GEK-49848A
T I ME OVERCURRENT UN I T
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1 . S et the ta p screw on the de s i red ta p . U s i n g the tes t ci rcui t i n F i g . 23,
a p pl y a pprox i ma tel y twi ce ta p val ue current unt i l the contacts just cl ose .
Reduce the curren t unti
1
the
1
i ght i n s er i es wi th the co ntacts begi ns to
fl i cker . Th i s val ue o f current s houl d be wi thi n fi ve percent of ta p val ue .
2 . Check the o pera t i n g t i me at s ome mul ti pl e of ta p val ue . Thi s mul ti pl e o f
ta p val ue may be fi ve ti mes ta p rati n g or t h e maxi mum faul t current for
wh i ch the rel ay mus t coord i nate . The val ue used i s l eft to the di screti on
of the user .
D I RECTI ONAL UN I T
Check d i rect i onal un i t pol a r i ty; see ACCEPTANCE TESTS .
INSTANTANEOUS OVERCURRENT UN I T
(
D I RECTI ONALLY
C heck pi ckup s etti n g; see ACCEPTANCE TESTS .
INSTANTANEOUS UN I T
(
NON- D I RECT I ONALLY
1 . Sel ect the des i red ran ge by maki n g the pro per conn ect i ons at the rear of
the rel ay ( see i ntern al connecti ons d i a gram
)
.
Whenever pos s i bl e, al ways
s el ect the h i gher ran ge s i nce i t ha s a h i gher conti nuous rat i n g .
2 . Set the i ns tantaneous un i t to pi ck u p a t the des i red current l evel .
See
the ACCEPTANCE TESTS secti on .
PERIOD I C CHECKS AND ROUT INE MAINTENANCE
In v i ew of the vi tal rol e of protecti ve rel ays i n the o pera t i o n of a power
sys tem i t i s i mportant that a per i od i c tes t pro gram be fol l owed .
It is reco gni zed
that the i nterval between per i o d i c c hecks wi l l vary depen d i n g upon en v i ronment, type
o f rel ay and the user•s experi ence wi th per i od i c tes ti n g .
Unt i l the user ha s
accumul a ted enough experi ence to sel ect the tes t i nterval bes t sui ted to hi s
i nd i v i dual requi rements, i t i s sugges ted that the po i nts l i s ted bel ow be checked a t
an i nterval o f from one t o two yea rs .
These tests are i ntended to make sure that the rel ays have not dev i ated from
the i r ori ginal settings . If devia t i o ns are encountered, the rel ay must be retested
and servi ced a s descri bed i n th i s manual .
TARGET AND S EAL- IN UN I TS
1 . C heck that the un i t pi cks up at the va l ues s hown i n Ta bl e 1 1 .
2 . C heck that the un i t dro ps out at 25 percent or more o f ta p val ue .
T I ME OVERCURRENT UN I T
1 . Perform pi ckup test as des c r i bed i n the INSTALLATI ON sect i on for the t a p i n
s erv i ce .
2 . Perform the t i me tests as des c r i bed i n the INSTALLATION sect i on .
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