The TRD High Voltage Distribution Box MasterSlave System Progress Report

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The TRD High Voltage Distribution
BoxMaster/Slave System Progress Report

• Athens University
• A. Petridis
• M. Potirakis
• M. Tsilis
• M. Vassiliou

G.S.I 25-26/2/04
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• Requirements
• 1. H.V for the Drift Field (540 channels)
• About -2.1 K.V with an accuracy of about 2-5 V
  (.1 to .2)
• Allowed ripple less than 50mV peak to peak
• Stability .1 per 24 hours
• The allowed maximum current 7-10uA
• The accuracy of the current measurement at the
  level of 2nA
• 2. H.V for the Anode Wires (540 channels)
• About 1.7 K.V with an accuracy of about 1-2V
  (.05 to .2)
• Allowed ripple less than 50mV peak to peak
• Stability .1 per 24 hours
• The allowed maximum current 5-7uA
• Accuracy of the current measurement at the level
  of 2nA

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• Solution
• Two Distribution Boxes (for better monitoring ,
  save
• space,
  and cabling money?)
• From a H.V, master system (ISEG,CAEN ), we apply
  90 fixed
• voltages to 90 cards. Each card contains 6
  channels.
• One card provides the appropriate power to a
  single stack
• of the TRD.

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• Trials
• Different approaches were investigated.
• e.g Swiching, low power dissipation but stability
  problems.
• Power supplies in series, carefull design
  since all lines are in high
• voltages.
• Proposed solution
• Shunt Regulator. Easy desigh, but relatively
  high power dissipation
• Lucky the Sanyo to reproduces the 2SC4370LS High
  Voltage Low
• current transistors .
• First measurement showed a good linear behavior.

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• Composition
• Each card contains
• One H.V input provides the ceiling Voltage
  (1700/ -2100V)
• Six High Voltage output channels, provide the
  appropriate Detector
• Voltage to within 1Volt accuracy. eg 1700 DV(in
  a step of 1V)
• One microcontroller of Avr(mega 8) drives
• 6 shunt regulators
• 2 DACs of 3 each ,
• Six single ADCs,
• 2 X 3 ADCs
• Six Swiches for swiching off the power of the
  detector.
• One input Reed Relay and
• One CanBus driver.
• 30 DC signal transformers .

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Each channel contains One Shunt regulator , one
12bit DAC, one 24Bit ADC plus one14Bit


ADC 5 DC signal transformers 11 One shunt
resistor of 0.01 accuracy and 3ppm/C
stability One voltage divider 1400 .05!
accuracy and 15ppm/C stability Low current low
noise Instrumentation amplifiers One comparator
and one error amplifiers One 2SC4730LS low
current transistor withstanding 2100 Volt. One
transistor switch. The resistors are accurate to
a level of .1
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Isolated Shunt Regulators
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Non-Isolated Auxiliary Power Supply
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Two Auxiliary P/S for the isolated channels
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Current monitoring of first channel
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Another version for the current monitoring
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Voltage monitoring
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Microcontroller communication with the ADCs
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Digital Signal Drivers
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Microcontroller / RS232 Interface
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• Summary
• The prototype card is fully designed .
• Gerber files are ready.
• The size the PCB card is 16cm X 24cm
• The first two PCBs are going to be ready in
  three weeks .
• Tests will be started as soon as the PCBs are
  ready.
• Two different designs for current measurement is
  to be tested.
• Remarks
• Maximum current of the Master System.
  (4mA/channel)
• Input/Output connectors.
• Some space in the back plane of the rack for the
  transformers.
• Temperature variation in the hall.

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Setting up a HV system in PVSS for the TRD
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• PVSS V2.12 is running under Linux on a PC Pentium
  IV 2.4 GHz
• Control software for a HV system is under
  development.
• Continue the development under Linux ?
• Need for i. a Power Supply fully
  equipped
• ii. an IXXAT CAN
  interface card
• iii. a DIM / CAN
  interface (Marc)