Ransburg RMA Indirect A11600 - Manual (Page 28)

In electrostatic coating systems, the flow of
high voltage power from the power supply
to the atomizer is insulated from ground and
isolated from all other functions and equipment.
When the voltage reaches the atomizer, it is
transferred to the coating material where, by
introducing a negative charge, it causes the
atomized fluid to seek the nearest positive
ground. In a properly constructed and operated
system, that ground will be the target object.
The directed conduction of the electric charge
through its array of wires, cables, and equipment,
is accompanied by a variety of stray electrical
charges passing through the air by various means
such as: air ionization, charged particles in the
air and radiated energy. Such charges may be
attracted to any conductive material in the spray
area. If the conductive material does not provide
a safe drain to electrical ground, which will allow
the charge to dissipate as fast as it accumulates,
it may store the charge. When its electrical stor-
age limit is reached, or when it is breached by
external circumstances (such as the approach
of a grounded object or person, or one at lower
potential), it may discharge its stored charge to
the nearest ground. If there is no safe path to
ground (such as a ground wire or braided cable) it
may discharge through the air as a spark. A spark
may ignite the flammable atmosphere of a spray
area. The hazard area extends from the point
of origin up to as much as a twenty-foot radius.
See the NFPA-33 for definition and limitations of
a hazard area.
It is a simple, but vital matter to be sure that all con-
ductive objects within the spray area are grounded.
All cabinets, housing, bases, supports and stands,
which are not by design, insulated from ground,
MUST be connected directly and INDIVIDUALLY
to earth ground. Resting on a concrete floor or
being attached to a building column may not
always be sufficient ground. In order to provide
the best ground connection possible, always at-
tach a ground wire or insulated braided cable to
> Ransburg recommends that ground con-
nections to earth ground be ¾” insulated
copper braided wire. Grounds between
assemblies within a machine should be
ran to a central point within the machine
using #18 insulated stranded copper wire
minimum. All connections should be me-
chanically sound and have less than five
(5) ohms of resistance between assemblies
and the common point. The resistance
between the central point and earth ground
should be less than five (5) ohms as well.
NOTE
the terminal indicated by the ground symbol and
then to a proven ground. Always check ground
connections for integrity. Some items, such as
rotators and paint stands, may be supported on
an insulator, but all components of the system up
to the insulator MUST be grounded.
Where items are mounted directly on structural
components such as building columns, the ground
connection MUST still be made. In many cases
the structural component may be painted or coat-
ed with an insulated material and in all cases the
Ransburg equipment will be painted. These coat-
ings are insulating. The ground connection must
be as perfect as possible. The indicated ground
terminal on the Ransburg equipment will provide
the necessary connection at on end, but the user
must be sure that the other end is secured to an
earth ground. This may be achieved by the use of
a standard ground clamp (properly secured), by
brazing or by piercing the structural component
enough to assure connection. All ground con-
nections should be made to the most conductive
metallic structural ground available.
EQUIPMENT GROUNDING & SAFETY RECOMMENDATIONS
RMA-303 Indirect Charge - Installation
Ransburg
24 LN-9252-06.4