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UG:108 

vicorpower.com  

Applications Engineering: 800 927.9474 

Page 25

Current Share Boards  - Optional Feature

"Current sharing" also known as Load Sharing, is the ability to divide the output current 
evenly across all active power supplies. This greatly reduces stresses on each power 
supply and allows them to run cooler, resulting in higher reliability. Standard "current 
sharing" techniques typically utilize shunt resistors or Hall Effect devices to measure 
the current from each power supply. Power shunt resistors continually dissipate power 
and require cooling especially when dealing with high output currents of >100 Amps.  
Hall Effect devices measure magnetic fields generated by current flowing through a 
conductor and, although they dissipate no power, they tend to be large and expensive.
First developed by Westcor Engineering for paralleling MegaPAC supplies, the Box-to-
Box Current Share Board or CSB allows two or more Vicor power supplies to current 
share by utilizing the inherent voltage drop produced in the negative output return 
cable. This eliminates the need for additional shunt resistors or expensive Hall Effect 
devices and provides a simple 5 wire connection method to achieve a +/-1mV accuracy 
between the Negative Output power rails. This accuracy translates to a 1% current 
sharing if there is a total of 100mV conductional voltage drop in the negative    
return path.
Constructed as a current source to drive the Trim pin of a Vicor module, the design 
uses an accurate comparator circuit to monitor the power returns. In addition, the 
circuit is unidirectional and can only trim an output voltage up. The benefit is that 
only the supply that is supporting less current is adjusted up. This action balances the 
currents to the load by matching the output voltages of the supplies. In the case of one 
supply failing, the circuit will attempt to trim the failed supply only. This will leave the 
remaining functional supply alone to provide power to the load at its nominal voltage.  
Thus the circuit also offers simple redundancy. In addition, because CSB functions as 
a current source, the Trim outputs (T1 and T2) of the CSB can be placed in parallel to 
create a summing node. This allows current sharing between more than two supplies by 
paralleling the T2 output of one CSB circuit with the T1 output of the next CSB.

Environmental Characteristics

Storage Temperature

-40°C to 85°C

Operating Temperature**

-20°C to +45°C full power, -20°C to +65°C half power

Humidity

0 to 95%  non-condensing

Altitude

Derate 2.6% total output power for each 1,000 ft to a maximum operating 
altitude of 15,000 ft.  Non-operating storage maximum altitude is 40K.

Safety Approvals

cURus  – UL 60950-1, CSA 60950-1
cTUVus –  EN 60950-1, UL 60950-1, CSA 60950-1
CE Mark – Low Voltage Directive, 73/23/EEC amended by 93/68/EEC

Product Weights

3 Phase MegaPAC - EL

: 21.6 lbs (9.8 kg) fully configured

4 kW MegaPAC

: 22 lbs. (10 kg) fully configured

Warranty

2 years limited warranty. 
See 

vicorpower.com

 for complete warranty statement.

*  See Vicor module specifications. A preload may be necessary for modules trimmed down below  

 

 

90% of normal output voltage.

**  Operating temperature is 45°C using any combination of modules and output voltages as long as
 

the front end rating is not exceeded. Normal derating applies to half power if the ambient  

 

 

temperature is 20°C hotter.

Specifications (Cont.)

Summary of Contents for 3 Phase MegaPAC-ELTM

Page 1: ...ilding blocks For detailed information about all ConverterPACs refer to the ConverterPAC information sheets The 4kW MegaPAC EL Low Noise uses VI 200 VI J00 and Maxi Vicor DC to DC converters while the 3 Phase MegaPAC EL Low Noise uses VI 200 VI J00 Vicor DC to DC converters Manufactured at Westcor a division of Vicor the entire family of MegaPAC power supplies is completely user configurable If ou...

Page 2: ...ent range with built in potentiometer n Reversed fan airflow direction n Current Share Boards see page 25 Mechanical Considerations The 3 Phase MegaPAC EL and 4kW MegaPAC EL 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 ...

Page 3: ...it Leave 2 inch minimum space in front and behind the supply The cooling fan draws air into the unit and forces it out at the output power terminals n For power expansion use booster ConverterPACs Viewing the unit from the output terminal side always insert boosters to the right side of the driver n Do not use boosters as independent outputs Disconnecting bus bars will damage booster ConverterPACs...

