Handbook of Electrical Engineering

ESTIMATION OF PLANT ELECTRICAL LOAD 7

This in turn will enable an initial layout of all the facilities and equipment to be proposed. Since this is
a new plant and the preliminary data is estimated from process calculations, mechanical calculations
and comparisons with similar plants, it is acceptable to use the following diversity factors,Dc= 1 .0,
Di= 0 .5andDs= 0 .1.

Tables 1.5, 1.6, 1.7 and 1.8 show the individual loads that are known at the beginning of
the project.

The total power is found to be 12,029 kW. At this stage it is not known whether the plant is
capable of future expansion. The oil and gas geological reservoir may not have a long life expectation,
and the number of wells that can be accommodated on the platform may be limited. The 4000 kW
of power consumed by the drilling operations may only be required for a short period of time e.g.
one year, and thereafter the demand may be much lower.

Table 1.7. Subsidiary load schedule for the low voltage emergency switchboard

Description of load No. of
units

Nameplate

ratings of

each unit

(kW)

Continuous

power

consumed

(kW)

Intermittent

power

consumed

(kW)

Standby

power

consumed

(kW)

Emergency lighting 1 75 75 0 0
Chlorine generator 1 ∗ 30 30 0 0
Desalination unit 1 ∗ 75 75 0 0
Potable water pumps 1 5 5 0 0
Instrument air compressors 1 90 90 0 0
Instrument air driers 1 10 10 0 0
Living quarters feeder-B(off) 1 ∗ 500 0 0 0
Living quarters emergency feeder 1 100 50 50 0
Living quarters hot water pumps 1 15 15 0 0
Diesel fuel transfer pump 1 5 5 0 0
Emergency diesel eng. sump heater 1 3 3 0 0
Emergency diesel gen. auxiliaries 1 2 0 0 2
Emergency diesel eng. bat. charger 1 1 0 1 0
Emergency diesel eng. room fans 2 11 11 0 0
Control room fans 2 22 22 0 0
Computer UPS supply 1 5 5 0 0
Emergency radio supplies 1 10 0 0 10
Navigation aids UPS supply 1 10 10 0 0
Life boat davit supplies 2 37 0 50 24
Life boat diesel heater supplies 2 4 4 4 0
Fire pump engine battery chargers 2 22 22 22 0
Seawater washdown pump 1 ∗ 37 0 37 0
Anti-condensation swbd heaters — 25 25 0 0
Anti-condensation motor heaters — 25 10 15 0
Portable lighting supplies 1 1 1 0 0

Sub-totals for the switchboard 468 179 58
Normal running load for the switchboard=( 1. 0 × 468 )+( 0. 5 × 179 )+( 0. 1 × 58 )=563 kW

For black start delete loads marked (∗)

Black start sub-totals for the switchboard=( 1. 0 × 363 )+( 0. 5 × 142 )+( 0. 1 × 0 )=434 kW