Datron 4708 User Handbook Manual page 79

DC
Voltage
Verification
(lOO^iV-lOOOV
Full
Range
Values;
lOV Range
Linearity)
Summary
of Verification
Procedures
1
.
Full
Range
Low
Voltage
(lOO^iV
-
10V Ranges)
The
4708, a Null
Detector
and
a
DC
Voltage Standard
are
connected up and
the
4708
is set to
output a Full
Range
voltage.
The
DC
Standard
is
adjusted
to null
with the
4708
Full
Range
voltage,
and
its
output
voltage
is
recorded.
The
accumulated uncertainties are
also recorded,
and
the Validity
Tolerance Limits are
calculated.
The 4708
is
verified
if
the
DC
voltage
is
within
the tolerance limits.
Details
of
the
procedure
are
on pages
7-4/5.
2.
Linearity
(Performed
on 10V Range)
Should be checked
at
±0V,
±10V
and
±19V
in turn.
Similar techniques
are
used as for Full
Range
voltages.
For each check
the
results
are recorded.
Details
of
the
procedure
are
on pages
7-4/5.
3.
Full
Range
High Voltage
(100V
&
1000V Ranges)
The
4708, a Precision Divider, a Null Detector
and
a
DC
Voltage Standard
are
connected
up and
the
4708
is
set to
output a Full
Range
voltage.
The
DC
Standard
is
adjusted to null
with
the
4708
Full
Range
voltage,
and
its
output voltage
is
recorded.
The
accumulated
uncertainties are also recorded,
and
the Validity
Tolerance Limits
are calculated.
The 4708
is
verified
if
the
DC
voltage
is
within the tolerance
limits.
Details of the procedure are
on pages
7-6/7.
Interconnections
Interconnection
instructions in this
section are necessarily
simple and
basic,
and
are
mainly
intended
to
show
connec-
tions
to
the 4708.
It is
recognized
that
they
may
need
to
be
adapted
to
meet
an individual
user's
requirements.
It
is
assumed
that users will
possess
knowledge
of
the
operation
and use of standards equipment such
as that
mentioned above.
Equipment Requirements
•
A
Standard
DC
Voltage Source of
suitable
accuracy.
Example:
Series
bank of 10 standard
cells
and
Datron
4904
Standard
Cell Buffer.
•
A
Precision Voltage Divider.
Example: Datron
4902 High
Voltage
Divider.
•
A
battery-operated
Null Detector with variable
sensitivity,
able
to
withstand
1200V
across
its
input
terminals.
Example:
Keithley Instruments
Model
155.
N
.
B
.
Either the
DC
source or Precision Voltage Divider
should be of a type
which
permits verification
at
Nominal
Full
Range
values,
and 19V.
Preparation
Before attempting
any
verification
ensure
that
the
follow-
ing steps
have been
carried
out.
1
.
Turn on
the instrument
to
be checked and allow
at least
2
hours
warm-up
in
the specified
environment.
2.
Cancel any
MODE
keys, ensure
OUTPUT
OFF
and
check
that
'cal' is
not present
on
the
MODE
display.
(If
'cal'
is
present, turn the Calibration
Keyswitch on
the
Rear
Panel
to its
RUN
position).
3
.
Before connecting and
operating
any equipment,
consult the manufacturers'
handbooks.
4.
Self-Test: Press the
'Test'
key
to carry
out
the
test
routine described
in
Section
4.
Terminate
the
test
routine.
5. If 'Spec'
Mode
is
required, select either 24hr,
90day
or
lyr
on
the
Rear
Panel
CALIBRATION INTERVAL
Switch.
When
received
from Datron, 90day
is
the
relevant
selection.
The
report sheets
hold
figures for
this interval.
7-2