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Make sure that the brushes and short ing bars agree with the interna l c onnections diagram .
5.
CAUTION:
Shou l d there be a need to tighten any screws , DO NOT OVER TIG HT EN to prevent stripp ing.
6.
uRAWOUT RELAY TE STING
The IFC rel ays may be tested without removing them from the pane l by using the 12 XCA11A l four point
test probes.
The l 2 XCA 1 1 A l four point test probe makes connections to both the re l ay and the externa l
circuitry, 1vhich provides maximum f l exibil ity, but requires reasonab l e care since a CT shorting jumper is
necessary when testing the re l ay.
jumper.
See the test circuit in Figure 14.
POWER R EQUIREMENTS-GENERAL
'
' i ng current operated devices are affected by frequency .
A l l a l ternat
can be ana l yzed as a fundamental frequency p l us harmonics of the fundamenta l frequency, it fo l l ows that
a l ternating current devices (re l ays ) wi l l be affected by the app l ied waveform.
Therefore, in order to properl y test a l ternating current re l ays it is essential to use a sine wave of
current and/or vol tage.
as a finite number for any particul ar re l ay, however, any re l ay using tuned circuits, R - L or RC networks, or
saturating e l ectromagnets (such as time overcurrent re l ays ) woul d be essentia l l y affected by non-sinusoidal
Hence a resistance l imited circuit, as shown in Figures 17-1 9 , is recommended.
waveforms.
TIME OVERCURR ENT UNIT
Rotate the time dia l s l ow l y and check by means of a l am!' that the contacts just close at the zero time
dial setting .
The point at which the contacts just c l ose can be adjusted by running
or out by means of its adjusting screw .
With the contacts just c l osing at No. 0 time setting, there shoul d be sufficient gap between the
�ionary contact brush and its meta l backing strip to insure approximate l y ., 32 inch wipe.
The minimum current at which the contacts wi l l just c l ose is determined by the tap setting in the tap
bl ock at the top of the support structure.
The pickup of the time overcurrent unit for any current tap setting is adjusted by means of a spring
adjusting ring .
See Figure 1.
By t�rning the ring, the operating current of the unit may be brought into agreement with the tap setting
emp l oyed, if this adjustment has been disturbed.
diate between the various tap settings to be obtained.
that the higher tap be used.
current characteristics of Figures 6 and 7, if the re l ay has been adjusted to pick up at a va l ue other than
tap val ue, because the torque l evel of the re l ay has been changed.
Time Setting
The setting of the time dial determines the l ength of time the unit requires to c l ose the contacts
when the current reaches a predetermined va l ue .
When the time dial is set on 10, the disk must trave l the maximum amount to c l ose the contacts and therefore
this setting gives the maximum time setting.
The primary adjustment for the time of operation of the unit is made by means of the time dial .
further adjustment is obtained by moving the permanent magnet a l ong its supporting she l f; moving the magnet
toward the disk and shaft decreases the time, whi l e moving it away increases the time .
Pickup Test
Set the re lay at 0 . 5 time-dia l position and the l owest tap.
the main unit shou l d c l ose the contacts within + 3 percent of tap �a l ue current .
T ·
Test
Set the re l ay at No . 5 time -dia l setting and the l owest tap.
app l y five times tctp current to the re l ay .
Table 1 1 .
The CT circuit may a l so be tested by using an ammeter instead of the
The purity of the sine wave ( i. e . , its freedom from harmonics ) cannot be expressed
See CHARACTERISTIC section.
The spring -adjusting ring either winds or unwinds the spiral control spring .
It shoul d be noted that the re l ay wil l not necessaril y agree with the time
The re lay operating times to c l ose its contact are l isted in
GE K-45376
This adjustment a l so permits any desired setting interme
If such adjustment is required, it is recommended
The contacts are just cl osed when the time dia l is set on 0 .
Using the test connections in Figure 1 5
Using the test connection in Figure
1 0
Since non-sinusoida l waveforms
t
.
stationary contact brush in
. .
•
f
•
�
However,
14
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