DIYbanter - View Single Post - Help needed. Zero crossing with RC snubber problem

legg

On Fri, 29 Feb 2008 11:36:51 -0500, Fred Bloggs
wrote:

legg wrote:
On Fri, 29 Feb 2008 03:43:59 -0500, Fred Bloggs
wrote:

I'm aware of that. Generally AC coils with predominantly reactive
impedance are rated in VA and the so-called impedance limited coils with
impedance dominated by coil wire resistance are rated in Watts. The OP
is working with a 6W impedance limited coil.

Sorry, but I don't see a resistance limited coil described in any
correspondence from the OP.

The most common ( old P&B now Tyco ) contactor for high current that
still offers AC coils and a fair description of their impedance and
wattage expectations:

http://tinyurl.com/3845jx

RL

That link proves my point, the AC coils are specified in Volt-Amps and
the listed DC resistance of those coils is ~20% of the reactance. The
fact that the OP describes his coil as AC and 6W means it's impedance
limited.

Could you post a link to a data sheet for any device meeting this
description? I am unable to find a relay in this coil power range that
even has an AC-operated rating specified in W, never mind one
operating at this power level resistively.

I see some smaller ones that come close to 45 degrees, but are still
on the inductive side. I guess it's hard to avoid, being a magnetic
component.

I appreciate that there's some confusion here, but I have a suspicion
that it is most likely to originate with poor characterization by the
OP. I see no reason to carve the misunderstanding into electronic
stone on the news server.

RL

Here is one that does MUCH MUCH better in my original snubber circuit
that you, in your infinite wisdumb, cut.
http://www.components.omron.com/components/web/PDFLIB.nsf/0/109B19860C4214F385257201007DD570/$file/G2R_0607.pdf

This is a 400mw/0.9VA relay coil.

RL