Figure 68. Bottom View Of Arc Chute; Figure 69. Primary Contacts With Circuit Breaker Open (Not Used For Contact Wear Inspection); Figure 70. Contact Inspection Area With Circuit Breaker Open - Eaton IZM40 Operation And Maintenance Instructional Manual

Operation and maintenance of
IZM low voltage air circuit breakers

Figure 68. Bottom View of Arc Chute

 Warning
arC CHUTES MUST aLWaYS BE SECUrED PrOPErLY in PLaCE BEFOrE a
CirCUiT BrEakEr iS inSTaLLED in a CirCUiT BrEakEr COMParTMEnT.
FaiLUrE TO DO THiS COULD rESULT in EQUiPMEnT DaMagE, BODiLY
inJUrY, Or EVEn DEaTH.
When the inspections are complete, position each arc chute down
over its respective set of primary contacts, and secure in place
with the screw removed earlier. Torque the arc chute screws to
35–45 in-lb (4–5 Nm).
Primary contact inspection
With the arc chutes removed, visually inspect each primary contact
structure for signs of wear and/or damage. The primary contacts
with the circuit breaker open can be viewed by looking directly down
into the arc chamber (Figure 69 and Figure 70).
Figure 69. Primary Contacts with Circuit Breaker Open
(Not Used for Contact Wear Inspection)
Alternating
V-Shaped
Plates

Figure 70. Contact Inspection Area with Circuit Breaker Open

A contact wear indicator is provided for each primary contact and
indicates whether or not the contact should be replaced. Inspection
of the contacts using the contact wear indicators is conducted only
with the circuit breaker closed (Figure 71).
WHEn Making a COnTaCT WEar inSPECTiOn, aLWaYS MakE THE
inSPECTiOn BY LOOking STraigHT DOWn inTO THE arC CHaMBEr FOr
THE PrOPEr PErSPECTiVE. ViEWing THE COnTaCT WEar arEa FrOM
an angLE COULD DiSTOrT THE ViEW.
The contact wear indicator is the relative position of the individual
contact fingers to a narrow, side-to-side ledge inside the arc
chamber. The ledge is actually part of the arc chamber. When the
circuit breaker is closed and the contacts are in good condition,
the narrow ledge is covered by the back end of the contacts
(Figure 71). If the back end of the contacts do not totally cover
the ledge, the contacts should be replaced.
arC CHUTES MUST aLWaYS BE SECUrED PrOPErLY in PLaCE BEFOrE a
CirCUiT BrEakEr iS inSTaLLED in a CirCUiT BrEakEr COMParTMEnT.
FaiLUrE TO DO THiS COULD rESULT in EQUiPMEnT DaMagE, BODiLY
inJUrY, Or EVEn DEaTH.
Once the inspection is complete, be sure the arc chutes are properly
replaced as previously described in "Functional field testing" on
page 43.
10/09 AWB1230-1605
Arcing Contact (Toe)
Integral Arc Runner
Stationary Main Contact
Moving Main Contact
Side View
 nOTiCE
 Warning
MOELLER www.moeller.net/de/support
Effective October 2009
45