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 the generator-field control system, are not considered to be part of the hoist equipment.
9.6.16 Control Equipment
The following inspection procedure applies to all the control mechanisms, including starting
panels for motor-generator sets that are part of the hoist control system, signal panels, hoist
controller panels, dispatching panels, selectors, etc. A good preventive maintenance program
on the control equipment will greatly reduce shut downs. Many controllers have pieces of
rotating equipment that are part of the controller and that are applied in various functions. These
should not be overlooked. They should be given the same type of inspection as the larger
rotating equipment.
9.6.16.1 Inspection Made with Power Off. Open the mainline switch and examine all relays,
switches, contactors, control circuit rectifiers, transformers, capacitors, reactors, vacuum tubes,
etc., and note:
a. Any excessively worn or burned contacts broken connectors, broken or cracked resistance
grids or resistance tubes.
b. Any fuses which are shorted with wire, solder or metal strips.
c. Whether the equipment is clean.
d. Any accumulation of combustible materials especially on resistance grids or wires, or on
control circuit rectifiers (a common cause of fire).
e. Whether contacts of reverse-phase relay, where provided, are open.
f. Excessively worn pin hinges on relays or contactors.
9.6.16.2 Inspections Made with Power On. Close the mainline switch and proceed. observe the
operation of the control equipment when the dumbwaiter hoist is run in each direction. Note any
arcing of contacts, excessive heating of coils or resistances, and misalignment of relays,
contactors, and switches. Hoist performance must also be checked and compared with previous
test data and criteria. This would include door operation, acceleration, deceleration, and floor
stopping accuracy. This will determine if the system is operating at its full potential or if
adjustments are needed to obtain a system operating at design capabilities. Unusual noises
should also be noted.
9-15
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