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©
Fraser Anti-Static Techniques Ltd
2015
3. Characteristics of the Electric Field
The electric field has unusual characteristics which should be understood when
making electrost atic measurements. These are noted below.
The electric field lines of the static charge radiate vertically from the object. But
they are easily distorted by adjacent machinery parts. When the material to be
measured is touching a part of the machine, such as a roller it is impossible to
make an accurate reading. This is shown in the sketch below.
Rule
For a true reading, measure the object when it is in free air and away from
machine parts. If this is not possible, accept that the display is under-measuring
the charge. This is an important
factor when taking readings in confined spaces. The material should never
be measured when touching another body. This phenomenon is easier to
understand if you charge a sheet of plastic by rubbing it. Then move the sheet
towards a wall, with the EX715 measuring the charge at all times. The reading
will be about zero when the sheet touches the wall, but will return to its previous
level when the sheet is moved away.
Characteristics of the Electric Field
The electric field has unusual characteristics which should be understood when making
electrostatic measurements. These are noted below.
The electric field lines of the static charge radiate vertically from the object. But they are easily
distorted by adjacent machinery parts. When the material to be measured is touching a part of
the machine, such as a roller it is impossible to make an accurate reading. This is shown in the
sketch below.
Rule:
For a true reading, measure the object when it is in free air and away from machine parts. If this is
not possible, accept that the display is under-measuring the charge. This is an important
factor when taking readings in confined spaces. The material should never be measured when
touching another body.
This phenomenon is easier to understand if you charge a sheet of plastic by rubbing it. Then
move the sheet towards a wall, with the EX715 measuring the charge at all times. The reading will
be about zero when the sheet touches the wall, but will return to its previous level when the sheet
is moved away.
Operating Instructions
The earth lead must be used to connect the instrument to a suitable grounded point during
operation. This prevents charge building up in the instrument and distorting the reading, or
stud should be connected to a suitable earth, such as a bare metal part of the machine.
1.
Hold EX715 in the palm of hand, point it away from the charge and click the button once to
turn ON. This sets the zero level for readings, so it must be pointing away from the charge
when the button is clicked.
2.
Hold the instrument 100mm from the object to be measured and observe the reading on
the LCDdisplay. It shows the surface voltage of the static charge in kilovolts. he polarity of
the charge is positive unless a negative sign is shown on the display.
3.
Click the button again to HOLD the reading. When the reading is on HOLD it blinks/ flashes.
4.
To take another measurement, re-zero the instrument by clicking the button when it is
pointing into free air away from the charge. The HOLD function stops and the EX715 is
ready to take another reading.
5. The EX715 turns itself OFF automatically after about 60 seconds.
6.
Do not take a measurement within 300mm of a static eliminator, as the ionised air will
distort the reading.
7.
Replace the 9V PP3 battery when “Battery Low” indicator shows on display. Access is
through the removable plate in the bottom of the instrument. For battery type see next page.
Film
Field becomes coupled to
roller and distorted
Field Lines
Field returns when film
leaves roller
Instructions/Booklet/EX715 iss 4
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Summary of Contents for EX715
Page 1: ...EX715 STATIC METER OPERATING INSTRUCTIONS ...
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