Fluke 415B Instruction Manual page 43

415B
NOTE!
The
unit
must have been operated
for
one
hour
before
testing to
the following requirements.
The
cover
must
be
in
place during the ripple
test.
NOTE!
Meter
readings
will
vary with contact
resistance.
Make
comparative readings with load
on
Front
and
rear
output
terminals.
4-23.
OUTPUT AT ZERO
VOLTS.
This
test
checks
for
imbalance
in the
voltage control
circuit.
a.
Set the controls
of the
Model 415B
as
follows:
POWER
ON
HIGH
VOLTAGE STDBY/RESET
POLARITY
Negative
OUTPUT VOLTAGE
All
zeros
dials
b.
Connect
the
Model 885A across
the
OUTPUT
con-
nector.
c.
Set the
HIGH
VOLTAGE
switch
to
ON. The Model
885A
at null
should
indicate no
more
than 50 milli-
volts for both polarities.
4-24.
LINE
REGULATION.
This
test
determines
whether
the deviation
in
output
is
within specified limits
for
a
change
from
low
to
high
line
voltage.
a.
Set the controls
of the
Model
41
5B
as
follows:
POWER
ON
HIGH
VOLTAGE
STDBY/RESET
POLARITY
Positive
OUTPUT VOLTAGE
Second
dial to 500;
dials
all
others
to
zero
b.
Connect
the
Mode! 885A
across the front panel
OUT-
PUT
connector.
c.
Adjust
the
autotransformer
for
103
volts output.
d.
Set
the
HIGH
VOLTAGE
switch
to
ON.
Adjust the
Model
885A for a
null indication.
e.
Connect
a
16.7K
ohm
resistor across the
rear panel
OUTPUT
connector. The
voltage
change
indicated by
the
Model 885A
shall
be
less
than 2.0
millivolts.
a.
Set the controls
of
the
Model 415B
as
follows: NOTE!
POWER
ON
POLARITY
Positive
OUTPUT VOLTAGE
Second
dial to
500;
dials
all
others
to zero.
b.
Adjust the autotransformer
for 103 volts output.
Adjust the
Model 885A
for
a null indication.
c.
Increase the
line
voltage
to
127
volts.
The
output
voltage change indicated by
the
Model 885A
shall
be less than
3
millivolts
(6
ppm).
d.
Set the
HIGH VOLTAGE
switch to
STDBY/RESET
and disconnect
the
Model 885A from
the
OUTPUT
connector.
Meter
readings
will
vary with
contact
resistance.
Make
comparative
readings with
load
on
front
and
back output
terminals.
f.
Disconnect the load resistor
and see the
POLARITY
switch
to
negative.
g.
Repeat
the
measurements
of steps
d and
e,
4-26.
RIPPLE.
This
test determines whether
the-
residual ac component superimposed
on
the dc output
is
within specified limits. Ripple
is
usually higher
with negative polarity output. Proceed
as
follows:
a.
Set
the controls
of
the
Model
41 5B as
follows:
e.
Set the
autotransformer
output
to
103
volts.
Set
the first
OUTPUT VOLTAGE
dial to 2500, the
second
dial to
500 and
all
others
to
zero.
f.
Connect
the output
terminals
of the
Model
80F-5
voltage divider to the input
of
the
Model 885A and
connect the divider input across
the
Model 415B
OUTPUT
connector.
g.
Set the
HIGH
VOLTAGE
switch
to
ON
and
adjust
the
Model 885A
for
null indication.
h.
Increase the
line voltage
to
127
volts.
The
voltage
change indicated by
the
Model 885A
should be no
more
than
1.
8 millivolts
(6
ppm)
at the 10:1
divider
output.
4-25.
LOAD REGULATION.
This
test
determines
whether
the
output deviation
is
within
specified limits
for
a load change from no
load
to full
load. Before perform-
ing the Load
Regulation
Test, verify current,
limit
trip
point
is
30
milliamps
or greater. If
it is
not, adjust
it
according
to
the procedure
in
paragraph
4-33.
POWER
HIGH
VOLTAGE
POLARITY
OUTPUT VOLTAGE
dials
ON
STDBY/RESET
Negative
Second
dial to 500;
all
others
to
zero
b.
Connect
the
5,000 volt blocking capacitor and
the
protection circuit
shown
in
Figure 4-2 between
the
OUTPUT
connector and
the inputs to the
Model
93
IB
RMS
voltmeter and the oscilloscope. This
circuit
protects the input circuitry
of
the oscilloscope and
the voltmeter
from a 3000
volt
charge on
the
block-
ing capacitor
if
the
Model 415B output
is
accidently
shorted.
0.05 uf or larger
5000
VDC
ffoCQ
2W
«
it
'
0
1 |
w
°
TO
POWER
SUPPLY 1
1
I
I
OSCILLOSCOPE
OUTPUT
0
!
tfl
1
MQ
IV/
j
AND
RMS
METER
INPUTS
DIODES: Type
1N4817
(JF
P/N 4802-116111) or
equivalent.
Figure
4-2.
PROTECTION
CIRCUIT
Rev. 2 4-3