Manual for Induction Motors and Generators
Maintenance -
87
3BFP 000 050 R0101 REV E
If the winding or cooling air temperature detectors show an abnormal temperature, a check of
the cooling system has to be made. The two maintenance issues are to check the condition of air
filters and to ensure good air circulation inside the machine. The machine interior should be
cleaned and checked during overhauls or if problems arise.
Other possible causes for poor cooling system performance might include elevated ambient
temperature or high intake air temperature. In addition, lubrication or bearing malfunction
might lead to high bearing temperature.
A seemingly high temperature might also be caused by a problem in the temperature
measurement system
Chapter 8.3.2 Pt-100 resistance temperature detectors
7.8.1.1 Cleaning of filters
The filters should be cleaned regularly. The cleaning interval depends on the cleanliness of the
air in the surrounding environment. The filters have to be cleaned when the temperature
detectors in the winding show abnormal temperature or approach the alarm level.
If a filter differential pressure monitoring system is being used, the filters should be changed
immediately after a pressure alarm. The alarm level is such that 50% of the air filter surface is
obstructed. The operating personnel should also manually inspect the filters frequently.
Remove the air filters for cleaning. If the surrounding air is sufficiently clean, the filters can be
changed during operation. They should regularly be cleaned by vacuuming first from the
upstream side, then on the discharge side. Periodically, a thorough wash with clean water is
recommended to release any dirt not removed by vacuuming. When heavy grease
concentrations are encountered, the filters should be washed with a detergent solution. This
solution should be rinsed thoroughly before returning the filter to service. Be careful to install
the air filters in the correct direction, i.e. the arrows on the air filter frame indicate the direction
of airflow. Some filters can be installed in either direction. Refer also to the air filter
manufacturer information.
***Following chapters for cooling type: Air-to-water
7.8.2 Maintenance instructions for air-to-water heat exchangers
If the temperature detectors show normal operating temperature, and the leakage detectors
indicate no leaks, usually no additional supervision is required for the cooling system.
***Following chapters for cooling type: Air-to-air
7.8.3 Maintenance instructions for air-to-air heat exchangers
The cooling unit is installed on the machine. The air tubes in the heat exchanger are normally
made of Aluminium.
7.8.3.1 Air circulation
The inner air is normally circulated by a fan and/or by the rotor. The fan may be mounted on the
shaft or driven by a separate motor. Depending on the machine design, the circulation may be
axially symmetrical or asymmetrical.
The outer air flow is normally created by a fan, mounted on the shaft or driven by a separate
motor. Connection to external air pressure is also possible.
