Table 7-5.Troubleshooting chart for alternating-current controllersContinued
Arcing at Contacts
Pitting or Corroding of
Noisy Operation (Hum or
Vibration after Repairs
Arc not confined to proper path.
Inadequate spring pressure.
Slow in opening.
Faulty blowout coil or connection.
Excessive inductance in load circuit.
Too little surface contact.
Service too severe.
Continuous vibration when contacts are
Oxidation of contacts.
Poor fit at pole face.
Broken or defective shading coil.
Misalignment of parts.
Too much play in moving parts.
Adjust or renew arc chutes. If arcing
persists, replace with more suitable
Replace worn contacts. Adjust or replace
Remove excessive friction. Adjust spring
tension. Renew weak springs. See
Check and replace coil.
Adjust load or replace with more suitable
Clean contacts and adjust springs.
Check load conditions and replace with
more suitable controller.
Use airtight enclosure. In extreme cases,
use oil-immersed contacts.
Change or improve mounting of
temperature, or use oil-immersed
Realign and adjust pole faces.
Check coil. If correct size, shim coil until
Replace with new parts.
Realign parts and test for free movement
Tighten mounting bolts.
Replace with proper coil.
Shim parts for proper tightness, and