GE STD15C - PICKUP TESTING; HARMONIC RESTRAINT ADJUSTMENT

GEK—45307
CAUTION
The
Relay calibration
is
accomplished
by
adjusting
resistors
Ri,
R2
and
R3.
Changes
made
in
any
one
of
these
resistors
will
affect
the
other
two
settings.
In
the
event
one setting
is
changed,
the
pickup,
harmonic
restraint,
and
through—current
restraint
adjustment
procedures
should
be
repeated
until
no
further
deviation
from
proper
calibration
is
noted.
Best
results
can
be
obtained
if
the
through-current
restraint
adjustment
is
made
only
after
the
other
two
settings
are
correct.
PICKUP
The test
circuit
for
pickup
is
shown in
Figure
14,
with
S?
open.
The
first
values
given
are
for
a
5
ampere
rated relay.
Those
in
(
)
are
for
a
1
ampere
rated
relay.
Pickup
should
be
1.5
(0.3) amperes
with
current
flowing
in
terminals
5
and
6,
and
the
tap
plugs in
the
5
(1.0)
ampere
position,
and
25%
slope
tap
setting.
The
pickup
operation
should
be
repeated
several
times,
until
two
successive
readings
agree
within
0.01 ampere
with
the
total
pickup
current
being
interrupted
between
successive
checks.
If
pickup
is
found
to
be
from
1.35
to
1.65
(0.27
to
0.33),
the
setting
should
not
be
disturbed.
With
DC
control
voltage applied
to
the
proper
terminals
of
the
relay,
the
pickup
of
the
telephone-type
relay
can
be
used
as
an
indication
of
operation
of
the
amplifier.
This
voltage
may
be
applied
as
shown in
Figure
15,
and
the
indicating
lamp
will
verify
that
the
amplifier
has
produced
an
output
signal.
Before
Ri
is
adjusted
for
pickup,
put
a
DC
voltmeter
(one
volt
scale)
on
pin
2
(-)
and
pin
8
(+)
of
the
sense
amplifier
card.
The
pins
are
counted
from
right
to
left
when
viewed
from
the
card
socket
wiring
connections.
Apply pickup
current
and
adjust
Ri
for
a
voltage
input
to
the
sense
amplifier
card
of
0.430 to
0.470
volts.
If
the
pickup
is
not
in
limits
with
this
setting,
then adjust
P1
on
the
sense
amplifier
card
to
obtain
the
proper
pickup
value.
HARMONIC
CURRENT
RESTRAINT
The
harmonic
restraint
is
adjusted
by
means
of
a
Test
Rectifier
used
in
conjunction
with
suitable
ammeters
and
load
boxes.
The
test
circuit
is
as
shown
in
Figure
15,
with
S2
closed
to
position
P.
Tests
should
be
made
on
the
5.0
(1.0) ampere
and
25%
slope
taps.
The
analysis
of
a
single-phase
half-wave
rectified
current
shows
the
presence
of
fixed
percentages
of
DC,
fundamental,
and
second
harmonic
components,
as
well
as
negligible
percentages
of
all
higher
even
harmonics.
This
closely
approximates
a
typical
transformer
inrush
current,
as
seen
at
the
relay
terminals,
inasmuch
as
its
principal
components
are
DC,
fundamental,
and
second
harmonic.
Although
the
percent
second
harmonic
is
fixed,
the
overall
percentage
may
be
varied
by
providing
a
path
for
a
controlled
amount of
by-passed
current
of
fundamental
frequency.
The
by
passed current
is
added
in
phase
with
the
fundamental
component
of
the
half-wave
rectified
current,
and
thus
provides
a
means of
varying
the
ratio
of
second
harmonic
current
to
fundamental
current.
19