Cleaning Relay Contacts; Figure 4-1. Armature Stop Pin Location - Hitachi PN-150BE Manual

SEE ENLARGED AREA
b. Insert the impregnated strip between the armature stop pin and its point of
contact on the relay pole face. While applying moderate pressure to keep the
armature closed, pull the strip back and forth in a circular motion and continue
for several seconds to ensure a sufficient amount of graphite transfer.
c. It is not necessary to observe a significant deposit of graphite since most of
what is required can only be determined by means of a microscope.
3. Recheck relay calibration and prepare relay for return to service.

4.2.2. Cleaning Relay Contacts

This section covers recommended methods for the preparation and cleaning of relay
contacts.
After contacts have been filed and/or after adjustments have been made to meet
calibration requirements, the contacts should be cleaned in accordance with the
procedure given in Sections 4.2.2.1 and 4.2.2.2.
If it is desired to use an aerosol spray for cleaning relay
contacts, only virgin Freon TF (available from Miller
Stephenson Chemical Co. As MS-180 or MS-230 Contact
Re-Nu Freon TF) is approved by STS USA for cleaning
contacts with the driver attached to the contact springs.
4.2.2.1. General
a. Preliminary information
The Dacron covered washing and drying strips should be used to clean no more
than 12 front (carbon) and 12 back (silver) contacts after which they should be
washed (while still on the metal strip) before re-use. The Dacron cloth covered
metal strips should be cleaned using a mild soap or detergent and water, rinsing
thoroughly and allowing to dry.
Copyright 2019
PN-150BE Biased High Efficiency Vital Relay

Figure 4-1. Armature Stop Pin Location

CAUTION
SM 4551L, Rev. 0 1, March 2019
SAFETY PINS
STOP PIN
4-4