ALLEN BRADLEY 1747-L551 PLC Processor

System Installation Recommendations
3–3
Preventing Excessive Heat
For most applications, normal convection cooling will keep the
adapter components within the specified operating range of 0° C to
+60° C (+32° F to +140° F). Proper spacing of components within
the enclosure is usually sufficient for heat dissipation.
In some applications, a substantial amount of heat is produced by
other equipment inside or outside the enclosure. In this case, place
blower fans inside the enclosure to assist in air circulation and to
reduce “hot spots” near the adapter.
Additional cooling provisions might be necessary when high ambient
temperatures are encountered.
Important:
Do not bring in unfiltered outside air. It may introduce
harmful contaminants of dirt that could cause improper
operation or damage to components. In extreme cases,
you may need to use air conditioning to protect against
heat build-up within the enclosure.
Grounding Guidelines
In solid-state control systems, grounding helps limit the effects of
electrical noise due to electromagnetic interference (EMI). The
ground path for the adapter and its enclosure is provided by the
equipment grounding conductor.
Normal Electrical Noise Conditions
Severe Electrical Noise Conditions
5.2 mm2 (10 AWG)
to Ground Bus
Chassis Mounting Tab
Size M4 or M5
(#10 or #12)
Internal Star
Washer
Chassis
Mounting Tab
Size M4 or M5
(#10 or #12)
Hardware
Ground
Lug
Size M4 or M5
(#10 or #12)
Internal Star
Washers
Size M4 or M5
(#10 or #12)
Hardware
Tapped Hole
(Minimum of Three
Threads)
Tapped Hole
(Minimum of
Three Threads)
Scrape paint off panel to insure
electrical connection between
chassis
and grounded metal panel.
Metal Panel
(Must be connected to
earth ground.)
Scrape paint off panel to insure
electrical connection between chassis
and grounded metal panel.
Metal Panel
(Must be connected to
earth ground.)
Publication 1747-6.2