Spellman ST SERIES Instruction Manual Download

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ST/STR/STA MANUAL

118107-001 REV J

Typically a SYSTEM FAULT and AC FAULT indication
will appear on the front panel if an error in the charging
circuits has occurred.

R5  on  the  POWER  PWB  –  A6  functions  as  a  bleeder
resistor,  which  is  used  to  discharge  the  front  end  filter
capacitors  C1  and  C2.  DS1  provides  visual  indication
when DC voltage is present.  This indicator should not be
relied  on  for  confirming  the  presence  or  absence  of  the
DC  voltage  in  any  situation  where  user  safety  is  of
concern.

4.2 Inverter

The inverter employs a proprietary, quasi-resonant, pulse
width  modulated  topology.  L1  and  L5  are  the  resonating
inductors.  Q1,  Q2  Q3  and  Q4  are  high  speed  IGBT
isolated  power  modules.  These  devices  provide  high
frequency  switching  capability  to  control  the  flow  of
current  through  the  primary  of  the  high  voltage  step  up
transformers.    The  gate  control  for  the  switching  devices
is  provided  by  GATE  DRIVE  PWB  A3  and  A4.  The
control signals are generated by the SYSTEM CONTROL
PWB – A1.

4.3 High Voltage Transformer

The output of the Inverter is  connected to the primary of
the  High  Voltage  Transformer.  The  High  Voltage
Transformer  is  a  step-up  type.    Typical  secondary
voltages are in the range of 1kV to 4.5kV depending upon
the units specific maximum output voltage rating.

4.4 High Voltage Assembly

The  High  Voltage  Assembly  will  vary  depending  upon
the  model  ordered.    The  circuitry  typically  consists  of  a
full  wave,  full  bridge,  or  full  wave  doubler  for  voltage
outputs in the range of 1kV to 10kV.  The higher voltage
ranges  utilize  various  parallel,  series  arrangements  of  a
full  wave  voltage  doubler.    For  example,  the  8kV  output
is  obtained  by  connecting  a  number  of  full  wave  voltage
doublers  in  parallel.    The  120kV  output  is  obtained  by

connecting a number of full wave voltage doublers in
series.

Output  filtering  is  typically  provided  by  an  L-C  type
filter.  Voltage feedback  for regulation and  monitoring is
provided  by  a  high  bandwidth  resistive/capacitive
compensated  feedback  divider.    Current  feedback  for
regulation and  monitoring  is  provided by a sense resistor
connected  at  the  low  voltage  end  of  the  High  Voltage
output section.

4.5 System Control PWB

The majority of control circuits for power supply controls
are located on the SYSTEM CONTROL PWB – A1.  For
trouble  shooting  and  testing  purposes,  this  board  can  be
easily  accessed  by  removing  the  screws  located  on  the
side  panels  near  the  front  panel.  The  front  panel  will
hinge  down  allowing  for  easy  access  to  the  SYSTEM
CONTROL PWB

4.6 Front Panel Assembly

Front Panel CONTROL POWER, HV OFF, HIGH
VOLTAGE

ON,

switches,

voltage

and

current

programming  potentiometers,  voltage  and  current  digital
meters,  and  status  indications  are  connected  to  the
FRONT PANEL PWB. – A7. The FRONT PANEL PWB
interfaces  directly  to  the  SYSTEM  CONTROL  PWB  -
A1.

4.7 Master/Slave Rear Panel
PWB

– ST Only

This  assembly  is  only  required  and  installed  when  more
than  one  ST  chassis  is  configured  in  the  system.  By
configuring  chassis  in  parallel  using  a  Master/Slave
arrangements additional power increments of 12kW’s can
be  obtained  for  each  chassis  added.  This  Master/Slave
Rear  Panel  PWB  provided  the  necessary  control  signal
connectivity and functionality to operate multiple chassis
in parallel as a single high powered system.