Fluke 410B - Output at Zero Volts; Calibration; Reference Current Adjustment; Overcurrent Trip Adjustment

4 10B
f. After an
additional 60
minutes
of
operation,
the
voltage change
indicated by
the
voltmeter/
voltage
divider
should be less
than 0. 5
volt
(0.0Q05
volt
indicated by
the
10V
tap).
4-13. OUTPUT
AT
ZERO
VOLTS
a.
Connect
the
voltmeter
to
the
OUTPUT
connector.
b. Set the
POWER
switch
to
ON.
c.
Set
the
OUTPUT
VOLTAGE
controls to
zero.
d. Set
the HIGH
VOLTAGE
switch
to ON.
e. The
88
1A
should
indicate less
than
0.030
volts in
both
output
polarities.
If
not,
exchange
Q213
and/or
Q214 with
another
transistor of
the
same type
used
else-
where
in the
instrument, so
that the
beta of
the
two
transistors
is more
nearly
equal.
4-14. CALIBRATION
4-15.
The
Model
410B
may
be
calibrated as
often as
necessary.
However,
it is
recommended
that the
refer-
ence
voltage be
checked
every
30 days,
and the
over-
current
limit be
checked every
six
months. As
reference
tube V201 (8
3A
1)
ages,
the
reference
voltage
changes
slightly. It has
been
found
that
some
reference
tubes
are more
stable than
others.
However,
most
reference
tubes
will change
by less
than 0.
1%
for every
100 hours
of
operation
after the
first
hundred
hours. If
the
output
voltage
is
recorded
before the
reference
current is
adjusted,
a more
realistic
calibration
period
can be
determined.
The
equipment
required
for
calibration
is
given in
Figure
4-2.
4-16. REFERENCE
CURRENT
ADJUSTMENT
a.
Connect
the 80E-10
Voltage
Divider
to the
output
of the 410B,
and
connect
the
voltmeter
to the
output
of
the
voltage
divider.
b. Set
the OUTPUT
VOLTAGE
controls
to
9,
900
volts,
using only
the
first two
dials.
c.
Set the
POLARITY
switch
to
negative.
d.
Set the
POWER
switch
to ON.
e.
Set the HIGH
VOLTAGE
switch to ON.
f.
Set
the
differential
voltmeter to
differentially
measure 9,900
volts,
considering the
voltage
divider
ratio.
For example,
using
the 80E-10
Voltage
Divider,
set the
differential
voltmeter
to
measure
9. 9
volts.
WARNING
Use
an
insulated
screwdriver
to
adjust R104.
The
case of
this
resistor
is 85
volts
above
chassis
ground
for
negative
output
polarity,
and may
be as
much as
10,085
volts
above
ground for
positive
output
polarity.
g.
After a
minimum
operating
time of
30
minutes,
adjust R 1 04
for a
null on
the
differential
voltmeter.
Within
24 volts of 9,900
volts is
sufficient
(24
millivolts
with the 80E-10).
This
control
may be
adjusted
through
the access
hole on
the
right,
side panel
near
the
front.
4-17. OVERCURRENT
TRIP
ADJUSTMENT
a.
Connect a
IK
±5%,
2W
resistor to the
OUTPUT
connector.
b.
Set the
OUTPUT
VOLTAGE
controls
to zero.
c.
Set the
POLARITY
switch to
negative.
d. Set
the
POWER
switch
to ON.
e.
Set
the HIGH
VOLTAGE
switch
to ON.
f.
Set
the 410B
for
maximum
current trip
by
turning
R15
1
completely
clockwise.
This
control
may
be ad-
justed
through
the
access
hole on the
left
side
of the
instrument.
g.
Set
the
OUTPUT
VOLTAGE
controls
to
that
output
voltage
which
will
deliver
12
milliamperes
to the
load
resistor.
For
example,
12 volts will
deliver
approxi-
mately
12
milliamperes
to a
IK resistor.
NOTE
If it is
desired to
set the
overcurrent
trip
to
some
value
other
than
12 milliamperes,
then
the
output voltage
in step
g.
should be
chosen to
provide
the
desired trip
current.
h.
Slowly
turn
R151
counter-clockwise
until
the over-
current trip
removes
power
from the
high
voltage
trans-
former.
4-18. METER
CALIBRATION
4-19. The
panel
meter
is
adjusted
at the
factory,
and
will
not
usually
require
attention.
If
adjustment is
necessary,
proceed
as
follows:
a.
Set the
POWER
switch to ON.
b.
Set
the HIGH
VOLTAGE
switch
to ON.
c.
Set the
OUTPUT
VOLTAGE
controls
to
10,
000 volts.
d.
Adjust R150
so
that
meter
deflection
corresponds
to 10KV.
This
resistor
may
be
adjusted
through
the
access
hole on
the
bottom of
the
instrument.
4-4