CSPP Capacitor Charging Unit Operation Manual
CSP-CSPP-8000/2
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Page
27
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59
High Voltage Section
The right side of the unit contains the high voltage parts. Each capacitor is switched in
and out of circuit by 12 kV rated, spring relays. The relays use a rotating moving contact
which is silver plated. The fixed contacts can be rotated in the event of wear. When
disconnected, the capacitors are discharged through the relays to ground via 10k
resistors, which are mounted on a circuit board on the RH panel. Although physically
small, these resistors can handle 2000J pulses at well in excess of the rated voltage of the
unit. It should be noted that the average power these resistors can tolerate is 6 watts.
Repeated discharge of the capacitors into these components will cause them to fail.
A specially designed high current thyristor switch is used in the CSP-P , interfaced to the
control board by an interface board. This is held in place with an isolated clamp
arrangement manufactured from Nylon 66.
Note: All models operate at approx 4KV.
HV Monitor Board
Using a current sensor the HV monitor circuitry monitors the output current to prevent
excessive load currents damaging components. The circuitry also monitors the HV voltage
to detect open circuit load conditions where the energy has not been discharged. Upon
detection of the above faults the board flags a LOAD fault to the control board, this fault is
automatically reset after 10secs in order to warn the operator of a possible fault with the
load thus preventing damage to internal circuitry.
HV Detect Board
This board using a HV resistor voltage divider via opto isolator provides voltage feedback
to the HV Monitor board on the charge status of the capacitors to detect an open circuit
faut condition. The board also contains diodes to protect the output bridge of the charger
from reverse voltage swing. There is also a set of high current diodes which are used to
limit the amount of reverse voltage swing on the output of the unit.
Thyristor Interface Board
This board provides an interface between the control board and the thyristor by providing
an isolated 5V supply and switching the 12V CMOS trigger pulse down to 5V TTL.
