[Amps] time to death in the event of a blower failure

Jeff Blaine keepwalking188 at yahoo.com
Sun Nov 7 20:27:36 PST 2010


The traditional monitor for a failed blower is a air pressure sensor.  But this is harder to implement with a variable speed fan arrangement.

I was working on a fail-safe for this case and thought a solution.  Wanted to run that idea by the board to see what the comments are...

Here’s the idea...

1. The cut-out mechanism would be one of these TO220 sized bimetal switches.  They are available in a variety of trip points.  

2. The switch has no electronics inside and should be RF immune.  

3. The switch can be set in the chimney near the silicon wall and would not significantly impede airflow.

4. The switch has a very low thermal mass and will switch quickly.

5. Even with a failed blower, the tube would be dissipating tons of heat and convection would ensure heat-up of the switch.

73, Jeff ACØC
www.ac0c.com


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