Desco 19443 Manual

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Static Field Meter & Ionization Test Kit
Operation and Maintenance
Description
The Desco 19442 Digital Static Field Meter indicates
surface voltage and polarity on objects. The meter has
a measurement range of 0 to ±19.99 kV at a distance of
1 inch and a measurement accuracy of ±5%. It utilizes
a chopper-stablized sensor for use in both normal
and ionized environments. The meter’s enclosure is
dissipative and features a 7 mm snap and ground
cord for bonding to equipment ground. A rotary zero
knob sets the zero-reference point with finely tuned
precision, and a Hold button allows the user to “freeze”
a displayed measurement for evaluation. A LED range
indicator assists with placing the meter at the correct
distance from the object being measured.
The Desco 19443 Air Ionization Test Kit includes and
utilizes the 19442 Digital Static Field Meter to measure
the o󰀨set voltage (balance) and charge decay of
ionization equipment. The Air Ionization Test Kit also
includes a charger used to place a ±1000V charge on
the conductive plate, making it possible to also measure
the discharge times of air ionization equipment per ANSI/
ESD SP3.3 Periodic Verication of Air Ionizers.
Although not as accurate, the Desco Air Ionization Test
Kit is designed to make measurements that correspond
to those made by using a charged plate monitor and
ANSI/ESD STM3.1. The Air Ionization Test Kit provides
convenience and portability to test per ANSI/ESD SP3.3
Periodic Verication of Air Ionizers or Compliance
Verication ESD TR53. Desco recommends using the
770004 or 770005 Charged Plate Analyzer if precise
measurements are required.
All Digital Static Field Meters and Air Ionization Test
Kits are calibrated to NIST standards and include a
certificate.
“When any object becomes electrostatically charged,
there is an electrostatic eld associated with that charge.
If an ESDS (ESD sensitive) device is placed in that
electrostatic eld, a voltage may be induced on the
device. If the device is then momentarily grounded, a
transfer of charge from the device occurs as a CDM
(Charged Device Model) event. If the device is removed
from the region of the electrostatic eld and grounded
again, a second CDM event will occur as charge (of
opposite polarity from the rst event) is transferred from
the device.” (Handbook ESD TR20.20 section 2.7.5 Field
Induced Discharges)
The Digital Static Field Meter, Air Ionization Test Kit,
and its accessories are available as the following item
numbers:
Item Description
19442 Digital Static Field Meter
19443 Air Ionization Test Kit
19440 Conductive Plate and Charger
19441 Conductive Plate
September 2021
Made in the
United States of America
Figure 1. Desco 19442 Digital Static Field Meter
Figure 2. Desco 19443 Air Ionization Test Kit
TECHNICAL BULLETIN TB-3090
5 Commonwealth Ave5 Commonwealth Ave
Woburn, MA 01801Woburn, MA 01801
Phone [phone]Phone [phone]
TollToll Free 1-800-517-8431Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com

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Packaging
19442 Digital Static Field Meter
1 Digital Static Field Meter
1 Coiled Ground Cord, 12' length
1 9V Alkaline Battery
1 Certicate of Calibration
19443 Air Ionization Test Kit
1 Digital Static Field Meter
1 Conductive Plate
1 Charger
1 Coiled Ground Cord, 12’ length
2 9V Alkaline Battery
1 Carrying Case
1 Certicate of Calibration
19440 Conductive Plate and Charger
1 Conductive Plate
1 Charger
1 9V Alkaline Battery
1 Carrying Case
19441 Conductive Plate
1 Conductive Plate
Features and Components
Digital Static Field Meter
Figure 4. Digital Static Field Meter features and
components
C
B
Figure 3. Air Ionization Test Kit and Carrying Case
A. Display: Displays the measured value in kV/inch.
B. Rotary Zero Knob: Sets the 0 volt reference point.
C. Power Switch: Slide to the left to power the meter o󰀨.
Slide to the right to power the meter on.
