Electrical Test Instruments MAC-20 User Manual

Electrical
Test
lnstruments
MAC-20
Retrofit
Package
Section
lV
-
Service
lnformation
and
Documentation
Electrical
Test
lnstruments,
lnc.
Page
lV-1
SECTION
IV
SERVICE
INFORMATION
AND
DOCUMENTATIbN
MAINTENANCE
AND
CALIBRATION
OF THE
MAC-20
The
MAC-20
is manufactured
using
solid
state components
that
should not
require
extensive
maintenance.
However, the
accuracy
of the
MAC-20
is critical
to the
testing
of circuit
breakers,
and
is dependent
upon
the
output of
an air-core
current
sensing
coil,
which
could
change
due to
movement
caused
by shock
or
vibration
encountered
in
transporting
the
test set.
Other
factors
which
may affect
calibration
are
contact
resis-
tance
in the control
cable,
unusual
magnetic
fields,
insulation
leakage,
and
aging of
electronic
components
in the
MAC-20.
Therefore,
proper
operation
and calibration
should
be
checked
at
regular
intervals,
and adjusted
if
proper
equipment
is available.
The
inherently
delicate
nature of electronic
circuitry
and
metering
make
it
generally
inadvisable
to leave
the
MAC-20
fastened
into the
breaker
test set
while
it is being
transported,
and
subject
to
shock and
vibration. The
standard
rack-mount
hardware
and
twist-lock
connector
make
it simple
to remove
the
MAC-20
and
carry
it
separately.
Suggested
periodic
maintenance
consists
of
the
following:
1. Clean
the
lenses
of the
LED displays
with a
plastic
cleaner.
2.
Clean
the
front
panel
with a soft
brush and
cloth.
3.
Perform
basic
field
operational
check
as
described
below.
Field
calibration
of the
MAC-20
may be
performed
as
follows:
1. Obtain
a current
measuring
calibration
standard
capable
of reading
TRUE-RMS
current
up to
at least
1000
Amperes
to an
accuracy
of at
least
0.257o.
This
may
consist
of a
shunt
or current
transformer,
in
conjunction
with a
digital
multimeter
or
laboratory
grade AC ammeter.
2.
Set
up the
breaker
test
set
for
normal
breaker
testing.
lf adjustments
are antici-
pated,
remove
the
MAC-20
from
the test
set and
remove
the
top cover'
3.
Connect
the
catibration
standard
to the
desired
output
tap.
lf cables
are
used,
it is
recommended
that
they
be twisted
so
as to
minimize
radiation
and
pickup
of
stray
magnetic
fields.
4. Apply
power
to test
set,
and
allow at
least
one
minute
for circuits
to stabilize.
5. Check
ammeter
zero
in all
ranges.
lf reading
on
current
meter
is
greater
than
1% of
Full
Scale,
internal
zero
adjustment
may be
required'
Copyright(C)
1 994-1998
All Rights
Reserved

Electrical Test Instruments MAC-20 Specifications

General

Brand	Electrical Test Instruments
Model	MAC-20
Category	Controller
Language	English