Ransburg Voltage Master 2 78789_LEPS5001 - Manual (Page 14)

ELECTRICAL NOISE
Electrical noise refers to stray electrical signals
in the atmosphere at various signal strengths
and frequencies that can affect the operation
of equipment. One of the best ways to prevent
this is to shield the equipment and cables within
a continuous ground envelope, such that any
incident noise will be conducted to earth ground
before it can affect the circuit conductors.
For conductors inside the control panel and power
supply tank, the grounded enclosures provide this
envelope. A conductive gasket has been used
on the control panel door to ensure a continuous
ground envelope between the door and cabinet.
For the control cable that runs from the control
panel to the power supply tank, a shielded cable
has been used. The shield consists of an overall
foil shield in combination with an overall braided
shield. This provides the most effective shielding,
as the foil covers the "holes" in the braid, and the
braid allows for practical 360° termination at both
ends of the cable.
The AC input cord is not shielded, but instead is
directed to an AC line filter as soon as it enters the
cabinet. This filter filters out any noise that comes
in on the AC line. For maximum noise immunity
the AC line should connect to the filter as soon
as it enters the cabinet with as short of leads as
pos-sible. Additional noise protection is provided
by running the AC input line to the control panel
in grounded conduit, which is the recommended
method and is required by most codes.
For maximum noise protection any user supplied
input/output (I/O) wiring should be made using
shielded cable or conduit which is connected to
earth ground in a continuous 360° fashion at both
ends. The best way to do this is to use a connector/
fitting at each end of the cable/conduit that makes
contact to the grounded enclosure in this manner.
Connecting the drain wire of a shield to a ground
point on or in the cabinet (usually referred to as
pigtailing) is not an effective method of shielding
and actually making things worse (see Figure 1).
It is recommended tha all AC I/O (interlocks, DC
pump control, eternal HV ON/OFF, external alarm)
be run in conduit. If desired and codes permit,
cabling may be used for these signals, but for
maximum noise immunity the cabling must contain
overall foil and braided shields and be terminated
as described in the previous paragraph.
Cable is recommended for the DC I/O (analogkV
setpoint in, overload current setpoint in, analog
kV out, analog current out). Again, for maximum
noise immunity the cabling must contain overall
foil and braided shields and be terminated in a
continuous 360° manner as previously described.
Special fittings have been provided on the control
panel for termination of these cables where they
enter the cabinet. The use of these fittings is
described under "DC Remote I/O" in the "Instal-
lation" section of this manual. Using the methods
described above, the Voltage Master 2 has been
successfully tested to the stringent standards of
the Electromagnetic Compatibility Directive of the
European Union. The results conclude that the
Voltage Master 2 is neither a source of electrical
noise nor affected by electrical noise when the
previous methods are utilized.
Voltage Master 2 - Introduction
10
Ransburg
CP-02-02.6