Electrical Test Instruments MAC-20 User Manual

Electrical
Test
lnstruments
MAC-20
Retrofit
package
Section lll
-
Operating lnstructions
RATIOING
CURRENT
TRANSFORMERS
To
conduct
a ratio
test on
a current
transformer,
a
good
multi-range
bench
ammeter
is
required
in
addition
to the breaker
test
set. The
breaker test
set
supplies
primary
current
to the
transformer
and
the bench
ammeter
is
used to read
the
transformer
secondary
current. lt
is suggested
that
a
graph
of the
test results
be
plotted.
primary
current
should be
the abscissa
and corresponding
secondary
current
the
ordinaie
of the
graph.
wARNING:
lt is extremely
important
that
the secondary
circuit
of the
current trans-
former
never
be broken
or
opened
while the
primary
circuit is
energized.
should
the
secondary
circuit
of an
energized
current
transformer
be opened,
the
collapsing
magnetic
field
generates
an
extremely
high voltage
across
the
open ends
of the
circujt
until the resultant
arc is
extinguished.
Under
these
conditions,
personal
injury
and/or
damage
to
the current
transformer
under
test
are
probable.
1. Follow
steps 1
through
18 in
general
test
procedures,
as required,
to set up
the
breaker
test
set.
connect
the current
transformer
primary
terminals
to the
breaker
test set
common
terminal
and
the
proper
output
tap terminai.
Connect
the current
transformer
secondary
terminals
to
the bench
ammeter.
Set the MAC-20
to N.O. mode.
Set LATCH
on.
Press
and release
INITIATE
button;
CLOSE or OUTPUT
ON tight
shoutd
glow,
timer
should
operate, and
current
should indicate
on display.
Adjust
OUTPUT
CONTROL
higher until
the desired
current
transformer
primary
current
is read
on the MAC-20
ammeter.
Adjust
OUTPUT
TAp switch,
if necessary,
to
obtain required
current.
Read
and record
the readings
on both
the breaker
test set
(MAC-20)
and
the bench
ammeter.
Repeat
steps
6 and 7 until
the desired number
of test
points
have
been obtained.
Note:
lt is suggested
that test
points
be
obtained in
multiples
of the
current trans-
former
rating. For
instance,
lor a20015
current
transformer,
test
points
would
be
obtained
at
primary
currents
of 200, 400,
600, 800 amperes,
etc.
Shut down
test set, disconnect
CT,
and
prepare
for
subsequent
testing
or relocation
according
to steps 20 through
25 in
general procedures
outlined
above.
2.
.,
4.
5.
6.
7.
8.
9
Electrical Test
lnstruments,
lnc.
Page lll-'16
Copyrisht(C) 1
994-1998
All Righls Reserved

Electrical Test Instruments MAC-20 Specifications

General

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