Page 77 - Offshore Electrical Engineering Manual

64 CHAPTER 4 Prime Mover Selection Criteria

100 PO
40 OHMS
100 A for 30 sec
4A continuous
101

Protection and
instrumentation
2.6 MW 3.25 MVA
0.8 PF X’d = 15%

102

Protection and
instrumentation

630 A
E
EB
SYN EC 1250 A
L2
L1 S
EC SYN
FIGURE 2.4.4
Medium-voltage resistance earthed arrangement.

it became necessary to fly a small generator set or compressor out to the plat-
form in order to restart generators and hence continue the output of oil from the
installation.
Maintenance must also be catered for in starting facilities such that whilst part of
the system is being maintained, there is still at least one method of black start open to
the operator. An example of this would be the need to allow for planned or unplanned
outages in the emergency switchboard whilst still providing electrical supplies to
main generator facilities, such as engine cranking motors and lube oil auxiliaries; a
provision which has often been overlooked in the past.