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Operation
Arc Detection
The primary method to prevent arcing to the
workpiece is to keep the charged components
of the applicator at least 6 in. (15.2 cm) away
from the workpiece at all times. In addition, the
Electrostatic Controller is equipped with a feature
called arc detection. When the controller detects
conditions suitable to create an arc, the arc detection
circuitry disables the power supply drive circuitry and
produces an arc detection error. The power supply
drive circuitry remains disabled until the error has
been confirmed by the user or the PLC.
The arc detection circuitry helps minimize the risk of
arcing, but a 6 in. (15.2 cm) minimum safe distance
must be maintained at all times.
Check Arc Detection Function
To avoid fire or explosion during the test, all spraying
devices in the hazardous area must be turned off
and ventilation fans in the hazardous area must be
operating. Conduct the test only when no flammable
vapors are present in the area (such as open solvent
containers or fumes from spraying).
To verify the proper operation of the arc detection
follow the test procedure from EN standard 50176.
The test must be conducted after all system
parameters have been set but before operation. The
arc detection test should be repeated periodically
and any time the system parameters are changed.
Repeat yearly at a minimum. The test verifies that
the arc detection is functioning correctly, so the
equipment detects the possibility of a static arc
and the electrostatics turn off before any spark
is discharged. An error code of H15, H16, H17,
or H18 should display. An example method of
testing is provided in the next two sections, first for
stationary/reciprocator systems and then for robot-
mounted systems.
For Stationary Systems and Reciprocators
Follow the general procedure for robot-mounted
systems (next section), but manually approach the
stationary cup with a grounded plate or rod at a
speed that simulates production conditions.
For Robot-Mounted Systems
The test can be conducted with Grounded Test
Plate Kit 25C424, purchased separately. Users
54
also may supply a grounded plate that meets the
requirements specified in the illustration. The test
must be conducted with no fluid in the applicator and
the shaping airs off.
1. Record the temperature, relative humidity, and
air pressure in the operating environment.
2. Position the test plate so that it is aligned at the
center with the cup. See illustration.
3. Connect the test plate to a true earth ground.
4. Set the starting distance between the test plate
and the cup electrode to 0.5 cm/kV of the set
output voltage of your system. For example, if
your output voltage is set to 50 kV, the plate and
the cup must be placed at least 25 cm (10 in.)
apart.
5. Set the approach speed of the robot so that it
is 1.2 times the maximum movement speed of
the robot during spraying operation, at least 500
mm/second.
6. Activate the electrostatics and approach the
grounded target to within 1 cm.
7. Perform the test five times. Each time, the
electrostatics must turn off before any visible
spark occurs between the electrodes.
8. Increase or decrease the sensitivity of the arc
detection settings as needed to pass the test.
See
Arc Detection Adjustments, page
A 6 in. (15.2 cm) minimum safe distance must still be
maintained during spraying operations.
To avoid fire and explosion, the correct operation
of the arc detection function must be tested
periodically. The test must be repeated every 6
months and anytime the system parameters are
changed.
55.
3A3657C
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