Page 4: ...occurs when the peak input current reaches 30 A An analog temperature monitor is provided as well as overtemperature shutdown An active high TTL compatible Enable control is included for each ConverterPAC assembly as well as an active low General Shutdown control the polarities active high or active low are factory set Two or more 3 Phase MegaPAC ELs can be safely paralleled with accurate current ...

Page 5: ...rterPACs can be installed in empty slots by simply sliding in the new ConverterPAC and securing the screw at the base Power and interface connections can be made after the ConverterPAC has been installed Installing Booster ConverterPACs to Increase Output Power Most ConverterPACs of the same length can be paralleled for more power Additional power to an output is obtained by connecting one or more...

Page 6: ...e and common mode noise filters on the output reduce ripple under any load condition to 10 mV p p or 0 15 whichever is greater QPACs can only be ordered in the extended length Low Noise MegaPAC products Please note that for all QPACs the output voltage from either output terminal to chassis should not exceed 400 Volts DC or peak DualQPAC LD The DualQPAC output assembly consists of two VI J00 Vicor...

Page 7: ... Std Std Std Opt Opt Opt DualQPAC LD N A Std N A AS AS Std N A Junior QPAC LJ N A Std N A AS AS Opt Opt See page 12 and 16 for more information on Autosense Currently the QPAC XQ can only be used in the 4kW MegaPAC EL OVP Overvoltage Protection latching OCP Overcurrent Protection auto recovery OTL Overtemperature Limiting latching RS Remote Sense PG Power Good DC OK TTL Signal LS Local Sense AS Au...

Page 8: ...N1 TRIM 4 5 SENSE 7 6 OUTPUT ADJUST P2 REMOTE SENSE TRIM SC POWER GOOD VOUT V0UT J1 B PIN1 OUTPUT CONNECTORS 1 AND 4 V OUT 3 3 R SENSE 6 R SENSE 1 2 J1 A TERMINALS MOLEX P N 39 00 0039 HOUSING MOLEX P N 39 01 2060 CRIMP TOOL MOLEX P N 11 01 0197 MATING HDWR 6 5 4 2 AND 5 V OUT DUAL QPAC POWER GOOD INVERTED N C SIGNAL GROUND POWER GOOD Vcc IN TRIM TOP J1 A PIN1 3 R SENSE 6 R SENSE 6 5 4 J1 B 2 AND ...

Page 9: ...aPAC chassis xB number of modules xxx assigned by Westcor xG Optional Code 2 VI J00 or VI 200 module in slot 1 3 Maxi in Slot 1 xH Optional Code 2 VI J00 or VI 200 module in slot 10 3 Maxi in Slot 10 EL Indicates extended length chassis for use with QPACs If a Maxi module is used the part number changes from MP to MX ConverterPAC XxDV xEAxF eg L15V 10A eg L15V 10ADFIL eg LD15V 6 7A 12V 8 3AT X Con...

Page 10: ...t T6 100 110 output adjustment F9 100 110 output adjustment V1 VXI lownoise 150mVorless for 24Voutputs5 I Industrial Grade module V2 VXI lownoise 50mVorless foroutputs 24V K Custom SRF module used V3 1 ripple for outputs 24 V 1 D option Optional for all ConverterPACs EXCEPT the DualPAC BatPAC 2 F option Optional for all ConverterPACs EXCEPT the BatPAC and DualQPAC 3 R option When using an external...

Page 11: ...red for safety reasons Output Connections Power Connections Installing ring lugs and or bus bars on output studs n The upper stud is Positive and the lower stud is the Return n Remove outer nut Do not remove or loosen inner nut n Place ring lug over output stud n Replace and tighten outer nut to a maximum torque of 45 lb in Do Not Over Tighten Nuts n Verify all output nuts are properly installed b...

Page 12: ... applying input power Sense Connections on DualQPACs n Sense connections do not have to be made if the Local Sense option has been ordered An L in the ConverterPAC part number means the Local Sense option has been installed e g D5 V 20 AL 12 V 4 2 AL n Sense connections are available on the P2 connector or the J1A and J1B connectors Either can be used n Using J1A J1B pin 3 is the Sense and pin 6 i...

