Western Electric 407A-4, Инструкция по эксплуатации

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does not support life ; if it should wholly fill a room, a
person in that room would suffocate from lack of oxygen.
For this r eason the bleeder and bl owoff valves are vented to
the exterior and proper precautions should be taken in dis ­
charging cylinders or performing any other oper ations in­
vo lving the freeing of the gas .
DESCRIPT ION AND SERVICING OF TYPE Dn CONTACTORS
IDCATED IN POWER DISTRIBUTI ON CAB INET
Magnet
The magnet is of the solenoid type, a form leas t likely
to produce acc ide�tal c lo s ing due to t ilting or shock. The
armature is of flexibly stacke d laminations, minimiz ing the
chance of objectionable magnetic noise or hum. The station­
ary magnet may be removed for replacement of the coil by
first removing the armature stop bracket, held to the front
of the magnet by two screws , and then removing the two
s crews securing it to the back plate .
Operating Coil
The coil is designe d for continuous duty at 100 per
cent of its rating . It will oper ate the contactor s atis­
factorily at from 85 to 110 per cent of its rated voltage .
To remove the co il, first dis connect the co il leads
and remove the magnet stator from its place on the back
plate. Then loosen the coil retaining s crew and sl ide out
the two channe l-shaped armature guides, allowing the coil
to drop free from the magnet frame .
Contacts
The self-aligning double-break moving contacts are
carried on a cros sbar of insulating material secured to the
armature of the magnet . There are no shunts or sl iding con­
tacts to wear or produce other troub le . The contact tips
are of s ilver, requir ing almost no attention. Only in cases
9 5