large stationary rectifier vs. individualized units? Plz help

[mikewilson7]

Here's the scenario: I have 5 E.O.T. cranes, none of which are used for production, intermittent maintenance only. Each crane draws no more than 400 amps peak (inrush) when running all 3 motions simultaneously(bridging, trolleying and hoisting). All are 250V DC, fed by an aging rectifier (located in a centralized area) which is grossly oversized for its current load (utilizing about 10% of its rated output). Other than the cost incurred by replacing the 2 rail dc feed with a 3 phase rail feed and installing individual rectifier units on each crane, are there any other factors I should take in consideration before undergoing such a project? Any suggestions or insights are welcome!!

 

[ScottyUK]

You already own the existing installation: if there is nothing wrong with it other than it being oversized, why are you replacing it?


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One day my ship will come in.
But with my luck, I'll be at the airport!

 

[jraef]

I think ScottyUK's point is sound. To add to it, adding more components increases the risk of failure somewhat. WHEN the existing system fails, then it might be worth considering if there is some other benefit to be gained. But for an occasional use system like that, I wouldn't change it much at that time either, maybe just a smaller central rectifier. Spend those budget monies elsewhere.

If on the other hand the existing system is giving you inconsistant performance or is prone to not being available when you need it, then I would consider what you are speaking of, but just replace all of your crane drives with the most up-to-date DC drives you can afford.

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