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GEK-26423
TABLE III
OHMIC REACH
MINIMUM
MAXIMUM
TAP SETTING
AMPERES
AMPERES
0.5
32
60
1.0
16
60
1.5
12
60
2.0
8
60
3.0
6
60
Set the phase shifter so that the current leads the voltage by 210 degrees.
The contacts of each
unit should remain open from zero to 60 amperes.
3.
Maximum Torque Angle
-
The maximum torque angle of the mho-type units can be checked using the
connections shown in Figure 10, but with the E tap disconnected.
The operating current should be set
for 5 amperes, with polarizing voltage at 120 volts.
With the phase shifter set so that operating current leads polarizing voltage by
3Q0,
the left contact
of the unit will be closed.
Next find the angles on either side of the
3Q0
position which cause the left
contact to just open.
These are the zero torque angles of the unit.
The maximum torque position will be
at the bisector of the angle between the two zero torque lines.
For example, assume that for a particular
unit the left contact just opens at 110° and 3100.
The angle of maximum torque will be:
(110
+
310)
=
210°, ie 300 lead
The maximum torque angle of the units should be at 30° lead, ±3°.
This is the angle by which the
operating current leads the polarizing voltage for a particular unit.
4.
Pickup Check
-
The following check is to determine that the ohmic reach of each unit is witifl
+14 percent of the minimum reach as given on the nameplate.
These checks should be made with the E
taps
set at 100 percent and the voltage adjusted for the value shown in Table IV for the specific ohmic range
and with the relay connected as shown in Figure 10.
Set the phase shifter so that current leads
voltage by 30 degrees, check that the current required to close the contacts falls within the range shown
in Table IV.
Resistor R
1 1
-R
12
-R
13 should not be used to adjust pickup.
The resistors are used to make
the phase angle of the restraint circuit the same as the phase angle of the polarizing circuit.
TABLE IV
REACH
RESTRAINT
POLAR.
PHASE
UNIT
LINK
APPLIED
APPLIED
PICKUP
ANGLE
0-N
SETTING
VOLTAGE
VOLTAGE
CURRENT
°LEAD
0.5
0.5
20V
1?OV
34.4
-
45.6
30°
1.0
1.0
25
120
21.6
-
28.5
300
1.5
1.5
35
120
20.0
—
26.6
300
2.0
2.0
35
120
15.0
-
20.0
300
3.0
3.0
70
120
20.0
-
26.6
300
5.
Compensating Winding Check
-
The following check is to confirm that the relative polarity of the
compensating windings between terminals 9-10, is correct.
Use the basic test connections of Figure 10,
but connect the current circuits as tabulated in the following:
—
UNIT
Ii TO
12 TO
JUMPER
STUD
STUD
STUDS
Ml
3
10
4-9
M2
5
10
6-9
M3
7
10
—
8-9
With voltage, E 2 tap, and phase angle set as in the pickup check (4), measure the current required to
close the left contact of each unit.
The current should be one half the values listed in Table 1V.
11
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