Specifications
Mechanical Considerations
The PFC MegaPAC-EL and PFC MegaPAC-HPEL 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 20 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-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 fac-
tory 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
• 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 page 10 and 13 for more information on Autosense.
• If needed, use Connector Kit # 19-130040 for the PFC MegaPAC-EL and PFC MegaPAC-HPEL.
• 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 dam-
age to the power supply.
• Always turn the power supply off, before disconnecting input or output wires.
• When using the remote sense feature, the +Out and -Out load wires should never be disconnected while the
supply is operating. Failing to do so could damage the power supply.
• Do not unplug ConverterPACs while input power is applied. They are not designed for hot-plug applications.
• Do not restrict airflow to the unit. The cooling fan draws air into the unit and forces it out at the output power
terminals.
• For power expansion, use booster ConverterPACs. Viewing the unit from the output terminal side, always
insert boosters to the right side of the driver.
• Do not use boosters as independent outputs. Disconnecting bus bars will damage booster ConverterPACs.
• For booster arrays, do not remove busbars.
• Always ensure that output hex-nuts are properly torqued before applying power to supply.
• Run the output (+/–) power cables next to each other to minimize inductance.
• Wait 5 minutes after shutting off power before inserting or removing ConverterPACs.
• The MegaPACs does not have user serviceable components. They must be returned to the factory for repairs.
Contact Customer Service for a RMA number before returning the unit. Do not attempt to repair or modify
the power supply in any manner other than the exchange of ConverterPACs as described in this Design Guide.
• Insert proper fault protection at power supply input terminals (i.e., a fuse).
• Use proper size wires to avoid overheating and excessive voltage drop.
• Never loosen the inner nut on a ConverterPAC.
• Verify output nuts are tight before powering up.
• FinQPACs require 2 slots each because of the larger heatsink attached to dissipate the extra heat generated by
the higher power 2nd Gen module Refer to page 7 for more information on which ConverterPACs can be
used.
• Older PFC MegaPAC-ELs cannot use the 2nd Gen FinQPAC ConverterPAC because of chassis differences.
Pg 4 Vicor 800-735-6200 Westcor Division 408-522-5280 Applications Engineering 800-927-9474 Rev. 6/2004
PFC MegaPAC-EL/PFC MegaPAC-High Power Low Noise