Page 293 - Offshore Electrical Engineering Manual

280 CHAPTER 1 Installation Practice

Having opened and closed all the circuit breakers electrically, a start can be made
on primary injection testing of relays, and megger and high-voltage insulation checks
completed, as these are more easily carried out before any cabling work commences.
Before any incoming or supply cables are connected, all the required earthing
copperwork and cabling should be completed and tested.
The switchboard should now be ready for connection to incoming supplies.
Cabling checks are discussed in a later section and commissioning is discussed
in PART 7 Chapters 1–5. Having energised the switchboard, contactors may be
checked for electrical operation. Supply circuits are then commissioned on a piece-
meal basis as part of the commissioning procedure for the item of equipment being
supplied.

DISTRIBUTION TRANSFORMERS
Distribution transformers are heavy devices and it may have been necessary to
strengthen a particular section of the module floor or platform deck at the installa-
tion site. The installer should ensure that all transformers are placed on a flat, level,
previously prepared base, in the location shown on the relevant design drawing. Once
installed, it may be necessary to fill the transformer if it is a fluid-filled type. Some
types of insulation fluid are toxic and therefore special precautions will need to be
taken.
The manufacturer’s representative should be called in after all the transformers
have been located and filled, to assist and witness the final checking and testing.
Insulation tests should then be completed, and after cabling, a second insulation test
of all windings and connections should be carried out. On installations having two or
more transformers connected to a single switchboard, a phase polarity check should
be carried out across the associated bus section.

MOTORS AND GENERATORS
In most cases, rotating machinery will be installed as a complete skid-mounted
package. Whether installed as separate items or not, great care must be taken to
ensure that the motor and driven machinery are correctly located and aligned after
installation. The equipment must be slung or lifted from the prescribed lifting posi-
tions such as eyebolts where these are available. A normal rule of thumb is that the
lifting orientation of the machinery should be identical to its operating orientation,
i.e., normally lift in the upright position.
During the entire installation procedure, it is important to use any tools or mate-
rials supplied specifically for the installation of the particular machine. It is not
uncommon for such items to be left in the equipment packing case or otherwise over-
looked and for installation to then go ahead using improvised methods which may
jeopardise the success of the project and possibly the safety of offshore personnel.