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Alternative
AC
Current
Verification
(100|iA-l
A
Full
Range
Values)
Appendix
5
to:
4708
User's
Handbook
Section
7
Summary
of
Verification
Procedures
Full
Range
Current
(Using
Calibrated
Standard
Shunts)
The
procedure
is
carried
out
first
at
LF
(300Hz),
then
at
HF
(5kHz)
for
each range
in turn,
using
the appropriate
standard
current shunt.
An
AC
DMM
is
standardized
to the verified
and
corrected
IV
Full
Range
output of
the
4708,
via
a
unity-gain
buffer.
The 4708
is
set to
output a
Full
Range
current
into
the
calibrated
AC
Current Shunt
at
the required frequency.
The
current
output develops a voltage across
the
shunt
which
is
measured by
the
standardized
DMM,
using
the
same
buffer
to
avoid loading
the
shunt.
After accounting
for
the setup
uncertainties, the
measured
current
is
compared
against the specification
limits.
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
set
of
calibrated
AC
Current Shunts of
suitable
value
and
accuracy.
•
A
buffer with unity gain
verified at
300Hz
and 5kHz.
•
A
DMM
of
suitable
accuracy.
Example: Datron 1281
or 1081,
in
'Compute'
Mode.
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
is
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
cany
out
the
test
routine
described
in
Section
4.
Terminate
the
test
routine.
5
.
If
'Spec'
Mode
is
required, select either 24hr,
90dy
or
lyr
on
the
Rear
Panel
CALIBRATION INTERVAL
Switch.
When
received
from
Datron,
90dy
is
the
relevant
selection.
The
report sheets
hold
figures for
this interval.
7-A5-1
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