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6.4 Undervoltage Unit
The voltage unit is calibrated to close its contact
when the applied voltage is reduced to 80 volts.
The voltage unit can be set to close its contacts
from 70 volts to 90 volts by adjusting the resistor
located next to the directional unit (to the left of the
upper operating unit). The spiral spring is not dis-
turbed when making any setting other than the cal-
ibrated setting of 80 volts.
The undervoltage unit range of 70 to 90 volts is
equivalent to 80 to 104 V
mal system voltage). This is because the voltage
on the unit is equal to 1.5 times V
6.5 Directional Setting
There is no setting to be made on the directional
unit.
6.6 Indicating Contactor Switch (ICS)
No setting is required on the ICS.
7. INSTALLATION
The relays should be mounted on switchboard
panels or their equivalent in a location free from
dirt, moisture, excessive vibration, and heat.
Mount the relay vertically by means of the four
mounting holes on the flange for semi-flush mount-
ing or by means of the rear mounting stud or studs
for projection mounting. Either a mounting stud or
the mounting screws may be utilized for grounding
the relay. The electrical connections may be made
directly to the terminals by means of screws for
steel panel mounting of the terminal studs fur-
nished with the relay for thick panel mounting. The
terminal studs may be easily removed or inserted
by locking two nuts on the stud and then turning
the proper nut with a wrench.
For detailed FT Case information refer to I.L.
41-076.
8. ADJUSTMENTS AND MAINTENANCE
The proper adjustments to insure correct operation
of this relay have been made at the factory. Upon
receipt of the relay, no customer adjustments,
other than those covered under "SETTINGS,"
should be required.
8.1 Performance Check
The following check is recommended to insure that
the relay is in proper working order: Relay should
be energized for at least one hour.
A. Distance Unit (Z)
(or 67% to 87% nor-
L-L
.
L-N
1. Connect the relay as shown in Figure 14 with
the switch in position 2 and the trip circuit
deenergized.
2. Make the following tap settings:
T
= 11.5
A
S
= 2
A
M
= -.03
A
T
link in middle block should be set for +T
C
direction.
This setting corresponds to Z
Adjust the phase shifter for 90° current lagging
the voltage.
3. With the terminal voltage at 80 volts,
increase current until contacts just close.
This current should be within ±3% of 2.25
amps (2.32 - 2.18 amps). This value corre-
sponds to 1.5 Z
applied to terminals 4 and 5 is equivalent to
1.5 V
voltage, or
IN
V
80
1N
Z
=
--------- -
=
------ -
A
I
1.5
1
4. Adjust phase shifter for 90° current leading
the voltage.
5. With the terminal voltage at 80 volts increase
current until contacts just close. This current
should be within ±3% of 19.0 amps. (19.6 -
18.4 amps.) This value corresponds 1.5Z
setting for the same reason as explained
above.
5. Contact Gap
The gap between the stationary contact and
moving contact with the relay in deenergized
position should be approximately.040".
B. Directional Unit Circuit (D)
1. Connect the relay as shown in Figure 14 with
the switch in position 1 and the trip circuit
deenergized.
2. With a terminal voltage of 1 volt and 5
amperes applied, turn the phase shifter to
13° (current leads voltage). The contacts
should be closed. This is the maximum
torque position.
3. Raise the voltage to 120 volts and vary the
phase shifter to obtain the two angles where
41-748.21C
T
= 2.55
C
S
= 1
C
M
= -.09
C
= 23.7, Z
= 2.80
A
C
setting since the voltage as
A
1
×
--------- -
=
23.7Ω
2.25
C
C
13
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