Page 13: ...terminals to 22 28 AWG twisted pair wire using Molex tool 57005 5000 Interface Connections J10 n J10 7 to 11 and J10 20 to 24 are Enable Disable for slots 1 10 n J10 16 17 are Vcc J10 12 and 15 are Signal Ground J10 18 is AC Power OK and J10 5 is General Shutdown POWER GOOD INVERTED N C 5 3 2 4 1 SIGNAL GROUND POWER GOOD Vcc IN 7 6 TRIM TOP J2 PIN1 TRIM BOT Trim Pin Connector for DualQPAC SENSE PO...

Page 14: ...X 1 2 SLOTS 10 2 MM 40 46 11 7 MM 1 900 1 5 A 4 7 4 4 0 H Z 2 0 8 2 4 0 V A C 3 ÿ LABEL LOCATED APPROXIMATELY QPAC MODEL NO AS SHOWN TYP STANDARD AIR FLOW 3n MegaPAC WESTCOR AS SHOWN QPAC REMOVAL APPROXIMATELY LABEL LOCATED SERRATED FLANGED NUTS 1 4 20 PLATED STEEL 45 lbf in BOTTOM VIEW 1 20 5 10 3 5 MM 129 5 MM 190 5 MM 12X 8 32 PEMNUT 15 MAX PENETRATION 150 3 8 MM 7 50 57 2 MM 57 2 MM 2 25 11 95...

Page 15: ... 10 2 MM 40 46 11 7 MM 1 900 1 5 A 4 7 4 4 0 H Z 2 0 8 2 4 0 V A C 3 ÿ LABEL LOCATED APPROXIMATELY 4kW MegaPAC WESTCOR AS SHOWN QPAC REMOVAL QPAC MODEL NO AS SHOWN TYP APPROXIMATELY LABEL LOCATED SERRATED FLANGED NUTS 1 4 20 PLATED STEEL 45 lbf in BOTTOM VIEW 1 20 5 10 3 5 MM 129 5 MM 190 5 MM 12X 8 32 PEMNUT 15 MAX PENETRATION STANDARD AIR FLOW 7 50 57 2 MM 57 2 MM 2 25 11 95 303 5 MM 12 28 311 2...

Page 16: ...it levels Avoid large current loops in output cables run power and return cables next to one another to minimize inductive effects All outputs are isolated and can provide positive or negative outputs Output Sense Connections P2 for Single Output or J1A J1B for Dual Outputs Newer power supplies may have some outputs configured with the Autosense feature that automatically locally senses the output...

Page 17: ...led low to less than 0 7 V The GSD control line is configured to be active low with internal pull up all outputs are simultaneously inhibited when the GSD control line is pulled low to less than 0 7 V All outputs are enabled when GSD is open circuited or allowed to exceed 4 5 V The polarity of both the ED and GSD lines as well as pullup or pull down can be reversed as a factory option per below di...

Page 18: ... 6 In order to disable this array E Ds 1 through 6 should be shorted together as shown in Fig 6 With the E Ds connected together a single switch can then be used to remotely enable and disable the output Note Note For single output power supply configurations the simplest method of remotely enabling and disabling the output is to use the General Shutdown GSD function Figure 6 Enable Disable Contro...

Page 19: ...30 A due to the loss of an input phase or severe line imbalance This occurs when one input phase is lost with approximately 1 400 W output loading Maximum current that can be sourced is 10 mA Overtemperature Warning J10 3 J10 3 is a signal that asserts a TTL level 1 if the air temperature exceeds the following factory set levels The warning trip point is 65 C to 76 C typically and recovery point i...

Page 20: ... 1 and slot 10 were configured for use with VI 200 QPAC L or Maxi QPAC XQ DC to DC converters Using the example of MX7 410108 32 the last two digits 32 identify the type of module in slot 1 and slot 10 respectively A 3 indicates the chassis is configured to parallel box to box using a Maxi converter A 2 indicates the chassis is configured to parallel box to box using a VI 200 converter The above e...

