Western Electric 407A-4, Instruction Manual

Page: 104 / 136

MAINTENANCE OF MOTOR-OPERATED PLATE CI RCUIT BREAKER
Circu it breakers, as distinguished from other type s of
cir cuit-interrupting devices such as contactors and relays,
are primarily designe d for infrequent interruptions of ex­
tremely he avy overloads . The maintenance required on a cir­
cuit breaker will depend upon the number of overload opera­
tions the breaker has performe d. It is recommended that the
following maintenance schedule be followed for the plate c ir­
cuit breake r :
At shut-down each night the cas e of the breaker shoul d
be felt to determine whether it is at any materially higher
temperature than normally exists after regular operation.
Monthly or After 20 Overload
Whichever Occurs First
The cover of the breaker should be removed and the con­
tacts and arc-spl itt ers ins pected. If it appears necessary,
the s tati onary contacts or the arc-splitters may be re­
placed. If the moving contacts or other parts of the
breaker nee d replacing or servicing; the work shoul d be re­
ferre d to the s ervi c e department of the Westinghous e Elec­
tri c and Manufacturing Company, H.a;yne s Ave. and Lincoln
Highway, Newark, N. J. , attention
Mr.
L. M. Brown.
In addition to the visual inspecti on, a dielectric test
should be made on the breake r . T o d o this the breaker
should be iso lated from the other power circu its in the dis ­
tribution cabinet by opening switches D55P and D56P. With
the breaker closed, 2200 volts should be applied b etween
each pole and ground, and with the breaker open the voltage
should be applie d between the l ine and load terminals of
each pol e . The test voltage can be obtained from a poten­
tial trans former equipped with pr imary fus es . The breaker
97