Post by Deleted on Mar 25, 2014 23:58:54 GMT -5
So most 3 and 4 speed wall controls have a current rating of 1-1.5 amps, i.e. one fan only.
But they consist only of a 4 way switch, capacitors, and in some cases, resistors to discharge the capacitors.
Capacitors have no current ratings. A capacitor is by definition a current limiting device, so it's impossible to hook something to it that draws too much current.
Therefore, there should technically be no maximum current rating for capacitor based switches. Or, it should be the current rating of the 4 way contactor, which is usually something like 6a 125v.
And yet, on two separate occasions now, I have connected two stack motor fans to the same capacitor based switch, got satisfactory speeds, and yet the control has gone up in smoke when left on either medium low or medium high.
I have measured the voltage drop across the control in cases where it has burned up, and cases where it hasnt. In all cases it's around 135vAC.
I have measured the current draw of the pair of fans that toasted a control most recently. On high, 1.8a. On medium high, the offending speed: .9a.
It's been suggested that there is a sweet spot between a capacitor and an inductor that, when both values form a "sweet spot", it creates a very high voltage drop and therefore current draw (think tuning in a radio) but that doesnt seem to be happening here.
Further data:
Two Nutone Verandah Deluxes on the same control have toasted the control (on speed 3, speeds 4 and 2 were fine).
Two Emerson Casablanca Classics (small K55 newer version) on the same control have toasted the control (on speed 2, speeds 4 and 3 were fine).
Three 36" Designers on the same control have NOT toasted the control.
Two Moss Caribbean Breezes and one Encon CG on the same control have NOT toasted the control.
Two Envirofan Gold Lines on the same control have NOT toasted the control.
Two Casablanca Four Seasonses on the same control have NOT toasted the control.
A Key Largo? GE stack motor and a Casablanca Broadway on the same control have NOT toasted the control.
A Key Largo? GE stack motor and a Casablanca Four Seasons on the same control have NOT toasted the control.
An Emerson Casablanca Classic (large K55 older version) and a Lasko top mount on the same control have NOT toasted the control.
These controls have an 8uf capacitor for low, a 12uf for medium low, and they are paralleled for medium high.
In both cases, it has been the 12uf capacitor and the resistor across it that have failed.
Anyone?
But they consist only of a 4 way switch, capacitors, and in some cases, resistors to discharge the capacitors.
Capacitors have no current ratings. A capacitor is by definition a current limiting device, so it's impossible to hook something to it that draws too much current.
Therefore, there should technically be no maximum current rating for capacitor based switches. Or, it should be the current rating of the 4 way contactor, which is usually something like 6a 125v.
And yet, on two separate occasions now, I have connected two stack motor fans to the same capacitor based switch, got satisfactory speeds, and yet the control has gone up in smoke when left on either medium low or medium high.
I have measured the voltage drop across the control in cases where it has burned up, and cases where it hasnt. In all cases it's around 135vAC.
I have measured the current draw of the pair of fans that toasted a control most recently. On high, 1.8a. On medium high, the offending speed: .9a.
It's been suggested that there is a sweet spot between a capacitor and an inductor that, when both values form a "sweet spot", it creates a very high voltage drop and therefore current draw (think tuning in a radio) but that doesnt seem to be happening here.
Further data:
Two Nutone Verandah Deluxes on the same control have toasted the control (on speed 3, speeds 4 and 2 were fine).
Two Emerson Casablanca Classics (small K55 newer version) on the same control have toasted the control (on speed 2, speeds 4 and 3 were fine).
Three 36" Designers on the same control have NOT toasted the control.
Two Moss Caribbean Breezes and one Encon CG on the same control have NOT toasted the control.
Two Envirofan Gold Lines on the same control have NOT toasted the control.
Two Casablanca Four Seasonses on the same control have NOT toasted the control.
A Key Largo? GE stack motor and a Casablanca Broadway on the same control have NOT toasted the control.
A Key Largo? GE stack motor and a Casablanca Four Seasons on the same control have NOT toasted the control.
An Emerson Casablanca Classic (large K55 older version) and a Lasko top mount on the same control have NOT toasted the control.
These controls have an 8uf capacitor for low, a 12uf for medium low, and they are paralleled for medium high.
In both cases, it has been the 12uf capacitor and the resistor across it that have failed.
Anyone?
