USER GUIDE | UG:119
PFC MegaPAC-EL
TM
PFC MegaPAC-HPEL
TM
Power Factor Corrected AC-DC Switchers
Contents
Overview
Standard Features
Optional Features
Mechanical Considerations
MegaPAC Dos and Don’ts
Technical Description
Configuring and
Reconfiguring MegaPACs
ConverterPAC Functional
Description
Part Numbering
Page
1
2
2
3
3
4
5
7
8
ConverterPAC Output and
Connector Pin Identification 10
PFC MegaPAC-EL and -HPEL
Quick Install Instructions
11
PFC MegaPAC-EL and PFC
MegaPAC-HPEL
Mechanical Drawing
Interface Connections
Specifications
Output Studs
Output Power Derating
PFC MegaPAC-EL/HPEL
Connector Kit (19-130040)
Listing
Overview
The PFC MegaPAC-EL and PFC MegaPAC High Power Low Noise (HPEL) combine power factor
correction (PFC) with the configurability of the MegaPAC family of power supplies. The
PFC MegaPAC-EL and PFC MegaPAC-HPEL provide up to 1,600W and 2,400W of output power
respectively and have power densities of 4.3W/in
3
and 6.5W/in
3
respectively. The chassis has eight slots
and can provide as many as 16 outputs. The PFC MegaPAC-EL and PFC MegaPAC-HPEL have the same
input and output connections, mounting points and the same dimensions: 3.4 x 6.0 x 15.6in
[85,6 x 152,4 x 396,2mm]. Note that length of older units were 15.5in [393,6mm].
A complete power supply is configured at the factory by selecting and inserting up to eight (four – six
for the PFC MegaPAC-HPEL depending on ConverterPACs used) same length slide-in output assemblies
called ConverterPACs. ConverterPACs™ incorporate one or two VI-200™ / VI-J00™ and / or Maxi Vicor
DC-DC converters and are available in a wide selection of output voltage and power levels. The net
result is a power supply that offers the advantages of a custom supply, but is assembled from standard
and modular building blocks.
Manufactured at Vicor, the entire family of MegaPAC power supplies is completely user-configurable.
If output requirements change, i.e., more power or a different output voltage is needed, upgrading
is easy: simply unlock a single screw and replace the slide-in ConverterPAC assembly with one that is
of the same length and has the desired voltage power rating. For additional flexibility, ConverterPACs
can be connected in parallel to increase output power (booster ConverterPACs), or in series for
higher voltages (total output voltage should not exceed 400V). The driver is to the left of the
boosters when looking at the output end of the supply. A user-friendly interface provides control and
output sequencing capability (see Page 16 for more information about this capability), in addition to
useful status indicators. Please consult our Applications Engineering Department if you have other
special requirements.
14
15
22
23
24
24
Connector Kit for
Dual Outputs only -
MegaPAC Family 19-130042 24
Current Share Boards -
Optional Feature
Current Share Boards -
Optional Feature Diagram
Output Sequencing
25
27
28
Note: This user guide contains references to parts and products that are no longer available for new designs.
They remain included for reference only.
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Standard Features
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Power Factor Correction; 0.99 at 115V
AC
, 0.95 at 230V
AC
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Universal Input: 85 – 264V
AC
, 47 – 500Hz, or 100 – 380V
DC
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Power Outputs:
PFC MegaPAC-EL™:
1,600W at 230V
AC
1,200W at 115V
AC
Up to 16 outputs
PFC MegaPAC-HPEL™:
2,400W at 230V
AC
1,200W at 115V
AC
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Outputs:
PFC MegaPAC-EL and HPEL:
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Cooled
Fan
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Output ripple: 10mV
P-P
or 0.15% whichever is greater
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Full-power to 40°C; half power to 60°C
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start for limiting inrush current
Soft
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Conducted EMI meets FCC Class A and EN55022 A specifications
(some configurations meet Class B. Contact factory)
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Harmonic Distortion to EN61000-3-2
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RoHS compliant available
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Output Sequencing and General Shutdown
(General Shutdown refer to Page 17. Output sequencing refer to Page 28.
Consult Applications Engineering for automatic sequencing circuitry.)
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Overcurrent protection on all outputs
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Overvoltage protection on all ConverterPAC outputs
(not applicable with VI-J00 modules)
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Overtemperature limiting on all ConverterPAC outputs
(not applicable with VI-J00 modules)
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Size: 3.4 x 6.0 x 15.6in [85,6 x 152,4 x 396,2mm]
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Safety Agency Approvals: CE Mark, cTÜVus, UL
Optional Features
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OK status signal
DC
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Current Share Boards - see Pages 25 – 27
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Output voltage adjustment range with built-in potentiometer
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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 20lb.in. The maximum penetration is 0.15in [3.8 mm].
When selecting a mounting location and orientation, the unit should be positioned so air flow is
not restricted. Maintain a 2in 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 30CFM 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 45lb.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™ Dos and Don’ts
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units without Autosense, do not leave ConverterPAC Sense lines open. Always terminate them to
For
their respective output locally or at the load. Use twisted pair 22-24AWG wire. If ConverterPAC has
Autosense, no local-sense connection is required. See Pages 11 and 12 for more information
on Autosense.
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needed, use Connector Kit # 19-130040 for the PFC MegaPAC-EL and PFC MegaPAC-HPEL.
If
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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.
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Always turn the power supply off before disconnecting input or output wires.
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NEVER disconnect the +Out and –Out load wires while the supply is operating, as disconnecting WILL
cause damage to the power supply.
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not unplug ConverterPACs while input power is applied. They are not designed for
Do
hot-plug applications.
