to zero the reading, and then
press the REL button; now read the voltage measured. The instrument automatically subtracts
the short‐circuit display value of the probe from the reading.
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