QRA\i_OUT
RELAY
.JESTIN§__
The
I
FC
relays
may
be
tested
with out
removing
them
from
the
pane
1
by
using the l
2XCA11A1
four
point
test
probes.
The
12XCA11Al
four point
test
probe
makes
connections to both the relay
and
the
external
circuitry,
which
provides
maximum
flexibility,
but requires reasonable care since a
CT
shorting jumper
is
necessary
when
testing
the relay.
The
CT
circuit
may
also
be
tested
by
usfog
an
ammeter
instead of the jumper.
See
the
test
circuit
in Figure
15.
fOIJ[R
REC)IJIREMENTS
G_ENERAL
All
alternating
current operated devices are affected
by
frequency, Since non-sinusoidal
()
waveforms
can
be
analyzed
as
a
fundamenta·1
frequency plus harmonics of the fundamental frequency,
it
('"".".·
follows
that
alternating
current devices (relays) will
be
affected
by
the applied
waveform.
!'•
.
_,,..
Therefore, in order
,to
properly
test
alternating
current relays
it
is
essential
to
use
a
sine
wave
of
current
and/or vo'ltage.
The
purity of the
sine
wave
(i.e.,
its
freedom
from
harmonics)
cannot
be
expressed
as
a
finite
number
for
any
particular
relay,
however,
any
relay using tuned
ci
rcu'its,
R-L
or
RC
networks, or
saturating
e 1 ectromagnets (such
as
time overcurrent re 1 ays)
wou·1
d
be
essentially
affected
by
non-sinusoidal
waveforms.
Hence
a resistance limited
circuit,
as
shown
in
Fiqures 16-18,
is
recommended.
llJ:1E
OVER~YRRENl_YNIT
Rotate the time dial slowly
and
check
by
means
of a
lamp
that
the contacts
just
c·lose
at
the zero
time dial
setting
.
.
The
point
at
wnicn
the contacts
just
close
can
be
adjusted
by
running the
stationary
contact brush
in or out
by
means
of
its
adjusting screw.
~iith
the contacts
just
closing
at
No.
O time
setting,
there should
be
sufficient
gap
between the
stationary
contact brush
and
its
metal backing
strip
to insure approximately 1/32" wipe.
The
minimum
current
at
which
the contacts
will
just
close
is
determ·ined
by
the tap
setting
in the
tap block
at
the top
of
the support
structure.
See
Characteristic
section.
The
pickup of the time overcurrent un'it for
any
current
tap
setting
is
adjusted
by
means
of a
spring-adjusting
ring.
See
Figure 1.
The
spring-adjusting ring
either
winds
or
unwinds
the
spiral
control spring.
By
turning the
ring,
the operating current of the unit
may
be
brought into agreement
with the tap
setting
employed,
if
this
adjustment
has
been
disturbed. This adjustment also permits
any
desired
setting
intermediate between the various tap
settings
to
be
obtained.
If
such adjustment
is
re
qui
red,
it
is
recommended
that
the higher tap
be
used.
It
should
be
noted
that
the re 1
ay
11il
1 not
necessar·ily agree with the time current
characteristics
of .Figures 6-8
and
20-22,
if
the relay
has
been
adjusted to
p·i
ckup
at
a
va
1
ue
other than tap
va
1 ue, because the torque
1eve1
of the re 1
av
has
been
changed.
~11
Time
Setting \
·\·1
The
setting
of the time dial determines the length of time the unit requires to close the contacts U
when
the current reaches a predetermined value.
The
contacts are
just
closed
when
the time dial
is
set
on
O.
When
the time dial
is
set
on
10, the disk
must
travel the
maximum
amount
to close the contacts
and
therefore
this
sett'ing gives the
maximum
time
setting.
The
primary adjustment
for
the time
of
operation of the unH
is
made
by
means
of
the time
dial.
However,
further
adjustment
is
obta·i
ned
by
moving
the permanent
magnet
a 1
ong
its
supporting she 1
f;
moving
the
magnet
toward
the disk
and
shaft
decreases the time, while
moving
it
away
increases the time.
Pi
ck
up_
Test_
Set the relay
at
0.5 time dial position
and
the lm;est tap.
Using
the
test
connections in Figure 16(:'1
the
ma·in
unit should close the contacts within
±3%
of
tap value current for
60
Hz
relays
and
within lliii
±7.5%
of tap value
current
for
50
Hz
relays.
10
Courtesy of NationalSwitchgear.com
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