Electrical
Test lnstruments
MAC-20 Retrofit Package
Section lll
-
Operating lnstructions
Pick-Up
of
lnstantaneous
Element
-
1. Consult breaker
manufacturer's literature
to determine any necessary
precautions
and expected test results.
Check the breaker's instantaneous
setiing. Pickup
should
occur
at about that current.
2.
Follow
steps 1
through 18 in
general
test
procedures,
as
required,
to set
up the
breaker
test set.
3. Setup MAC-20 for
C.L. MOM.
4. Set MAC-20
RANGE
to
lowest
range that is
greater
than desired
test current.
5.
Set
TIMEBASE
to CYCLES.
6. Press PRESET
key. Adjust
preset
time to 6.0 cycles.
(This
value
may be
set
higher
or lower, depending
on how fast the breaker
trips).
7. Press PRESET
again to return
to
normal
mode.
8. Select MEMORY mode.
9. Repeatedly
jog
the INITIATE
button, while adjusting the OUTPUT
CONTROL
higher,
until the circuit breaker trips instanta neously.
This is the
approximate
pickup
point.
lf insufficient
current is obtained
at maximum
position
of the vernier,
set the
OUTPUT TAP control
to the
next
higher tap, return the
vernier to zero, and con-
tinue.
10. Close breaker under
test.
-'
11. By repeating
the test, determine
the
MINIMUM
SETTING of the OUTPUT
CONTROL, at which
the breaker under test opens immediately,
whenever the
INITIATE button is depressed.
12. Read and record ammeter
reading as instantaneous
pick-up
of
the breaker.
13.
Shut down test set, disconnect breaker,
and
prepare
for
subsequent testing or
relocation
according to steps 20 through 25 in
general procedures
outlined above.
Elecldcal
Test
lnstruments, lnc.
Page lll-5
Copyright(C) 1 994-1998 All Rights
Reserved
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