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3.5. Contact Cleaning Procedure
3.5.1. Contacts that are Severely Burned
1. Using a 600-grit emery paper strip, folded with grit side out so that both contacts
can be burnished simultaneously, stroke the contacts in the direction of the
contact wipe.
2. Using the burnishing tool, stroke the contacts several times in the direction of the
contact wipe.
3. Place the paper strip between the open contacts, then close the contacts and
withdraw the paper strip.
4. Repeat Step 3 several times, if necessary.
5. Using the alcohol spray, give the contacts a degreasing/wash.
6. Place the paper strip between the open contacts, then close the contacts and
withdraw the paper strip.
7. Repeat Step 6 several times, if necessary.
3.5.2. Contacts with Heavy Tarnish, Slightly Rough or Pitted Surface
1. Perform the procedure in Section 3.5.1, Steps 2 through 7.
3.5.3. Contacts with Surface Film or Oxidation (not Pitted)
1. Perform the procedure in Section 3.5.1, Steps 6 and 7.
3.6. Check-Out Procedure (Performance Test)
1. Conduct the contact adjustment procedure in Section 3.7.5.
2. Conduct the electrical calibration procedure in 3.
The above steps must be done before returning the relay to service.
3.7. Repairs, Replacement and Adjustment of Relay Components
Since the contacts are the major wearing parts in this relay, in most cases the relay can
be restored to proper operation by dressing and readjusting them.
Copyright 2019
SM 4574F, Rev. 4, March 2019
PV-250 Track Relay
3-9
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