Page 21: ...erence point for the Power Good circuitry and is not the same as Earth Ground on input power connector J1 Vcc In P2 4 The Vcc In on P2 4 is an input that requires 5 V either from the J10 Auxiliary Vcc or from another source Input current to this pin is limited by an internal resistor to 3 mA If the J10 Auxiliary Vcc is connected to Vcc In on P2 4 then at least one J10 Signal Ground must be connect...

Page 22: ... above the nominal converter voltage and 50 below the nominal converter voltage as measured from the output studs or output connector of the power supply Note The combined effects of module trim up remote sense and dynamic load step may cause the module to trip OVP Recovering from OVP will require cycling input power to the MegaPAC The Trim pin on P2 can be used to control the output voltage It is...

Page 23: ... the bottom limit VR6 2 5 V 10 2 25 V And since IR5 IR6 25 mA R6 VR6 IR6 2 25 V 25 mA 90 kW V2 V1 VR6 2 75 V 2 25 V 5 V IR7 V2 R7 5 V 10 kW 500 mA IR8 IR7 IR6 525 mA VR8 Vnom 10 V2 13 2 V 5 V 8 2 V Given Vnom 12 V R8 VR8 IR8 8 2 V 525 mA 15 62 kW Using the above resistor combination a 12 V output can be trimmed externally up to 13 2 V and down to 10 8 V For further information on external trimming...

Page 24: ...ulation 0 20 max to 0 30 max Maxi Load Regulation 0 20 max to 0 70 max VI 200 VI J00 Setpoint Accuracy 1 for standard voltages 2 for special or adjustable voltages Maxi Setpoint Accuracy 1 for standard voltages 2 for special adjustable voltages and 48 V outputs Ripple and Noise QPAC DualQPAC JrQPAC 10 mV p p max or 0 15 whichever is greater QPAC XQ 10 mV p p max or 0 15 whichever is greater Output...

Page 25: ...tional and can only trim an output voltage up The benefit is that only the supply that is supporting less current is adjusted up This action balances the currents to the load by matching the output voltages of the supplies In the case of one supply failing the circuit will attempt to trim the failed supply only This will leave the remaining functional supply alone to provide power to the load at i...

Page 26: ... to 100 mV of drop will provide from 5 to 1 accuracy 3 V1 and V2 for all Box to Box circuits must be connected directly at the negative output power studs or terminals to achieve accurate current sharing 4 D can be added if redundancy is needed If redundancy is not required D can be replaced with direct wire connections 5 When using D the Power input should be connected on the cathode side of the ...

Page 27: ...be used for current sharing Maxi converters Please note The CSB is NOT intended for Hotswap Applications Contact your Regional Applications Engineer at 1 800 927 9474 for additional information Figure 14 Cable Drawing P1 24 0 1 0 Power T1 V1 T2 V2 Red 22 AWG Yellow 22 AWG Brown 22 AWG White 22 AWG Black 22 AWG 1 2 3 4 5 6 1 74 44 2mm 0 12 3 0mm 1 500 38 1mm 0 12 3 0mm 0 900 22 9mm 1 14 29 0mm 0 13...

Page 28: ...ained with the removal of the Y capacitors from within the EMI filter of the MegaPAC as well as the Y capacitors on the input of the ConverterPACs This reduces the leakage current from the AC input to AC ground chassis to below 500mA At the same time since the Y capacitors are a vital component of the EMI filter without them the EMI will go up When this happens the unit will no longer meet Westcor...

Page 29: ...UG 108 vicorpower com Applications Engineering 800 927 9474 Page 29 NOTES ...

Page 30: ...FC Micro PFC Mini MEGAPAC FAMILY PFC MegaPAC 4kW MegaPAC 4kW MegaPAC EL Low Noise PFC MegaPAC High Power PFC MegaPAC Low Noise High Power PFC MegaPAC EL Low Noise Mini MegaPAC Autoranging MegaPAC ConverterPACs OTHERS FlatPAC EN PFC FrontEnd MicroPAC Conduction Cooled MicroPAC Rugged COTS versions MI are available for the PFC Micro PFC MicroS PFC Mini and PFC MegaPAC Information furnished by Vicor ...

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