Transport And Storage of Siemens Generator

3. Transport and Storage of Siemens Generator/Alternator

3.1 Safety advice

The openings, lifting eyes and hoisting lugs on the base-plates are used for transporting the machine sets. The sets must not be lifted by attaching ropes to the individual machines. Take account of the carrying capacity of these hoisting devices.

Individual machines must only be suspended on the main lifting lugs or recesses. The hoisting gear used  must be designed in accordance with the weight. Use suitable rope guiding or spreading devices for avoiding damage to machine-mounted accessories.

Auxiliary lifting lugs, e.g. on fan cowls, top-mounted heat exchanges etc, are not designed for carrying the machine weight. They are only suitable for lifting the respective individual part during dismantling and assembly.

3.2 Storage and conditions

The generator and accessories must be stored in the proper manner until they are installed, and protected against moisture, dirt, various chemical substances, living creatures liable to cause damage and all other kinds of extraneous influence. If the generator is contained inside a shopping crate, is must be removed there from.

The store-houses have to be clean, dry, closed and free of vibration. The temperature should not drop under +5°c.

3.3 Checks during storage

If the machine is stored for longer than three months, the insulation resistance and the preservative coatings must be checked. If the insulation resistance falls below the value specified in section 4.3.1, Table 1, the generator must be dried immediately. 

4. Mounting and operation

Strictly observe the "General safety instructions" in Section 1.2 regarding the permissible use of the machines, as well as the special knowledge required for carrying out work on power installations.

Covers to prevent accidental contact with live or rotating parts, and those required for proper air guidance and thus effective cooling should not be opened during operation.

An appropriately designed control and speed monitoring device must ensure that no higher speeds are attained than those permitted according to the rating plate.

4.2 Preparation

4.2.1 General visual inspection of the machine

The generator must be subjected to a thorough visual inspection before it is mounted, to ensure that it has not suffered any damage in transit or storage. Any defects which are detected must be notified to the supplier or shipping agent and remedied expertly. 

The condition of the insulation must be checked.

4.2.2 Position

The generator must be positioned so that the terminal box, the bearings and the accessories are easily accessible.

4.2.3 Mounting

The generator must be mounted on a firm foundation. The feet must be mounted on a level metal base. The supporting surfaces must be carefully packaged if necessary, to ensure that the stator frame is not deformed.

4.2.4 Cooling

The room containing the generator must be sufficiently large and well-ventilated. Steps must be taken to ensure that the generator does not take in the hot air exhausted by other machines.

CAUTION: Temperature up to and exceeding 100°C may arise under unfavourable operating conditions on the frame parts so that touching should be prevented or avoided in this case. Temperature-sensitive parts such as normal cables or electronic components should not be in contact with or mounted to these hot parts.

4.2.5 Coupling

A flexible coupling must be used to couple the generator mechanically to the prime mover. The coupling must be dynamically balanced and capable of transferring the torque without generating rotary forces that could act on the generator, the coupling must not transfer any harmful forces or shocks to the generator.

Before the coupling is mounted on the generator shaft, the preservative coating must be removed and the shaft coasted instead with a thin layer of oil. No force must be used to mount the coupling on the shaft. A fitting device with a thread corresponding to that of the generator shaft is useful, or alternatively the coupling can be heated to appropriately 100°C in an oil bath.

An extraction tool must be used to remove the coupling from the shaft.

The generator must be aligned with the aid of two dial gauges. It is advisable to keep well within the tolerances specified by the coupling manufacturer if possible, as any misalignment will cause an additional load to be placed on the bearing and the coupling. 

4.2.6 Securing the mechanical position

When the generator has been mounted and fastened to the base, its position must be secured so that the shaft alignment cannot be altered during operation. It is advisable to pin the feet at the base.

4.3 Connections

4.3.1 Insulation resistance of the winding

The insulation resistance of the stator winding must be measured before a new generator or a generator which has been out of service for a long time is put into operations. If the winding is in perfect condition, its resistance must not be less than the values specified in Table 4.3.1 a.

WARNING During and immediately after measuring the terminals may in part carry dangerous voltages and must not be touched.

Should any power supply cable be connected, ensure that no system voltage can be applied. 

Table 4.3.1 a

1) Lowest measurement voltage 100V

The insulation resistance must be measured for roughly one minute until upper range value is reached. If the measured resistance is less than the value specified in the table, the generator must be dried. If the winding temperature rises by 10°C, the insulation resistance drops by appropriately half. If the temperature of the winding drops below 5°C, the measured insulation resistance may be misleading and must not be used to determine the readiness of the equipment for connection.

4.3.2 Drying

The simplest drying method is a dry room containing clean air heated ro 80°C and a steam exhauser. In this case, the generator does not need to be dismantled. If the generator is designed with a higher degree of protection, e.g. IP 54, the parts which provide this protection must be removed. The drying time depends on the amount of moisture.

Other drying methods:

-Short-circuit operation

-Heating with direct current

This insulation resistance must be measured during the drying process. It drops abruptly initially and then rises again gradually. The generator is dry when the insulation resistance reaches the specified value.

If the insulation resistance of the generator still does not improve after a long drying period, the low insulation value must caused by another type of fault and nor by moisture in the stator winding.

The cables must always be laid to the generator. And the generator connected to the switching and protective devices, by suitably qualified persons. These persons must observe the valid specifications and standards in doing so. The cables must connected correctly and exert neither a tensile nor a flexural stress on the terminals.

The cables must be connected in according with the circuit diagram on the inside of the terminal box cover. The terminal screws must be properly tightened, so that they cannot be heated up and loosened during operation as a result of a contact resistance.

The terminals box must be closed after the connections have been made.

4.3.3 Fuse protection

The generators must be protected by means of fuses which are suitable for the rated current specified on the rating plate.

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