Table of Contents
Advertisement
7.4.4 The tightness of fastenings
The tightness of all fastenings should be verified regularly. Special focus should
be given to fixing and the rotor parts, which must remain correctly tightened at all
times. Loose fastening in these parts can lead to sudden and severe damage to the
entire machine.
General values for tightening torques are presented in Table 7-10. General
tightening torques.
Table 7-10. General tightening torques.
Screw
NOTE: The values in Table 7-10. General tightening torques are general, and do
7.4.5 Rotor construction control
Particular attention should be paid to rotor construction, because even small
damages in the rotor can lead to severe damages in the stator. In addition,
mechanical problems in the moving parts such as the rotor have a tendency to
develop faster than in the stationary parts of the machine.
Therefore, rotor construction should be checked yearly, preferably using an
endoscope and ultrasonic equipment. The condition and tightness of the fastenings
should be checked carefully.
7.5 Maintenance of bearings
Bearings are either re-lubricated or closed antifriction bearings without re-
lubricating possibility. Calculated bearing lifetime is mentioned in the technical
specification. Actual lifetime of the bearing depends however heavily on the
operating conditions and calculated value shall be only used as a guideline.
The lifetime of the DE- and NDE-bearings without re-lubricating option is
sometimes likely to be shorter than the lifetime of the electrical machine.
Therefore, the bearings could be changed sometimes. The maintenance of rolling
bearings requires special care, tools and arrangements as to ensure a long lifetime
of newly fitted bearings. During bearing maintenance, ensure that:
•
No dirt or foreign debris is allowed to enter the bearings at any time during
the maintenance.
Screw torque
4.8
Tightening torque [Nm]
M8
10-12
M10
20-25
M12
36-45
M14
55-70
M16
90-110
M18
120-150
M20
170-210
M22
230-290
M24
300-375
M27
450-530
not apply to various items, such as diodes, support insulators, bearings,
cable terminals or pole fastenings, surge arrester, capacitors, current
transformers, rectifier and thyristor bridges, or if some other value is
given elsewhere in this manual or in the mechanical and electrical
drawings, see Mechanical drawings and Electrical drawings.
Page 46
Property class
8.8
22-30
30-35
45-60
65-80
80-105
110-130
125-165
180-210
195-265
280-330
265-355
380-450
375-500
540-650
515-680
740-880
655-870
940-1120
955-1270
1400-1650
10.9
Advertisement
Table of Contents
