[Varley]

Employ more cleaners!

I have never worked and CAD/CAM simply the resultant drawings sent for approval. One thing that perhaps some cut down version might do is also what employers of the PLC could do but I have not seen in the marine environment. Simulation. Both as an designers/approvers aid (I assume lots but not all errors are excluded by the design software) and for the operating technicians. If one has the logic existing as software rather than electromagnetic relays it is only a small (cheap) step to copy that so one can 'fault' it for comparison. For fun (no director can read this and weep now) I recreated the logic of a switchboard (the same as in the St.Lawrence grounding 'above') in an HP85 and Basic using statements along the lines of [RLA1= (RLA10 and not RLA20) or not RLA23 etc. straight off the circuit diagram and running it in a loop until no changes were detected, replacing the real element with 0 or 1 to simulate the failure mode]. This 'discovered an interesting mode whereby the low frequency trip relay failure could cause a chain of blackout, auto start&connect of standby repeating. I got to try this out on a ship visit but the chief chickened out after the second blackout.

Clients in better served industries (for instance nuclear, oil and gas, public transport etc.) expect the automation of their new installations to have been and fully tested against a virtual plant. The specialist contractors serving those industries serve us as well and know the SP. We are short changed.