Vicor PFC MegaPAC-HPEL Power Factor Corrected AC-DC Switchers - Manual (Page 3)

UG:119 vicorpower.com Applications Engineering: 800 927.9474 Page 3
Mechanical Considerations
The PFC MegaPAC-EL and PFC MegaPAC-HPEL can be mounted on any of four surfaces
using standard 8-32 or 4 mm screws. The chassis comes with four mounting points on
each surface; maximum allowable torque is 20 lb-in. The maximum penetration is
0.15 in. (3.8 mm).
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-EL and PFC MegaPAC-HPEL 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-EL and PFC MegaPAC-HPEL. The fan moves approximately
30 CFM of air.
Avoid excessive bending of output power cables after they are connected to the PFC
MegaPAC-EL and PFC MegaPAC-HPEL. 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-EL and PFC
MegaPAC-HPEL 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
n For units without Autosense, do not leave ConverterPAC Sense lines open. Always
terminate them to their respective output locally or at the load. Use twisted pair 22-24
AWG wire. If ConverterPAC has Autosense, no local sense connection is required. See
Pages 11 and 12 for more information on Autosense.
n If needed, use Connector Kit # 19-130040 for the PFC MegaPAC-EL and
PFC MegaPAC-HPEL.
n Always fill all output slots of the MegaPAC. If a slot is not filled with a ConverterPAC,
it should be filled with an airblock. Airblocks are plastic assemblies whose main
function is to fill up an empty slot. Any airflow escape from an empty slot
significantly degrades thermal performance, and can result in overheating and
damage to the power supply.
n Always turn the power supply off, before disconnecting input or output wires.
n NEVER disconnect the +Out and -Out load wires while the supply is operating as
disconnecting WILL cause damage to the power supply.
n Do not unplug ConverterPACs while input power is applied. They are not designed for
hot-plug applications.
n Do not restrict airflow to the unit. The cooling fan draws air into the unit and forces it
out at the output power terminals.