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De-energized, the relay spring should open the con-
tacts. Friction in the movement, relay not level, and
electrostatic attraction may contribute to difficulties
in adjusting this point. To avoid these difficulties it is
recommended to level the relay properly, at this
point omit light indicating circuit, and look for smooth
contact action. Friction in bearings or dirt in cylinder
will cause improper action.
14.8 Impedance Check
Use test connections #1 and set V
volts. The current required to close contacts of the
bottom unit should be:
Relay Range
∆ Trip Current
φ Phase-shifter set at
The Nominal M-T-Angle
φ
Phase-shifter settings are always set for 30 ° higher
than nominal maximum torque angle to account for
phase difference between phase-to-phase and
phase-to-neutral quantities. The 3φ unit maximum
torque angle is always referred to phase-to-neutral
since it receives only one single-phase current.
∆
To determine the limits for current when the MTA, θ,
is not equal to nominal maximum torque angle spec-
ified, multiply the nominal values tabulated above by
θ
sin
m
---------------
the ratio
θ
sin
θ m = original maximum torque angle
θ = recalibrated maximum torque angle.
14.9 Reverse Reach Check for KD-11
(.2 - 4.5 Ohm Range Only)
Use voltage test connection #1 and set voltages
V
=50 volts and V
1F2F
lead "23" to "terminal 15, and current lead "22" to
lead marked "21". Let phase-shifter for current to lag
V
voltage by 30
1F2F
equivalent to phase B current lagging V
°
by 60
in the reverse directions. Adjust current for
3-phase unit to operate between 10.5–12.7 am-
peres.
15. PHASE-TO-PHASE UNIT (TOP
UNIT):
Courtesy of NationalSwitchgear.com
=V
= 30
1F2F
2F3F
.2 - 4.5
.75 - 21.2 1.3 - 36.6
15.3 - 17.6 3.3 - 3.65 1.90 - 2.16
90˚
105˚
105˚
60˚
75˚
75˚
, where:
=2 volts; connect current
2F3F
°
this current connection is
voltage
BN
PHASE-TO-PHASE UNIT (T
T
COMPENSATORS) MAXIMUM
BC
SENSITIVITY ANGLE ADJUST-
MENT.
a. Use #5 test connection for T
#6 test connection for T
BC
b. Measure voltage across C
C
for T
adjustment.
2C
BC
c. Set current and voltages equal to:
Relay Range
.2 - 4.5 .75 - 21.2 1.3 - 36.6
V
= V
fault
1F-2F
∆
Trip Current (amps)
Phase-shifter set at
current lagging V
(θ
)
1F-2F
m
∆
For current limits when
angle, is not 75
˚
multiply the values above
sin
75
where β = new maximum torque an-
-------------- -
β
sin
gle for which the relay was recalibrated.
d. Vary the phase angle in both directions of the set
value, to see that a low voltage across C
No. 5) or C
(Test No. 6) capacitor (below 1 volt)
2C
is obtained at the maximum torque angle setting.
If within ±2 degrees, it can be left undisturbed. If
the minimum voltage is obtained at some other
angle, readjust phase-shifting resistor or potenti-
ometer P
or P
at the desired angle.
2A
2C
e. For core and reactor (XL
straint spring as above per Section 13.1, Initial
Spring Setting (clockwise).
f. Connect terminals 7 and 8 together and apply rat-
ed ac voltage between terminals 8-9. Adjust core
until contact arm floats in the middle of the gap.
Use a screwdriver with insulated blade to avoid
accidental contact with tap plate inserts. If contact
arm does not float in the gap then rotate the core
90 degrees and readjust.
g. Use test connection #5 Set V
V
. Note that to set this voltage you have to set
fault
voltages V
= V
first where:
A-1F
B-2F
I.L. 41-490H
AND
AB
compensator, and
AB
compensator.
for T
and across
2A
AB
30
30
30
13.9
2.97
1.72
75˚
75˚
75˚
θ
maximum torque
m
(Test
2A
) adjustments, set re-
AC
= 2 volts =
1F-2F
21
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