High Voltage Control Unit Typ HST 01/01 - SCHNIER Elektrostatik ...

5.2 Constant
Current Mode
Operating Manual
Nr. 810123BE_02/00
Page 13 of 17
In the constant voltage mode the static current disconnection
treshold can be adjusted between 0 and approx. 820 µA. When
reaching approx. 80% of the adjusted disconnection treshold the
"warning" signal is generated. As soon as the load decreases,
the signal disappears. If the load nevertheless increases the
controller indicates "fault" when the adjusted treshold value is
reached. High voltage then will automatically be switched off. In
order to switch the high voltage on again, the "HV on" signal has
to be surpressed during at least one second either by (12) on the
front plate or by means of the external control system.
The dynamic di/dt disconnection treshold can be adjusted
between 0 and approx. 999 µA/s. This part of the controller
continuously monitors in which time a determined current value
is reached, either during current rise or fall (current slope
steepness). If the current slope is steeper than permitted by the
adjusted value, the controller will indicate "fault". The fault reset
procedure is the same as for static disconnection. The dynamic
disconnection is independent of the static disconnection treshold.
This means that a dynamic disconnection may also be triggered
if the current is significantly below the static disconnection value.
On the front plate of the HV control unit the type of disconnection,
either static of dynamic, will be displayed. In addition a collective
fault is output to the external control system.
In constant current mode the operating current can be adjusted.
This value is kept constant by regulating the output voltage. When
reaching approx. 80% of the adjusted current value the "release"
signal is output. By means of the "kV" nominal value the maximum
admissible operating voltage between 40 and 100 kV can be
limited.
In constant current mode the static voltage disconnection treshold
is fixed to approx. 38 kV. When reaching this value the device
switches off and indicates "fault". In order to switch the high voltage
on again, the "HV on" signal has to be surpressed during at least
one second either by the switch (12) on the front plate or by means
of the external control system. Before the controller disconnects
the "warning" signal is generated at appox. 46 kV.