Page 294 - Offshore Electrical Engineering Manual

Motors and Generators 281

Protective films on machined surfaces should be cleaned off with the recom-
mended solvent. This cleaning should take place just before installation, where
plinths are in contact with baseplates etc., and before commissioning for items such
as motor shafts. Shafts and bearings need to be kept clean and covered whenever
work is not proceeding.
Shims supplied with the equipment should be used wherever possible for level-
ling. Shims should be of similar area and shape as the machined surfaces of equip-
ment footings they are used for, and the maximum thickness of shims should always
be used so that the minimum number of shims is positioned under each footing.
Where separate bearing pedestals are supplied, these should be positioned, levelled
and lined up before the installation of other machinery components.
White metal bearings should be checked to ensure adequate bedding using engi-
neer’s blue or some other suitable method of indication.
Coupling faces should be truly parallel and level. This will need to be checked
with each shaft rotated to several different positions.
Coupling bolts or flexible connections should be properly fitted without damage
and all nuts tightened and locked before running the machinery.
When larger machines, particularly synchronous machines, are installed, the
manufacturer’s instructions concerning insulation must be carefully followed to pre-
vent circulating currents flowing in the machine frame. Where the machine frame is
installed in sections, conductive bonding between each section will need to be estab-
lished, if necessary, by separate bonding conductors. This is particularly important
when the motor is sited in a hazardous area, otherwise sparking may occur between
sections.
The larger heavier machines should be provided with permanent runway beams
and horizontal and vertical screw jacks to facilitate alignment.
Alternatively, suitable jacking points can be provided for temporary jacks. The
use of block and tackle arrangements or tirfors is time consuming and likely to
increase the risk of injury to installers.
Before commissioning, machines should be cleaned, and if of the open type, dust
and dirt should be blown out. Commutators and slip rings will need to be checked for
deterioration during transit and storage and, if necessary, cleaned. Carbon brushes
will need to be checked for freedom of movement, and springs checked for correct
pressure.
If machines have been stored for a long period, the bearing grease should be
inspected and if deterioration has occurred, the bearings should be thoroughly
washed, dried and regreased using methods recommended by the particular bear-
ing manufacturer. Where oil lubricating systems are employed, bearing oil rings,
flow switches, pressure switches, pumps, etc. must be checked to ensure they are
fully operative before any running of the machine is attempted. Machine shafts
will require to be rotated by hand or barring gear to ascertain that no foreign body
is either inside the machine or between the external fan and its protecting cowl.
Checks should also be made to ensure that ventilating air ducts are clean and clear
of obstruction.