BK-130
7-2
CALIBRATION
3.
Overcurrent
This calibration should not need adjustment (factory adjusted). If the Overcurrent Circuit is out of
calibration, perform the following steps. To recalibrate the Overcurrent Circuit with the High Voltage Unit it
will be necessary to connect a 15
– 20 nanofarad capacitor rated at 36 kVAC or higher to the 36 kV / 180
mA output of the High Voltage Unit. If the capacitor is isolated from ground at the low potential end, the
low potential end can be connected to the RTN post. The Guard Post Jumper may be connected to GRD
(Guard Mode). If the low potential end of the capacitor is grounded, the Ground Post Jumper must be
connected to RTN post.
a.
Set front panel Measurement Divider switch to 36 kV/180 mA. When current trip dial is set to
minimum (1) current trip level should be approx. 18mA. When dial is set to maximum (11) trip
level should be approx. 198mA.
b.
Set the Overload Trip potentiometer (R15) on the front panel to "1" and the Current Range
switch to 200 mA.
c.
Turn on HV On and adjust the output current slowly until 10% of rated current
is displayed on the current meter. (18 mA)
d.
Adjust potentiometer R101 until the Reset lamp illuminates and
high voltage is shut off.
e.
Set the Overcurrent Trip potentiometer (R15) on the front panel to "11".
f.
Turn on HV On and adjust the output current slowly until 110% of rated current is
displayed on meter.
g.
Adjust potentiometer R103 until the Reset Lamp illuminates and
high voltage is shut off.
h.
Repeat steps "b" through "g" if necessary until both settings are calibrated.
4.
Range Overcurrent.
R235 sets an overcurrent for the ranges and should be set to trip at approximately
112% of full range current on medium range setting with current trip potentiometer set at “11.”.