D. Measure/Hold Pushbutton Switch: Press the
pushbutton to display live measurements. Release the
pushbutton to freeze the measurement on the display.
The red LED above the pushbutton will illuminate when
HOLD is enabled.
E. 7 mm Ground Snap: Connect the included 7 mm
coiled ground cord here to ground the meter.
F. Battery Cover: Slide the cover down to open the 9V
battery compartment.
F
A
D
E
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Operation
Digital Static Field Meter
NOTE: The Digital Static Field Meter’s enclosure is
conductive. The instrument senses the di󰀨erence in
potential between the enclosure and the tested surface.
The meter must be grounded by either the hand of a
grounded operator or the included coiled ground cord to
achieve accurate measurements.
Zeroing the Digital Static Field Meter
Slide the power switch to the right to power the Digital
Static Field Meter. Point the top of the Digital Static
Field Meter approximately 1 inch (2.5 cm) away from
a grounded metal surface. Proper spacing is indicated
when the two red bullseyes emitted LED range indicator
become centered on top of each other. Turn the rotary
zero knob until the Digital Static Field Meter’s display
reads 0.00.
Charger
Figure 5. Charger features and components
A
B
C
D
A. Output Contact: The output contact is connected to
an internal power source. When the touch plate located
underneath the unit is connected to ground, the output
contact will provide a charge of the indicated polarity.
The charger is designed so that an operator can press
the rocker switch and touch the plate simultaneously
with the ngers of the same hand.
B. Rocker Switch: Press and hold to select the polarity
that will be provided at the Output Contact.
C. Touch Plate: Make contact with the touch plate while
pressing down the rocker switch to provide voltage to the
Output Contact. The operator must be properly
grounded during use.
D. Battery Compartment: Slide the cover down to open
the 9V battery compartment.
Figure 6. Pointing the Digital Static Field Meter to a
grounded surface
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Performing a Measurement
Use the LED range indicator to position the top of the
Digital Static Field Meter 1 inch (2.5 cm) from the object
to be measured. The Digital Static Field Meter will
display a reading (from 0 to ±19.99) of the electrostatic
eld in kilovolts per inch.
NOTE: The display will indicate “1” or “-1” when the
Digital Static Field Meter is over-ranged. Change the
range of the unit if necessary. If the measurement
exceeds 20 kV, move the Digital Static Field Meter
farther away from the object and multiply the reading
by the distance (in inches) away from the object being
measured. The measurement accuracy is dependent
on a stable ground reference and the 1 inch measuring
distance. It is also dependent on the “aspect ratio”,
relating the size of the object to be measured to the
measurement distance.
NOTE: This aspect ratio should be at least 3 for best
accuracy. In other words, the object should be at least
a 3 inch square when measuring at a 1 inch distance.
Accurate measurements may be made at other
measurement distances by scaling the Digital Static
Field Meter range and observing the proper aspect ratio.
For example, at a measurement distance of 3 inches,
multiply the Digital Static Field Meter reading by 3 to
give a range of 0 to 60 kilovolts. For accuracy, the object
being measured at this distance should be at least a 9
inch square.
Holding the Last Reading
With the Digital Static Field Meter positioned 1 inch
(2.5 cm) from the object being measured, press the
red pushbutton switch into the HOLD position. This will
freeze the measurement on the display and illuminate
the red LED located above the pushbutton switch. This
feature allows the operator to move the Digital Static
Field Meter where it may be more easily read or saved
for later reference.
NOTE: The LED range indicator will disable while the
Digital Static Field Meter is in HOLD mode. Use the
HOLD feature between measurements to prolong the
battery’s life.
Air Ionization Test Kit
Performing O󰀨set Voltage (Balance) Measurements
The Air Ionization Test Kit has been designed to match
the
compact size and hand held convenience of the Digital
Static Field Meter. Use the following procedure to verify
the o󰀨set voltage (balance) of air ionization equipment.
