Commissioning and Maintenance of Siemens Generator

4.4 Commissioning and operation of Siemens generator (alternator)

4.4.1 Commissioning

The following checks are essential before the driving machine is commissioned;

- The generator load must be disconnected.

- the insulation resistance must have at least the specified value.

- All the safety rules for operation of the generating set must be observed.

- The protective earth conductor must be connected. 

After these checks, the complete generating sets can be started up in the accordance with the instructions.

Providing the generator has not been out of service for more than three months, a brief visual inspection is sufficient before is started up again.

4.4.2 Changing the direction of rotation

The generator is equipped with one fan for both directions of rotation. If the direction of rotation is changed, the phase sequence at the main terminal is also changed.

4.4.3 Operation

Note: Deviations from the normal performance (higher power input, higher temperatures of vibrations, unusual noises or odours, reactions by monitoring equipment etc.) indicate that proper function of the unit is impaired. In order to avoid faults, which might directly or indirectly cause serious damage to property or injure to persons, the responsible maintenance personnel must be notified immediately.

The generator is excited automatically. The following points should be noted:

 - The desired terminal voltage can be set with the potentiometer as soon as the rated speed is reached.

- The generator can be fully loaded as soon as the rated speed is reached.

The following operation data must be checked:

- The current, to ensure that the generator is not overloaded.

- The load balance of the individual phases.

- The frequency.

- Heating of the bearings, cooling of the machine and mechanical running.

In order to avoid resonance phenomena, it is important to ensure that the natural electromechanical frequencies of the generator do not coincide with the mechanical excitation frequencies of the prime mover.

4.4.4 monitoring during operation

The generator functions must be monitored during operation to ensure that they are not impaired by faults. Any defects which are detected must be remedied immediately. In particular, the cleanliness of the generator, the load as specified on the rating plate, smooth vibration-free running, the perfect condition of the bearings and the tightness of the terminals must be checked. If the generator has been out of service for a long time, the insulation resistance of the windings, the conditions of the lubricant in the bearings, the tightness of the terminal screws and the mechanical coupling to the prime mover must be checked before is started up again.

4.4.5 Taking out of service

The load must always be disconnected before the generator is shut down. The procedure described in the instructions for the complete generating set must then be followed.

5. Maintenance

5.5 Safety advice

Before any work is started on the machines, particularly before covers are removed from live parts, make sure that the machine/plant has been correctly disconnected from the supply. This applies both to the main circuits and to anti-condensation heating circuits!

Please adhere to the general “5 safety rules” (e.g. to DIN VDE 0105):

- Isolate the equipment from the supply.

- Provide a safeguard to prevent unintentional reclosing.

- Verify safe isolation from the supply.

- Earth and short-circuit (with voltages above 1000 V.)

- Provide batteries or covers for adjacent live parts.

Caution: Special designs and model variants, however, may differ from the normal drawings in technical details. In the case of any uncertainties, we urgently recommend inquiry at the works giving the machine type and serial number or to have the maintenance work performed by one of the SIEMENS service centers.

Warning: All work on the generator, other than relubrication of the bearings, must be observed at all times. If work must be carried out on current-carrying machine parts or on accessories, the generator must always be disconnected from the power system and the current-carrying parts must be checked to ensure that they are no longer live. The protective earth conductor must always be connected.

5.2 Checking the condition of the insulation

The condition of the generator insulation must be checked as described in section 4.3.1 whenever maintenance work is carried out the machine is started up again after a long period out of service.

5.3 Cleaning

The generator and accessories must be kept in clean condition to the operating conditions.

The best cleaning method is with dry compressed air (up to 200 kPa). Accumulations of dust will impair the cooling efficiency of the machine and cause it to heat up more.

If the generator is equipped with a filter at the cooling air inlet, it must be cleaned regularly. The cleaning intervals are dependent on the environment in which the generator is operated. The lever of the contamination can be assessed on the basis of the temperature of the stator winding, which incorporates a resistance thermometer as standard in all the models fitted with filters. The filter must be purged with compressed air after it has been removed.

Warning! Use personal protective equipment (e.g. protective goggles, breathing mask etc.) and appropriate dust exhausting gear when cleaning with compressed air.

If chemical cleaning agents are used the warnings and be observed. Chemical agents must be compatible with the materials used, especially plastics.

5.4 lubrication of the rolling-contact bearings

The generator is equipped with rolling-contact bearings , which are pre-filled with lubricating grease and ready for operation immediately. The bearing type and the approved grease type are specified on the instruction plate at each lubrication point. In these standard construction the bearings are preloaded. Generator types 1FC2 18 to 1FC2 35 are fitted as standard with bearings that have been pre-lubricated for life. The 1FC2 35 generator can be optionally fitted with a pre-greasing device and a grease slinger (additional charge), while the 1FC2 45 and larger generators are equipped with these components and standard. Each time the generator is serviced, the bearing cartridge must be cleaned and filled with new grease. Generator type 1FC2 45 and larger can be supplied with sleeve bearings on request. An addendum to the instructions is enclosed with these models.

5.5 Replacing the grease in the rolling-contact bearings

The grease in the rolling-contact bearings must be checked regularly and replaced if necessary.