Component location discussion
When designing the electrical distribution / raceway system for a plant, an electrical engineer will normally have process, mechanical and civil engineering information available. This information informs the electrical engineer where electrical components can and in many cases must be located. Some examples:
Several instruments taps and a valve have been located, by a process engineer, on a pipeline.
The electrical engineer must locate a junction box near the instruments (and valve) to supply power for these devices and also connect control and signal lines to any central control system. The electrical engineer should also place a motor, solenoid or other actuator near the valve. The engineer should also place instruments on the instrument taps.
A pump and fan have been placed in a plant by a mechanical / process engineer.
The electrical engineer must place the electric motors and control panels for these devices in the plant. Field switches such as emergency stop buttons, photocells and limit switches must also be placed in the plant.
The civil / structural engineers have located an area for use as a substation / analyser shelter / control room or similar.
The electrical engineer must place transformers, distribution panels, DCS panels and analysers into these structures. The layout is usually flexible.
As the electrical engineer does not layout the process and mechanical parts of a plant, much of the electrical layout (e.g. positions of electrical components) is pre-defined and all you need do is decide their specifications and place them at the required locations. In other instances e.g. distribution transformers, control room panels and distribution panels you are given an area and you may decide the positions and specifications of these components.
You cannot lay out raceway until you know where all raceway components are to be located. This implies you must have prior knowledge of the civil / structural details of the plant.
If it is possible to import or XREF (AutoCAD XREF) a civil / mechanical / process model to your model, it is worth doing. The existing layout will assist you to position components. If not, you will need to study and record any positions that have been dictated to you by other disciplines.