This quick and easy procedure will help determine if
the piece of ionization equipment is working within the
manufacturer’s specications or user requirements. It is
extremely important that ionizers be checked regularly
for o󰀨set voltage (balance) and discharge times.
An ionizer operating in an out-of-balance state can
place a charge on sensitive electronic components or
assemblies.
NOTE: The Digital Static Field Meter’s enclosure is
conductive. The instrument senses the di󰀨erence in
potential between the enclosure and the tested surface.
The meter must be grounded by either the hand of a
grounded operator or the included coiled ground cord to
achieve accurate measurements.
Installing the Conductive Plate
The Digital Static Field Meter’s case has two slots
along its sides. The top slot is closest to the face of the
instrument. Slide down the tabs of the Conductive Plate
plate into the top slot of the Digital Static Field Meter’s
case as far as they go.
Figure 7. Aligning the two bullseyes emitted by the LED
range indicator
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Zeroing the Digital Static Field Meter
Slide the power switch to the right to power the Digital
Static Field Meter. Make contact between the top of
the Conductive Plate and a grounded surface. Turn the
rotary zero knob until the Digital Static Field Meter’s
display reads 0.00.
Performing a Measurement
Locate the Test Kit in an ionized environment at the
appropriate distance from the device under test. The
static eld displayed is the actual balance of the ionizer
or voltage o󰀨set. The display will indicate “1” or “-1”
when the Digital Static Field Meter is over-ranged.
Change the range of the unit if necessary.
NOTE: When testing pulsed ionizer systems, the voltage
displayed is constantly changing. This pulse rate may
be faster than the display update rate of the Digital
Static Field Meter, therefore the displayed voltage is an
average of the actual voltage. The output of the Digital
Static Field Meter is useful in this situation for more
accurate measurements.
Holding the Last Reading
Press the red pushbutton switch into the HOLD position.
This will freeze the measurement on the display and
illuminate the red LED located above the pushbutton
switch. This feature allows the operator to move the
Digital Static Field Meter where it may be more easily
read or saved for later reference.
Performing Discharge Time Measurements
In order to verify that an ionizer is operating properly it is
also important that its ability to neutralize or discharge
static electricity is measured. The following procedure
will measure an ionizer’s discharge time:
Operating the Charger
The Charger has a momentary rocker switch that powers
the unit. Holding the switch forward / backward supplies
power to the output terminals.
Polarity Selection
The top of the rocker switch is labeled “+”, and the
bottom is labeled “-”. To provide a POSITIVE voltage
output, touch the plate located underneath the charger,
and press the switch forward at the same time. To
provide a NEGATIVE voltage output, touch the plate
located underneath the charger, and press the switch
downward at the same time.
NOTE: For the Charger to work correctly, the operator
and Digital Static Field Meter must be properly
grounded. A ground path to the touch plate must exist.
Ionizer Discharge Time
Use the Digital Static Field Meter with the Conductive
Plate in the appropriate location for measurements.
Figure 8. Sliding the Conductive Plate onto the Digital
Static Field Meter
Figure 9. Using the Digital Static Field Meter with
Conductive Plate to measure the oset voltage of a
benchtop ionizer
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Positive Discharge Time Measurements
To provide a POSITIVE voltage output, touch the
plate located underneath the Charger, and press the
switch forward at the same time. Momentarily touch
the Charger’s output terminal to the conductive plate
attached to the Digital Static Field Meter. The Digital
Static Field Meter reads approximately +1.10 kV. By
using a stop watch or other timing device, determine the
time needed for the voltages to decrease from +1.10 kV
to +0.10 kV. This is the positive discharge time.
