User Manual

4-18 Maintenance
1502-UM051E-EN-P – June 2013
Altitude Adjustment Vacuumcontactorsaresensitivetothealtitudeattheinstallationsite.isisdue
to the fact that the atmospheric pressure assists in closing the main contacts by
exertingforceonthebellowsatthemovableendofthevacuumbottles.Since
thisforceisproportionaltothedierencebetweeninternalbottlepressureand
externalatmosphericpressure,thereturnspringmustbeadjustedfortheap-
propriatealtitudes.Contactorsarefactorysetforthealtitudeatwhichtheyare
originallyinstalled.Ifacontactorisrelocatedtoadierentaltituderange(see
Table4.A),aspringadjustmentisnecessaryforproperoperation.
 efollowingprocedureshallbeusedtomakethecorrectsettings.
 1. Determinewhataltituderangethecontactorissetupforbycheckingthe
ratinglabel(alsorefertotheCatalogNumberExplanation).
 2. Measureandrecorddimension“A”asshownperFigure4.24.
Note:Dimension“A”willvaryfromcontactortocontactor,thereisno
predetermined value.
Compression Bolt
Locking Nut
Return Spring
AA
Figure 4.24 – Return Spring Assembly
 3. Loosenthecompressionboltlockingnutandadjustthepositionofthe
compressionboltaccordingtoTable4.A.Dimension“A”ischangedbythe
amountshownonthetable.Forexample,ifthecontactor’sexistingrange
is0-1000mandthedesiredrangeis3000-4000m,increasedimension“A”
by4.93mm(0.194in.).Ifthecontactor’sexistingrangeis4000-5000m
andthedesiredrangeis2000-3000m,decreasedimension“A”by2.69mm
(0.106in.).Aerdimension“A”hasbeensetforthedesiredaltituderange,
re-tightenthelockingnut.