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vicorpower.com
Applications Engineering: 800 927.9474
Page 3
Mechanical Considerations
The PFC MegaPAC can be mounted on any of four surfaces using standard 8-32 or
4mm screws. The chassis comes with four mounting points on each surface; maximum
allowable torque is 5.5 lb-in. The maximum penetration is 0.15 in. (3.8mm).
When selecting a mounting location and orientation, the unit should be positioned
so air flow is not restricted. Maintain a 2" minimum clearance at both ends of the PFC
MegaPAC and route all cables so airflow is not obstructed. The standard unit draws air
in at the fan side/AC input side and exhausts air out the load side. If airflow ducting is
used, use caution, as sharp turns could present back pressure to the PFC MegaPAC. The
fan moves approximately 30 CFM of air.
Avoid excessive bending of output power cables after they are connected to the PFC
MegaPAC . For high-current outputs, use cable ties to support heavy cables in order to
minimize mechanical stress on output studs. Be careful not to short-out to neighboring
output studs. The PFC MegaPAC units are supplied with serrated, flanged hex-nuts on
all output studs. Therefore, thread locking compounds or lock washers are not required.
The maximum torque recommended on flanged nuts is 45 lb-in. Never loosen the inner
nut on a ConverterPAC. This nut supports the hardware inside the ConverterPAC and is
factory torqued.
Avoid applications in which the unit is exposed to excessive shock or vibration levels. In
such applications, a shock absorption mounting design is required.
MegaPAC Do’s and Don’ts
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Remote sense should be used:
- To improve poor output regulation.
- When using older ConverterPACs that do not have the autosense feature.
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NEVER connect the remote sense wires in reverse.To avoid failures, always terminate
the +Sense to the +Out and the -Sense to the -Out.
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If needed, compatible connector kits can be ordered separately. Refer to page 25 for
additional information regarding connector kits.
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To avoid overheating, NEVER operate the supply with an open output slot. Open slots
should always be filled with a ConverterPAC or a plastic airblock designed for
the PFC MegaPAC.
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Always turn the power supply OFF before disconnecting any input or output wires.
Failure to do so may lead to an electrical shock hazard and or damage to
the power supply.
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Do not insert or remove a ConverterPAC while the power supply is running.
They are not designed for hot insertion or extraction.
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Wait 5 minutes after shutting off the power supply before inserting or
removing a ConverterPAC.
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Do not restrict airflow to or from the supply as this can cause overheating damage.
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Booster ConverterPACs are available for power expansion. Refer to page 6 for
additional information.
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Do Not use boosters as independent outputs. Operating boosters with disconnected
bus bars will cause failures.
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Before turning on the unit ensure all input and output wire are properly connected
and all hex nuts properly tightened.
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Keep output wires as short as possible and run the output (+/-) power cables next to
each other. Use twisted pair wiring whenever possible.
