When the system is engineered, the actual position of each component part will dictate the arrangement of wiring, piping and general services, etc. The engineer will need to divide the work according to the scale of the contract and define which diagrams are necessary.
A production circuit diagram for an electrical control panel would show how the panel was built, with all the necessary line and neutral wiring connections in their exact places together with earth links. An exact construction record is essential for service requirements. Wiring must be sized. Standards for current capacity dictate the wire dimensions. Wires are often colourcoded to facilitate tracing. Wires are run singly, in multicored cables, in looms and conduits, inside and outside and in almost every conceivable ambient situation.
The following electronic diagrams include symbols from BS 3939 and the extracts from BS 5070 are given by kind permission from British Standards. Note the clear, accurate and presentable layout which is essential in the production of engineering diagrams. Clarity depends on sufficient thought being given to spacing not only the symbols but associated notes and references.
Figure 27.2 shows a thyristor control system.
Part (a) outlines the basic blocks.
Part (b) provides added details to the four parts.
Part (c) gives the component connections for the zero voltage trigger with waveforms at various points.
Part (d) is an example of a supplementary diagram where the waveforms are related to a common datum.
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