OP-755 Part 2 Pages 197-401 - Personal Page of GENE SLOVER

272
39. Control l er . - The controller is an across-the-line,
magnetic motor starter of shockproof design, semiautomatic
operation, waterproof enclosure, arranged with an externally
operated door interlock disconnect switch. It is an assembly
of commercially manufactured parts (ward Leonard Elec. Co.),
providing control and protection for the above described motor.
The cabinet units for each hoist are mounted in the machinery
space of the upper projectile flat. Their starting circuit
push-button stations are located at the upper end of the hoist
at the hoist operator's station. Each circuit includes a "St.op"
push button at the lower end door operator's station. These
arrangements and othe~ details of the controller are shown on
the diagram and data of drawing number 231703. The protective
features there indicated comprise undervoltage, short circuit
and overload devices of the following types.
(a) Short circuit protection. -Adjustable automatic
trip circui t breaker which operates to open
the motor supply at settings between 1100 to
1200 amperes.
(b) Uruier u o l t age protection. - A contactor dropout
arrangement which functions at potentials
of 110 volts or less;. sealing voltage approximately
360.
(C) Overload protect ion. - The motor overload protection
is of the inverse time limit thermal
type with magnetic reset mechanism actuated
by closing the starting circuit. Starting
overload is prevented by arrangement of the
starting circuit to include an interlock switch
(#13 on pls. 7-14) in the A-end. This is only
closed when the pump yoke is at neutral.
40. The controller is arranged with a "power=on" circuit
connected to a solenoid of the A-end control. This circuit is
closed when the main line contactors are closed and when this
circuit is closed the solenoid (#28 onpls. 7-14) is energized
to position a flpo,{er-failure ltvalve of the control system. See
references in the circuit description.
41. A-end assemb ly.- The A-end assembly of the power
plant (d.r. no. 274247) is a unit of commercial design and manufacture
(Vicker's). It operates to provide pressure oil to
drive and control the B-end and its coupled hoist drum (also
of Vicker's manufacture). The unit includes a variable delivery,
seven cylinder, piston type of pump, which is mounted
in a steel housing. On the top of this housing is located a
train of gears and a mounting face for the control and supercharging
pump_ The centering spring assemblies, .which return