Our plant unfortunately has some reasonably long motor cables (up to 800 m) for motors in the range of 30 HP to 100 HP resulting in quite large motor cables. Can anyone point me to a source for maximum cable termination sizes for IEEE 841 motors within this range? I am estimating the number of...
You guys onshore have no idea, in offshore you get all sorts of voltage/frequency combinations and earthing arrangements. Through a process of design by committee we ended up with a 60 Hz system with 11 kV, 6.6 kV, 440/254 V, 230 V (UPS) and 110(55-0-55) V. We started with a 50 Hz system with...
Low resistance earthing is characterized by placing one or more NERs between the system neutral and earth, restricting potential E/F current to a medium magnitude in the order of 200 A, but typically no more than 1000 A.
The reasons for limiting the current by resistance earthing include:
•...
Alex,
Thanks for your reply, I realise my query is quite vague, unfortunately I'm in the position that I can't approach vendors for commercial reasons. My colleagues in the mechanical group are going through vendor pre-qualification at the moment. The European Union rules on fair competition...
I am in the process of developing a preliminary power system model for a new oil platform using the power system analysis package ERACS. As part of this model I'm looking to perform motor starting studies, which will require me to model the mechanical loads being driven by motors. Can anyone...
I'm investigating methods of managing fault level on an offshore installation with approximately 3 x 40 MW gas turbine generators. One option I am considering is increasing the sub-transient reactance of the turbo-generator.
In speaking to turbo-alternator manufacturers, their basic response...
The custom impedance generator sounds like a good option, but I've also heard some switchgear manufacturers have tested 50 kA switchgear to higher fault levels. Whether they're prepared to issue type test certificates is another question.
There is some opposition to a 60 Hz system, this is an...
I'm looking at possible designs for the distribution system of a new offshore installation with a maximum load of 70 MW supplied by 3 x LM6000 42 MW GTs. This immediately presents a problem of available switchgear fault and normal current ratings, with typical metalclad switchgear restricted to...
