Looks like a plastic capacitor that has tried to get rid of its encapsulation.

Try to show more of the actual component and less of that barn door.

 

Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

Some sort of metalised film capacitor: value is 2.2uF, 10%, 250V. What duty is it used for? That might give a clue what dielectric was used, or at least what you could use as a replacement.
  

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If we learn from our mistakes I'm getting a great education!
 

The component is used to "short" across a switch.  When the switch is on full power is sent to a device such as a fan.  When the switch is off this component allows a reduced level of power to get to the device.  In the case of a fan it runs at a slow speed when the switch is off and at full speed when on.

Not being familiar with this component I was wondering if it is suitable for long term use in this arrangement.  The power lines are 115 and 230 VAC.  The picture shows the component after it was removed from encapsulation, thus the damage.  It is not a failed component.

Speaking of failures - from my described application and your comments regarding the type of component what would be the likely mode of failure?  Would the component fail open or closed (or something else)?  Would there be a danger in this failure?  Could I expect a life of 5-10 years of continuous use?

These forums are great!  I appreciate all your constructive input.

- - -Updraft

Most likely a cheap polyester capacitor.  Since you are passing current through it, the specification sheet should say "AC rated capacitor".  Many capacitors are not rated for current because they can easily have 10 ohms of internal resistance. Correct capacitor would hav less than half ohm. I wouldn't use that capacitor at 220VAC.  People can get away with it for a while, but it will eventually fail.

Mains rated capacitors are marked Class X or X2 where a failure can not cause a fault to earth, or Class Y where a failure would cause a fault to earth. For this application a Class X or X2 type would be appropriate.
  

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If we learn from our mistakes I'm getting a great education!
 

The part is a Panasonic metallized polyester film capacitor (the "M" symbol is Panasonic). Probably of the ECQE family.

http://www.panasonic.com/industrial/components/pdf/abd0000ce23.pdf  Although this data sheet is black-n-white, the actual capacitor case color is a dull red like yours.

The part you show is 2.2uF at 250 Volts (DC). These are frequently used on AC filter circuits (outputs of pure sine-wave inverters) and snubbers where there's a lot of ripple (low dielectric absorption give good low-loss) and some self-healing properties (of metalized polyester) may be needed.

If it is across a switch, I am guessing that the switch is controlling an inductive load. In which case, it is intended to absorb the turn-off transient and spare the switch contacts from arcing.

Seem excessive for that purpose.  How about just a speed switch.  Capacitor in low, out high.

Keith Cress
kcress - http://www.flaminsystems.com

2.2 uF is definitely too much for a snubber protecting a switch at around 200 V. Also, if you use such a large capacitor, you need a resistor to prevent the switch from being destroyed by discharging the capacirot when closing. Is there a resistor in series with the cap?

OTOH, it can be a parallel snubber across a load and the voltage may be a lot lower. Still, 2.2 uF is much for a snubber. Resistor usually still needed.

Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

Keith / Gunnar,

From the earlier description I had pictured the cap being in series with the motor winding and bypassed by the switch, i.e. shorted out, when high speed was selected. Crude and tough on the capacitor.
  

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If we learn from our mistakes I'm getting a great education!
 

Quote:

The component is used to "short" across a switch.  When the switch is on full power is sent to a device such as a fan.  When the switch is off this component allows a reduced level of power to get to the device.  In the case of a fan it runs at a slow speed when the switch is off and at full speed when on.

I agree!

Keith Cress
kcress - http://www.flaminsystems.com

Thanks everyone for the help thusfar.  Comcokid has correctly identified the component and even provided a link to the dat sheet.  A star for you!

Knowing this information perhaps I can better explain the application and get the group's feedback.  The cap is wired in parallel across a conventional wall switch currently wired to 115 VAC.  The load is a small AC motor (single phase, ~35W) that runs with full power when the switch is on, thereby "ignoring" the cap.  When the switch is off the motor still operates, though at a lower speed due to the reduced input coming through the capacitor.  I say reduced input because I don't know what the motor is seeing from the capacitor.  I suspect that since the cap is on an AC line the voltage is somewhat "chopped" and it must certainly be something other than a sinusoid (I am not a EE so please be kind).

The purpose of the component is to allow the motor to run at a slower speed when the switch is off.

My general question is this - what concerns/comments can you share regarding this arrangement?

My specific questions are:
1. What can I expect in the way of life of this component?  It will be continuously feeding power for as long as the house has power.
2. What would be the typical modes of failure and what would be their consequences?  (Fail-open, Fail-closed, Fail-FIRE!, Fail-rupture?)

Several of you have made comments regarding snubbers, absorbing transients, hard on the cap, etc.  Knowing my application and concerns what do those perspectives say about this application?

I very much appreciate all your comments.  Please keep it up!

- - -Updraft

Yes, Scotty. That seems more plausible.

Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

If you try to modify speed by changing the value there could be a big problem!  I bought a number of nice muffin fans years ago, but they were 220V.  I put a capacitor in series with them on 120V to BOOST the voltage on the motor.  If I remember, about 3uF raised the voltage on the fan to 180V which makes it run real quiet.  The series capacitor and inductance of the motor form a tuned circuit.  Off frequency each acts as a resistance to current, but near resonance the current and voltage across each increases to higher than the supply.  Just be aware of this.

The failures would be short or open.  These capacitors are self healing from line spikes, but that also makes them likely to open.  The welds of the wire to the foil are the weakest part.  

Looks like a bomb