Pole Unit; Primary Moving Contacts - Eaton CM52 Instruction Booklet

Instructions for the Eaton Type CM52
Network Protectors 800 to 4500 Amperes
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construction provides high strength structural
properties, excellent dielectric ch aracteristics and
resistance to arc tracking.
construction app roach provides suppo rt while
isolating and insulating power conductors.
1. A 2-Piece
composite resin case enclosed current
path and arc chamb ers. The chambers
act to chann el arc gas es up and out o f
the circuit breaker during interruption.
2. The operating mechanism sits on the
front of the case and is electrically
isolated from cu rrent contact structures.
An insulating dead front cov er cov ers
the completed break er.

4.3 POLE UNIT

A current carrying pole unit is individually
enclosed and rigidly supported by the cas e. The
individual chambers provide fo r pole unit
isolation and insulation from on e another. Each
pole unit has one p rimary contact assembly,
which consists of a moving portion.
4.3.1

Primary Moving Contacts

Depending upon the fram e size, each p rimary
moving contact assembly is comprised o f
multiple individual copper contact
Fig.11a Main Contacts Open
Effective 11/05/08 (super cedes 11/19/03) IB 52-01-TE
The 3-piece
engineered thermoset
fingers
Instruction Booklet IB 52-01-TE
connect ed to the load conductor through flexible
braided connectors. Two fl exible connectors are
used to connect each finger to the load
conductor. The number of fingers used depends
upon the circuit breaker's continuous and short-
circuit current ratings.
The middle four contact fingers perform both the
main and arcing contact functions of the moving
contacts. A highly conductive alloy pad is part
of the cont act finger and functions as the moving
main contact, and is called the " Heel".
A contact wear indictor is provided for each
contact assembly. When making a contact wear
inspection, always look straight down into the
arc chamber to eliminate parallax. The contact
wear indicator is a side-to-side ledge, whi ch is a
part of the arc chamber.
closed and in good condition, the ledge is
covered by the back edge of the moving contacts.
If the back edge of the moving contacts does not
totally cover this l edge, the contacts should be
replaced
Fig. 11b Main Contacts Closed
EATON COrPOrATION www.eaton.com
Effective October 2010
IB -52-01-TE
With the contacts
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