Three-phase squirrel cage induction motors in flameproof enclosure type ASA and E2-ASA
frame size 63 – 355
Especially for motors intended for the use in Zone 21 or 22, to avoid
unpermissible surface temperatures, there is to consider the maximum
thickness of dust layers upon the machine surface (maximum 5 mm) and
the free air inlet for the cooling system.
Bearing appropriate functioning requires clean mounting places, free of
dust or other contaminants, using of proper mounting tools, recommended
lubricants.
The motors of frame size 280-315 have a greasing system enabling the
bearings to be lubricated during the operation.The bearing relubrication
intervals and quantity of grease are shown in the
Table 4.
To relubricate the regreasable bearings use UM 185 Li3, Shell Alvania
R3, SKF LGTH3, UTJ 185 Li2/3, UNIREX N2 or similar (the grease type is
given on the motor rating plate)
In case of damaging, the sealed bearings should be replaced with
similar ones.
Before remounting the surface of the shields coming in contact with the
housing should be cleaned and covered with a thin layer of anti-rust grease
The insulation resistance should be periodically checked; a value under
1 M
Ω
warns that a damage caused by dirt deposits on the insulating
surfaces or moisture penetration in the stator winding can occur. Clean the
winding and dry it in accordance with par. 6.2.3
NOTE: When servicing a three-phase motor, it is generally not necessary
to dismount it. The motor has to be dismounted only if the bearings need to
be replaced
–
Initial inspection
– the first inspection after commissioning or repair of
the three-phase motors is carried out after about 500 operating hours, but
at the latest 6 months. While the motor is running check that:
-
the allowable bearing temperature is not exceeded
-
the motor electrical parameters conform to those on the rating plate
With the motor at standstill, check the foundation and assembly bolts
condition: lack of cracks, indentations, signs of wear
NOTICE: Any inadmissible deviations from these requirements which
are detected during this inspection must be immediately eliminated
-
Main inspection
(motor thoroughly examination) - Yearly
While the motor is running:
-
check the bearings if the permissible temperature is not
exceeded;
-
check that the motor electrical parameters are within the
permissible tolerance limits