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not restrict airflow to the unit. The cooling fan draws air into the unit and forces it out at the
Do
output power terminals.
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power expansion, use booster ConverterPACs™. Viewing the unit from the output terminal side,
For
always insert boosters to the right side of the driver.
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not use boosters as independent outputs. Disconnecting bus bars will damage
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booster ConverterPACs.
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booster arrays, do not remove bus bars.
For
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Always ensure that output hex-nuts are properly torqued before applying power to supply.
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the output (+/–) power cables next to each other to minimize inductance.
Run
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Wait five minutes after shutting off power before inserting or removing ConverterPACs.
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MegaPACs does not have user serviceable components. They must be returned to the factory
The
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.
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Insert proper fault protection at power supply input terminals (i.e., a fuse).
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proper size wires to avoid overheating and excessive voltage drop.
Use
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Never loosen the inner nut on a ConverterPAC.
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Verify output nuts are tight before powering up.
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FinQPACs™ require two slots each because of the larger heat sink attached to dissipate the extra
heat generated by the higher-power Maxi module. Refer to Page 8 for more information on which
ConverterPACs can be used.
Technical Description
The PFC MegaPAC-EL™ and PFC MegaPAC-HPEL™ chassis consists of an offline single phase,
power-factor-corrected front end, EMI filter, cooling fan, low-noise filters, customer interface and
associated housekeeping circuits. Input AC mains voltage (L1, L2 and GND) is applied to a terminal
block. The input current is passed through an EMI filter designed to meet conducted noise limit A
specifications of FCC Part 15, VDE 0871 and EN55022 Class A. At start up, inrush current is limited by a
PTC thermistor. The PTC is shunted out shortly after initial power up by a DC bus voltage Sense circuit
driving a relay. After rectification, the input voltage is put through a boost converter that keeps the AC
input current sinusoidal and synchronized with the AC input voltage (in compliance with EN61000).
The boost converter delivers regulated high voltage DC to the hold-up capacitors and backplane.
The backplane supplies power to a variety of ConverterPAC assemblies that provide the desired
regulated outputs.
Voltage conversion in the output assemblies is achieved by the Vicor family of Zero-Current Switching
(ZCS) DC-DC converters. These are forward converters in which the main switching element switches
at zero current. This patented topology has a number of unique attributes: low-switching losses;
high-frequency operation resulting in reduced size for magnetics and capacitors; excellent line- and
load- regulation; wide-adjustment range for output; low EMI / RFI emissions and high efficiencies.
At initial power up, the PFC MegaPAC-EL and PFC MegaPAC-HPEL outputs are disabled to limit the
inrush current and to allow the DC bus potential to settle out to the correct operating level.
A low-power flyback converter operating with PWM current-mode control converts the high-voltage
DC bus into regulated low voltage to power the internal housekeeping circuits and DC cooling fan. The
internal housekeeping V
CC
comes up within two seconds after the application of input power. Once the
high-voltage bus is within its limits, the AC OK signal asserts to a TTL “1” indicating the input power is
OK and enables the power outputs. An auxiliary V
CC
output of 5V
DC
sourcing up to 0.3A is provided for
peripheral use.
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An output Enable / Disable function is provided by using an optocoupler to control the Gate In pins
of the ConverterPAC™ assemblies. If the Enable / Disable control pin is pulled low, the optocoupler
turns on, pulling the Gate In pin low and disabling the ConverterPAC output. The nominal delay for an
output to come up when measured from release of the Enable / Disable pin is 10 – 15ms. The General
Shutdown function controls all outputs simultaneously and works in a similar manner.
The ride-through (hold-up) time is the amount of time the load can be supported before loss of output
regulation after the loss of input power. Detecting the loss of input power takes a finite time period
after which the AC Power OK signal goes from a TTL “1” to “0." This signal is available for use within
1.2s after initial power up and can be used to indicate an impending loss of power. At least 3ms of
warning time is given. Following the loss of input power, the outputs are disabled when the bus voltage
drops below its operating threshold.
Figure 1
PFC MegaPAC-EL™ and
PFC MegaPAC-HPEL™
low-noise architecture
Input
Line Filter
Rectifier
Waveform
Sample
Current
Sample
Soft Start
Circuit
Boost Converter
High Voltage
DC Bus
QPAC #1
Power
Output
Power
Output
QPAC #2
PFC Control
QPAC #3
Power
Output
Customer
Interface
E/D Control
Enable/Disable Control
Fan
Current
Monitor
Housekeeping
Power
QPAC #8
Power
Output
Configuring and Reconfiguring MegaPACs
Most ConverterPACs of the same length can be inserted into any available slot of a MegaPAC chassis.
They can also be easily added, replaced or moved by sliding the assemblies in or out of a MegaPAC
chassis. For outputs greater than 200W, a driver QPAC™ and one or more booster ConverterPACs will
be used. For outputs greater than 600W, a driver FinQPAC™ and one or more booster ConverterPACs
will be used. Arrays of drivers and boosters should be configured so all boosters are placed in the slots
to the immediate right of the driver when looking at the output end of the MegaPAC.
Prior to removing or installing ConverterPACs, you must remove power from the MegaPAC
and wait five minutes. Failure to do so can result in personal injury or damage to the supply.
Take standard ESD precautions when handling ConverterPACs.
Removing ConverterPACs
ConverterPACs can be removed by loosening the captive screw at the base. Once this screw has been
loosened, the ConverterPAC will slide out of the chassis.
Once a ConverterPAC has been removed,
the empty slot MUST be filled with either another ConverterPAC or an airblock.
If the slot is left
empty, it will provide an airflow escape and cause failure to the power supply.
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