USER GUIDE | UG:105
PFC MegaPAC
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
6
8
ConverterPAC Output and
Connector Pin Identification
for the PFC MegaPAC
10
PFC MegaPAC
Quick Install Instructions
PFC MegaPAC
Mechanical Drawing
Interface Connections
Output Studs
PFC MegaPAC
Output Power Derating
12
15
16
24
25
Overview
The PFC MegaPAC family of supplies combine Power Factor Correction (PFC) with the inherent
configurability of all Vicor MegaPAC products. This design guide covers four model variations:
1.
2.
3.
4.
PFC MegaPAC
PFC MegaPAC MI
PFC MegaPAC High Power
PFC MegaPAC High Power MI
1600W max, standard chassis
1600W max, rugged COTS chassis
2400W max, standard chassis
2400W max, rugged COTS chassis
All PFC MegaPACs have the same input and output connections, mounting points and the
same dimensions:
The extended length (-EL) chassis is covered in a different design guide.
A complete power supply is configured at the factory by selecting and inserting up to eight same-length
slide-in output assemblies called ConverterPACs™. ConverterPACs incorporate one (or more)
VI-200 / VI-J00. Maxi Vicor DC-DC converters 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. Currently, the standard-power chassis uses
ConverterPACs with VI-200™ / VI-J00™ Vicor DC-DC converters while the high-power chassis accepts
ConverterPACs with both VI-200 / VI-J00 and / or Maxi module. (Refer to Page 7 for a brief overview of
the ConverterPACs used).
PFC MegaPAC Connector Kit
(43075) Listing
25
Current Share Boards -
Optional Feature
Current Share Boards -
Optional Feature Diagram
Low Leakage Version
Output Sequencing
26
28
29
30
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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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 30 for more information about this capability), in addition to useful
status indicators. Please consult our Applications Engineering Department if you have other special
requirements.
Standard Features
n
Power Factor Correction; 0.99 at 115V
AC
, 0.95 at 230V
AC
- both at full load (47 – 63Hz)
n
Universal Input: 85 – 264V
AC
, 47 – 500Hz or 100 – 380V
DC
n
Power Outputs:
Standard Chassis:
1,600W at 230V
AC
1,200W at 115V
AC
n
Outputs:
Standard Chassis:
Up to 16 outputs
n
Cooled
Fan
n
Full-power to 40°C; half power to 60°C
n
start for limiting inrush current
Soft
n
Conducted EMI meets FCC Class A and EN 55022 Class A
Some configurations meet Class B; Consult Factory
n
Harmonic Distortion to EN61000-3-2
n
RoHS compliant available
n
Output sequencing and general shutdown
(Refer to Page 30. Consult Applications Engineering for automatic-sequencing circuitry)
n
Overcurrent protection on all outputs
n
Overvoltage protection and overtemperature limiting on all ConverterPAC outputs
(not applicable with VI-J00)
n
Size: 3.4 x 6.0 x 12.4in [313,9 x 152,4 x 309mm]
n
Safety Agency Approvals: cURus, cTÜVus, CE Mark
High Power Chassis:
2,400W at 230V
AC
1,200W at 115V
AC
High Power Chassis:
Up to 16 outputs
Optional Features
n
OK status signal
DC
n
Current Share Boards: see Pages 26 – 28
n
Output voltage adjustment range with built-in potentiometer
n
Low leakage version available upon request: see Page 29
n
–40°C operation
n
Conformal coating (MI versions only)
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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 0.15in [3.8mm].
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 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 30CFM 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 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
n
Remote sense should be used:
n to
improve poor output regulation.
n when
using older ConverterPACs that do not have the autosense feature.
n
NEVER
connect the remote-sense wires in reverse. To avoid failures,
always terminate the +Sense to the +Out and the –Sense to the –Out.
n
needed, compatible connector kits can be ordered separately.
If
Refer to Page 25 for additional information regarding connector kits.
n
avoid overheating,
NEVER
operate the supply with an open output slot. Open slots should always
To
be filled with a ConverterPAC or a plastic airblock designed for the PFC MegaPAC.
n
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.
n
NOT
insert or remove a ConverterPAC while the power supply is running.
DO
They are not designed for hot insertion or extraction.
n
Wait five minutes after shutting off the power supply before inserting or removing a ConverterPAC or
to clear on OVP fault condition.
n
NOT
restrict airflow to or from the supply as this can cause overheating damage.
DO
n
Booster ConverterPACs are available for power expansion. Refer to Page 6 for additional information.
n
not use boosters as independent outputs. Operating boosters with disconnected bus bars will
Do
cause failures.
n
Before turning on the unit, ensure all input and output wires are properly connected and all hex nuts
properly tightened.
n
Keep output wires as short as possible and run the output (+/–) power cables next to
each other. Use twisted-pair wiring whenever possible.
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n
AVOID
running input and output wiring in close proximity, as this may cause noise-related problems.
n
MegaPACs are
NOT
user serviceable. Please contact our customer service department at
PFC
1-800-735-6200 for repair assistance. Please be advised that attempts to repair or modify the power
supply will void the warranty.
n
proper fault protection device (fuse or breaker) should be used in series with the input terminals.
A
n
proper size wires to avoid overheating and excessive voltage drop.
Use
n
NEVER
loosen the inner nut on a ConverterPAC™.
n
FinPAC ConverterPACs can only be used with a high-power chassis. A high-power chassis is identified
by an “MX” prefix code in the specific model number.
n
Output voltages over 60V
DC
, whether from individual modules or series arrays, are considered
as hazardous secondary outputs under UL 60950. Appropriate care must be taken in design
implementation of the supply.
Technical Description
The PFC MegaPAC™ chassis consists of an off-line single phase, power-factor-corrected front end, EMI
filter, cooling fan, 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 “B” 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 Vicor’s 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 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
2s 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.
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.
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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™ and
PFC MegaPAC
high-power architecture
Input
Line Filter
Rectifier
Waveform
Sample
Current
Sample
Soft Start
Circuit
Boost Converter
High Voltage
DC Bus
ConverterPAC #1
Power
Output
ConverterPAC #2
PFC Control
ConverterPAC #3
Power
Output
Power
Output
Customer
Interface
E/D Control
Enable/Disable Control
Fan
Current
Monitor
Housekeeping
Power
ConverterPAC #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. (Currently, two exceptions are the FinPACs™ which can only be used in the high-power chassis
and the UniPACs™ which can only be used in the 4kW MegaPAC.) For outputs greater than 200W, a
driver ModuPAC and one or more booster ConverterPACs will be used. For outputs greater than
600W, a driver FinPAC 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.
Installing ConverterPACs as Drivers
ConverterPACs can be installed in empty slots by simply sliding in the new ConverterPAC and securing
the screw at the base. Torque the retaining screw to 0.23N.m (2lb.in); do not overtighten. Power and
interface connections can be made after the ConverterPAC has been installed.
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