Do I need to Test for Harmonics?

[Scott Douglas]

Fellow Listees:

There were some recent threads regarding what testing is required for a product that obtains power from a supply external to the product and maybe not supplied by the manufacturer. I think the questions were related to EFT or surge.

I have a similar situation. Our products are network powered; that is, there is a ferroresonant power supply connected to the network and we just tap into that available power. This is CATV land and not Telco. We do not make the supply nor do we sell them. Our products have switching supplies which run on the quasi-square wave provided by the ferroresonant supply. Voltage of the supply is in the 60-90 VAC range.

Question is: EN 50083-2 : 2001 (4.1.2 Disturbance Voltages From Equipment...) says that if our products fall within the input current range of EN 61000-3-2, then the tests and limits of that standard apply. Then EN 61000-3-2 : 2000 (1. Scope) says that the standard applies to products intended to be connected to public low-voltage distribution systems.

One argument says that we are not connected to the public low-voltage distribution system, instead the ferroresonant supply is. Therefore, since we ARE NOT "connected" we do not need to do the harmonics test. The flip side argument says that we still have to test harmonics because the supply does nothing but provide power to our product and therefore we ARE "connected".

Understand that this "system" consists of power supplies and amplifiers, etc. from one or more than one supplier (read that more than one manufacturer). We cannot guarantee we are the sole provider here, in fact will most likely not be the sole provider. Especially since we do not manufacture or sell power supplies.

So all powerful and wise list, what's a mother to do? Do I, or do I not, test? Am I required to test? Have I missed something?

Thanks for all of the wisdom you are about to impart.

Regards,
Scott Douglas
Senior Compliance Engineer
Narad Networks
515 Groton Road
Westford, MA 01886
phone: 978 589-1869
dougl...@naradnetworks.com
www.naradnetworks.com
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