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Long lead time on X1 Capasitors

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PetrosA:
I recently read an article about long lead times for lighting fixtures here in the US. Evidently it's mostly the specialty high efficiency stuff with electronic transformers/ballasts required by new laws in commercial/industrial settings that are affected and the problem is bad. Contractors are bidding jobs and can't get the fixtures in time to meet the deadline. Supposedly the problem is that a large number of small electronic component manufacturers went out of business during the peak of the economic crisis and the big players slowed down production to the point where now they can't keep up. Some suppliers claim the lead time is better than it was - down from 8-12 weeks to 6-8 weeks, but still way too long for bid projects.

I don't know if you'll be able to read this without being logged in, but here's the article:

http://ecmweb.com/lighting/ballast-shortage-20110201/

Bloch:

--- Quote from: PetrosA on April 09, 2011, 02:52:03 am ---economic crisis
--- End quote ---

Thank you for the link.

First economic going to fast then slow and now faster again.

Why is that my problem  ???  ;D

Zero999:

--- Quote from: RayJones on April 08, 2011, 11:53:52 pm ---Is there any problem in using a few hundred K in parallel with the caps for the express purpose of load balancing?

That's what we were taught way back.

--- End quote ---

That works better with DC than AC. For DC, the divider just needs to draw a bit more current than the leakage through the capacitors so very high value resistors will do. With AC, the resistors still need to have a lower impedance than the capacitors but it's much lower with AC flowing through them. In this case 220nF capacitors (required for just over 100nF when connected in series) have an impedance of 14.5k at 50Hz so resistors with and lower value would dissipate too much power.

alm:
You'll also have to make sure that your resistors are specified for the working voltage and transient voltage, and will fail safely.

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