45
10/09 AWB1230-1605
Effective October 2009
Operation and maintenance of
IZM low voltage air circuit breakers
MOELLER
www.moeller.net/de/support
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 (
and
).
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 (
nOTiCE
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
). If the back end of the contacts do not totally cover
the ledge, the contacts should be replaced.
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.
Once the inspection is complete, be sure the arc chutes are properly
replaced as previously described in “Functional field testing” on
Arcing Contact (Toe)
Integral Arc Runner
Stationary Main Contact
Moving Main Contact
Side View
