MD 9250 Clamp Meter Series
Operation
9
*Ghost-voltage Buster: Ghost-voltages are unwanted stray signals coupled from
adjacent hard signals, which confuse common multimeter voltage measurements. Our
AutoCheck
TM
mode provides low (ramp-
up) input impedance (approx. 2.5kΩ at low
voltage) to drain ghost voltages leaving mainly hard signal values on meter readings. It
is an invaluable feature for precise indication of hard signals, such as distinguishing
between hot and open wires (to ground) in electrical installation applications.
WARNING:
AutoCheck
TM
mode input impedance increases abruptly from initial 2.5kΩ to a few
hundred kΩ’s on high voltage hard signals. “LoZ” displays on the LCD to remind the
users of being in such low impedance mode. Peak initial load current, while probing
1000VAC for example,
can be up to 566mA (1000V x 1.414 / 2.5kΩ), decreasing
abruptly to approx. 3.37mA (1000V x 1.414 / 420kΩ) within a fraction of a second. Do
not use AutoCheck
TM
mode on circuits that could be damaged by such low input
impedance. Instead, use rotary-switch selector or
high input impedance voltage
modes to minimize loading for such circuits.
VFD-ACV
Hz
& ACV
Hz
functions
Inputs are made through the test leads terminals.
VFD-ACV
Hz
function is to deal with VFD (Variable Frequency Device) signals. It,
however, further pre-selects the most appropriate voltage-ranges and thus the Hz
trigger levels to best cope with most VFD-Voltage and VFD-Frequency applications.
Note: The Hz trigger level is determined by the
AC/DC+AC Voltage or Current
function-range being in use. Press
RANGE
button to select different function-ranges
and thus trigger levels manually.
DCV & DC+ACV
Hz
functions
Inputs are made through the test leads terminals. Defaults at
DCV
Function. Press
SELECT
button momentarily and release to select
DC+ACV
Hz
.
