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A . Use connection for Test No. 4 and adjust
the voltage between PH. 1 and 1 F and between PH. 2
and 2F for 40 volts each so that the resultant volt
age V 1 F2F equals 40 volts ( 1 20-40 V-40 = 4 0 V).
B . The current required to make the cylinder
unit contacts open should be between 2 . 8 8 and 2. 98
amperes at an angie of 75 " current lag.
C. Repeat B while using connections for Test
No. 5 and Test No. 6. The difference in values of
current that make the contacts close for each of the
three test connections should not be greater than
4% of the smallest value.
If the electrical response is outside the limits a
more complete series of test outlined in the section
"Calibration" may be performed to determine which
component is faulty or out of calibration.
Check the time-delay unit by applying rated D. C.
voltage across terminals 18 and 20 . Opening the
cylinder unit contacts should cause the telephone
type relay to pick up. It should drop out when the
cylinder unit contacts close.
ROUTINE
MAINTENANCE
A ll relays should be inspected periodically, at
such time intervals as may be dictated by experi
ence, to insure that the relays have retained their
calibration and are in proper operating condition.
A ll contacts should be cleaned periodically. A
contact burnisher #182 A 8 36HO 1 is recommended for
this
purpose.
The
use
cleaning contacts is not recommended, because of
the danger of embedding small particles in the face
of the soft silver and thus impairing the contact.
Electrical Checkpoints
A .
Cylinder Unit
Using the connections for Tests Nos. 8 and
9
Figure
set the phase shifter so that the current
eo .
lags voltage by
The current required to open
the contacts should be within the limits specified
for each voltage. Note that for the forward reach,
connection 8 , the impedance measured by the relay
V L -
L. R everse reach, connection
z
L =
2I L
sured by the relay in this test is
10
of abrasi ve m aterial for
9
of
9,
mea-
V L
- L
�
R =
- 1/ 3 Z L . H ere V L - L is phase -to
3 I L
phase voltage and I L is phase current.
VOLTS
T EST
V l F2F
NO.
&
V 2F3F
40
8
80
40
9
8 0
tt
P hase A ngle M eter Set for
t
To determine the limits of current when
o,
equal to 75
m ultiply the nominal values tabu
lated above by the ratio sin 75
Note that Tests Nos. 8 and
of checking the forward and reverse balance points.
These tests require a polyphase voltage supply and
only a single- phase current.
R eferring to vector diagrams of Figure 10, one
can see how the forward and reverse balance points
are determined with a balanced three-phase current.
Comparing this to the artificial single-phase current
method in Figure 11 it is obvious that a similarity
exists between the two. This similarity makes it
possible
to accurately
points using a single-phase current at the relay
m aximum torque angle only.
The circle characteristics of Figure 5 cannot be
checked using a single phase current. A polyphase
current is required, with test connections as per
7
9,
Test No.
Figure
to plot the characteristic cir
cle. The reach of the relay for this connection i s
V L
- L Ohms.
v=
�
3 I L
REPAIR CALl BRATI ON
Use the following procedure for calibrating the
relay if the relay has been taken apart for repairs or
the adjustments disturbed.
(8 = 75°)
t
&
AMP E R ES
I
I
min
max
2.80
3 . 0
5.75
6. 90
75tt
5.9 tt
5.
12. 0
11. 4
8
o
+ 30
8
is not
o
sin
9
are artificial methods
check the
relay balance
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