Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 71)

APNE-0016 70
Pinch roller operation, as when the web runs over a metal gravure cylinder
with a rubber impression roller applying pressure to the cylinder.
One must be careful that a high ‘bound’ charge is not captured within the
insulator, lest a condition for highly energetic propagating brush discharges
be established [4,9].
Bound charge investigation requires the use of a properly shielded
electrostatic voltmeter (see www.monroe-
electronics.com/esd_pages/voltmeters.htm) in addition to a fieldmeter, and is
best left to an expert.
Decision Chart Page 2:
Typical locations for verifying low web fields are at hazardous operations
such as rotogravure solvent printing. Measure electric fields after the last
grounded roller (or after any ionizer), but before the gravure printing roller,
and then after the gravure roller (or after any ionizer), but before the next
grounded roller.
High fields that are causing electrostatic discharges (ESD) in a moving web-
converting machine can be quickly located by moving along the machine
holding a portable AM radio tuned off-station in an unused frequency band.
The static heard over the speaker or headphones will increase near the ESD
locations, and may produce a discrete popping noise. The radio picks up the
static discharges because they generate broadband electromagnetic
radiation.
Decision Chart Page 3:
For fields beginning to exceed ±20kV/in on the Model 282A fieldmeter, move
the Model 282A to four inches from the web and observe the reading.
Multiply the reading by a factor of two to obtain the actual field strength, up
to ±40kV/in. If the reading on the 282A begins to exceed ±20kV/in at four
inches, back off to 6.5 inches and multiply the reading by 3 to obtain the
result, up to ±60kV/in. If the reading on the 282A begins to exceed ±60kV/in
at 6.5 inches, back off to 8.5 inches and multiply the reading by 4 to obtain
the result, up to ±80kV/in.Keep in mind that the available web target size
specified in Note 5 needs to increase by a factor of 4 times d.
For both the 282A and 282IS fieldmeters, the minimum distances shown in
Figure II-7 must increase by the indicated factor times the measurement
distance, d (Note 1 & Note 2). These minimum distances must be
maintained to prevent conductive, grounded surfaces from suppressing the
electric field.