ESD 42721 Operation And Maintenance

Digital Hand-Held Static Field Meter
Operation and Maintenance
Figure 1. 42721 Digital Static Field Meter
Description
Our 42721 is a high quality, portable
non-contacting static fieldmeter which
produces consistently accurate readings
with ease and provides years of trouble-
free operation. It indicates surface
voltage and polarity on objects up to
±20kV at a spacing of one inch with an
accuracy of 5% of the displayed value.
It is chopper-stabilized for use under
almost any conditions including ionized
environments. Also featured are a push-
button auto-zero and a push-button hold
function. A unique flashing LED
rangefinder system provides accurate
positioning of the meter from the target.
Its accuracy is dependent upon four
factors:
• Grounding of the Field Meter via a
ground cord or a grounded operator.
• The Field Meter must be properly
zeroed.
• The measurement distance from the
front edge of the case to the target or
surface under examination must be
accurately defined.
PS-2061 6/05 Page 1 of 4
• The target must be large relative to
the measurement distance. It should
be at least 5" x 5" for best results.
Inspection
Remove the items from the shipping
carton and inspect for damage. Included
with each unit should be:
1 42721 Digital Field Meter
1 carrying case
1 9V alkaline battery
Operation
ZEROING THE FIELD METER
1. The Field Meter needs only to be
zeroed at the time you first use the
instrument. It will maintain this value
while the battery is charged.
2. Press the ON/ZERO button and
release. The LCD display is activated
and LED rangefinder lights begin to
flash.
3. Ground the operator by using a wrist
strap or a footgrounding device. You
can also ground the unit directly via
a ground cord. The case of the
instrument is conductive and is the
reference for the measurement.
4. Face the Field meter away from
charged objects and press the
ON/ZERO button. Hold until the
display reads zero. The instrument
may also be zeroed by pointing it
toward a known grounded surface
(such as the palm of the opposite
hand) and depressing the ON/ZERO
button. Care should be taken not to
contact the recessed sensor plate,
however the amount of spacing
between the instrument and the target
is not critical when zeroing the
instrument.
Tech Brief
Made in America
Figure 2. Zeroing the Field Meter
TAKING READINGS
1. Point the sensor plate toward the
target and move to a spacing of one
inch from sensor plate to target.
Use the LED rangefinder to
determine this distance. The two
LEDs appear to form a stationary
(not moving) circle on the target at
one inch. Note the meter reading. A
source with a negative polarity shows
a minus (-) sign in the display. A
positive source will display no sign.
To hold the reading, click the
HOLD/OFF button briefly. The
present reading is held and the word
"HOLD" appears in the display. The
rangefinder LEDs go off during the
hold period to conserve battery life.
A second click releases the held
reading.
CAUTION: If, as you approach the
target, the indicated field strength
begins to exceed 20kV at a distance
greater than 1", STOP! This implies
that the target voltage may be high
enough to create an arc. Proceed with
caution.
For measurements in excess of 20kV,
estimate the distance to the target and
use the following multiplying factors:
© 2005 DESCO INDUSTRIES INC.
Employee Owned