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Negative Sequence Filter
Adjustment. of the filter
resistor to obtain
no response to positive sequence
currents
is
obtained as follows:
a
)
Connect terminal
8
to terminal
14
b
)
Remove tap screw from the
COQ
element
c
)
Pass
10
amperes
into
terminal
7
and out
terminal
13
d
)
With a low reading, high resistance Rectox
voltmeter,
measure
the
voltage
between
*
termiual
8
and the tap plate.
e
)
Place the voltmeter across terminals
7
and
8.
Adjust the
resistor lead on the right
of the reactor
until
the voltmeter reads
1.732
times the voltage reading of step
(
d.
Adjustment of the filter resistance to ob
tain no response to
the zero sequence current
is conveniently made by
referring to Fig. 5.
Pass 5 amperes into terminal 8 and 10 amperes
into terminal 7.
Adjust the resistor lead on
the left of the reactor until the voltmeter
reads zero.
TIME CURVE CALIBRATION
With the time dial set on " 0"·,
wind up the
spring until approximately
5-1/2 convolutions
show.
This is an initial rough adjustment.
From this preliminary setting,
minimum tap setting and time dial
"11",
adjust the permanent magnet
relay operates in
8 . 2 seconds
and
using
setting of
until the
with 15.6
amperes single phase or 3
per
unit between
terminals 8 and 14.
This adjustment is made
by means of the damping magnet screw.
A dia
gram of the test connections is shown
in
Fig.
6.
Next adjust the spring tension until the
relay will close contacts in 90 seconds with
5.2
a
m
p
e
r
e
s single
per unit negative
between terminals 8
phase (tap value or one
sequence current)
applied
and 14.
This adjustment
is made by
means of
the spiral spring ad
juster. All spring convolutions must be free.
TRIP CIRCUIT
Universal Trip
This combination uses a 2.0 amp.
contactor
s*itch and a 0.2 amp.
connected in parallel.
operation
indicator
Adjust the conta.ctor
switch and indicator a.s outlined below;
Contactor Switch - Turn the relay up side
down.
Screw up the core screw until the con-
tact ring starts rotating.
Now back off the
core until the contact
ring stops rotating.
Back off the core screw one more turn and lock
in place.
Adjust the two nuts a.t the bottom
of the switch so that
there is
3/32 inch
clearance between the moving contact ring and
the stationary contacts in the open position.
The guide rod may be used as a. scale as it has
52 threads per inch, therefore,
5
turns of the
nuts will equal approximately 3/32 inch.
Combination Test - Close the main relay con
tacts and pass 2.25 amps d.c. through the trip
circuit.
The conta.ctor switch must pick-up.
Adjust the operation
indicator by moving the
flag holder such that the indicator operates
with the application of
the 2.
25
amps. Pass
30 amps d. c.
through the trip circuit.
The
indicator and contactor switch must not stick
in the operated position when the current is
interrupted.
7
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