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 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.
4.3.15.1 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 with 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.
4.3.15.2 Inspections Made with Power On. Close the mainline switch and proceed. Observe the
operation of the control equipment when the dumbwaiter is run in each direction. Note any
arcing of contacts, excessive heating of coils or resistances, and misalignment of relays,
contactors, and switches. Dumbwaiter 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.
4.3.16 Machine Room
Check the machine room for the following:
a. Adequate lighting.
b. Housekeeping and the presence of any flammable liquids (flash point less than 110 degrees
F) or materials not necessary for the operation and maintenance of the elevator.
4-28
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