Negative Discharge Time Measurements
To provide a NEGATIVE voltage output, touch the plate
located underneath the Charger, and press the switch
downward at the same time. Momentarily touch the
Charger’s output terminal to the conductive plate
attached to the Digital Static Field Meter. The Digital
Static Field Meter reads
approximately -1.10 kV. By using a stop watch or other
timing device, determine the time needed for the
voltages to decrease from -1.10 kV to -0.10 kV. This is
the negative discharge time.
NOTE: A ground path must be provided between the
touch plate of the Charger and the ground reference of
the Digital Static Field Meter. This is normally provided
by holding the Charger in one hand and the Digital Static
Field Meter with Conductive Plate in the other.
Maintenance
The Digital Static Field Meter and Charger are factory
calibrated and no maintenance is required. Contact
Desco Customer Service should the products behave
abnormally. Any unauthorized service will void the
warranty and result in additional repair charges.
NOTE: This Digital Static Field Meter is a precision
instrument and should not be subjected to dropping as
that would void the warranty.
Replacing the Battery
The Digital Static Field Meter’s battery should be
replaced when a battery symbol appears on the display.
The battery in the Charger should be replaced annually
or when it is unable to provide approximately ±1100V.
Always replace the batteries with a 9V alkaline or
equivalent battery.
Cleaning
The area around the aperture of the Digital Static Field
Meter must be kept clean to ensure accurate, drift-free
readings. Never touch the aperture. Use low-pressure
instrument-grade air to remove dust or other debris. To
remove more severe contamination, spray or ush with
the smallest practical amount of clean technical-grade
of isopropyl alcohol. Allow the instrument to air dry for
several hours afterward.
Keep the insulators on the Aluminum Conductive Plate
clean and free of contaminates that may cause surface
leakage. To test the performance of the Conductive
Plate, charge the plate and note the discharge rate in
a non-ionized area. The self discharge rate to 10% of
original voltage should be greater than ve minutes.
Figure 10. Using the Charger to apply a charge onto the
Conductive Plate
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Calibration
Digital Static Field Meter
Routine calibration is not required. There are no user
serviceable parts. Contact Desco Customer Service
should the Digital Static Field Meter exhibit any
abnormal behavior. Any unauthorized service will void
the warranty and result in additional repair charges.
Specications
Digital Static Field Meter
Performance
Measurement Range 0 to ±19.99 kV / inch
Measurement Accuracy Better than ±5% of reading,
±2 counts
Measurement Stability ±10 counts
Front Panel Meter
Voltage Display 3-1/2 digit LED display
Sampling Rate 3 readings per second
Features
Ranging System LED distance indicator;
aligned targets indicate 1"
Range LED distance indicator
Rotary Zero Knob Sets the zero-reference point
Low Battery Indicator An LCD icon indicates when
the battery is low
Hold Switch Retains the LCD display
reading when depressed
General
Dimensions 0.9" H x 2.8" W x 4.9"L
(24 mm x 70 mm x 126 mm)
Weight 4.9 oz. (140 g) with battery
Operating Conditions
Temperature 50 to 86ºF (10 to 30ºC)
Relative Humidity To 80%, non-condensing
Altitude To 2000 m
Certications CE
Power Requirements
Power One (1) 9-volt alkaline battery
Operating Time Greater than 50 hours,
with a new battery at 21ºC
continuous
Air Ionization Test Kit
Conductive plate
Assembly
Aluminum bracket, bare
aluminum plate and teon
spacers isolate plate from
bracket
Voltage Output 1/10,000 of measured voltage
Conductive plate Area 2.95" W x 1.18" L
(7.5 x 3.0 cm)
Conductive plate
Assembly Weight
2.4 oz. (68 g)
Charger Dimensions 1.1" H x 2.6" W x 4.5" L
(2.8 x 6.6 x 11.4 cm)
Charger Weight 5 oz. (140 g) with battery
Charger Power
Requirements
One 9-volt alkaline battery
Charger Output (using
Digital Static Field
Meter with conductive
plate)
1.1 kV minimum for ± voltage
Certications CE
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