Page 38 - Handbook of Electrical Engineering

ESTIMATION OF PLANT ELECTRICAL LOAD 17

• Fuel availability, rates and calorific values, pollution components e.g. sulphur, carbon dioxide,
alkali contaminants, particle size and filtration.
• Electrical heating and refrigeration loads, trace heating of vessels and piping.
• Make available process flow diagrams, process and instrumentation diagrams, utilities and instru-
mentation diagrams.

1.8.2 Mechanical Engineers

The mechanical engineers will normally need to advise on power consumption data for rotating
machines, e.g. pumps, compressors, fans, conveyors, and cranes. They will also advise the power
output options available for the different types and models of prime movers for generators, e.g. gas
turbines, diesel engines, gas engines.
In all cases the electrical engineer needs to know the shaft power at the coupling of the
electrical machine. He is then able to calculate or check that the electrical power consumption is
appropriate for the rating of the motor, or the power output is adequate for the generator.

The mechanical engineer will also advise on the necessary duplication of machinery, e.g.
continuous duty, maximum short-time duty, standby duty and out-of-service spare machines. He will
also give some advice on the proposed method of operation and control of rotating machines, and
this may influence the choice of cooling media, construction materials, types of bearings, ducting
systems, sources of fresh air, hazardous area suitability, etc.
The electrical engineer should keep in close ‘contact’ with the progress of machinery selection
during the early stages of a project up to the procurement stage in particular, so that he is sure the
electrical machines and their associated equipment are correctly specified. Likewise after the purchase
orders are placed he should ensure that he receives all the latest manufacturers’ data relating to the
electrical aspects, e.g. data sheets, drawings, changes, hazardous area information. See also Chapter 19
and Appendix E.

1.8.3 Instrument Engineers

The process and instrument engineers will generally develop the operation and control philosophies
for individual equipments and overall schemes. The electrical engineer should then interface to enable
the following to be understood:

• Interlocking and controls that affect motor control centres and switchboards, generator controls,
control panels, local and remote stations, mimic panels, SCADA, computer networking, displays
in the CCR and other locations.
• Cabling specifications and requirements, e.g. screening, numbers of cores, materials, earthing,
routing, segregation and racking of cables.
• Power supplies for control systems, AC and DC, UPS requirements, battery systems.
• Symbolic notation, e.g. tag numbers, equipment names and labels, cable and core numbering
systems.