GE IRT51 E, Инструкция по эксплуатации, Страница: 18 / 51

GEK-86038
2. The wipe on each no rmally-o pen contact should be a pproximately 0.005 inch .
This ga p can be checked by inse rting a 0. 005 inch feeler g age between the
armature and the pole piece and o pe rating the a rmatu re by h and. The normally-
o pen contacts should make with the 0. 005 inch feeler gage in place.
3 .
The contact pressu re should n ot be less than ten grams , measu red at the contact
tips.
4 . Check for roughness o r binding on the interlocking a rms on the latching
telephone relay unit on the IRT51G and IRT51H models. Use a fine fi 1 e to d ress
the interlocking a rms only if binding o r roughness is observed.
CONTACT INSPE CTION AND CLEANING
1.
All contacts should meet in alignment.
2 . Check for contact condition. If ta rnishing o r mil d pitting is observed , the
contacts sho uld be reconditioned with a flexible burnishing tool . A bu rnishing
tool is a flexible strip of metal with an etched-roughened su rface , resembling
a su perfine file. The polishing action is delicate so that no sc ratches a re
left , yet co rrosion and mild pitting a re cleaned tho roughly and quickly. Its
flexibility assu res the cleaning of the actu al points of contact . D o not use a
knife edge , file , abrasive pa per o r cloth to clean relay contacts.
AUXILIARY BRUSHES
CAUTION
Every circuit in the IRT51 drawout case has an auxiliary brush. I t is
especially important on current circuits and other circuits with shorting
bars that the auxiliary brush be bent high enough to engage the connecting
plug or test plug before the main brushes do. This will prevent the
current transformer secondary circuits from being opened or the current
circuits from being interrupted.
RHEOSTAT CLEANING
Al though the sliding contact in the tem perature selection rheostat is resistant
to ta rnishing , it is not i11111une to ta rnishing and sho uld be cleaned as pa rt of the
n o rmal relay maintenance program. Tu rning the tempe ratu re dial back and fo rth
several times will mechanically clean the slider tip contact within the rheostat and
will usually be adequate. If a mo re tho rough cleaning is required , a good quality
liquid contact cleaner can be used.
ELECTRICAL TESTS
All alte rnating cu rrent o pe rating devices a re affected by frequency. Since
non-sinusoidal waveforms can be analyzed as a fundamental frequency plus ha rmonics
of the fund amental frequency , it follows that alte rnating current devices, such as
the IRT type relays , will be affected by the a pplied -waveform. The pu rity of the
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sine wave , that is its freedom from harmonics , cannot be expressed as a finite
number for any pa rticula r relay . Therefo re to test alternating cu rrent relays , it
is essential to use a sine wave of cu rrent o r voltage of the co rrect frequency and
good wave fo rm.
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