Emerson Control Techniques Epsilon Eb-202, Installation Manual, Page: 28 / 134

13
Installation
very little resistance. Impedance cannot be accurately
measured with a standard ohmmeter, because an ohmmeter
measures DC resistance. For example, a 12 inch long 8 gauge
round wire has a significatly higher impedance than a 12 inch
long 12 gauge flat braided conductor. A short wire has less
impedance than a larger one.
Low impedance connections can be achieved by bringing large
areas of conductive surfaces into direct contact with each other.
In most cases this requires paint removal because a ground
connection through bolt threads is not sufficient. However,
component materials should be conductive, compatible and
exhibit good atmospheric corrosion resistance to prevent loss
through corrosion, which will hinder the low impedance
connection. Enclosure manufacturers offer corrosion resistant,
unpainted mounting plates to help.
Bringing components into direct contact cannot always be
achieved. In these situations a conductor must be relied upon
to provide a low impedance path between components.
Remember a flat braided wire has lower impedance than a
round wire of a large guage rating.
A low impedance connection should exist between the following
components, but not limited to:
• Enclosure and mounting plate
• Servo amplifier chassis and mounting plate
• EMI/RFI AC line filter chassis and mounting plate
• Other interface equipment chassis and mounting plate
• Other interface equipment chassis and electrical connectors
• Enclosure and conduit fittings or electrical connectors
• Enclosure mounting plate and earth ground
• Motor frame and conduit fittings or electrical connectors
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