How much is too much ssr current leak?

[lupulinaddict]

I built a bcs panel using ebrewsupply's book. Im about ready to actually plug in elements and pumps to do a water walk through test, but was wondering about the pump ssr's current leakage. There is lot of threads that a little leaking is normal, usually element LEDs, but when should you be concerned? I have three ssr's each controlling a pump, and they vary from 8-11volts. It seems like that would be bad for the pump? It's probably not enough to turn on the pump, but would it wear down the motor because it's underpowered? it seems like that low voltage measurement is never the same. Sometimes it's 3v, sometimes 8volts. I just replaced one of the ssr's because when I measured it, it was at 108volts off. That one I figured would turn on the pump, and that was most likely defective, so I swapped it with a new one and now it's in the 8-11v range. Does the ssr fail at one time, or does it gradually get worse? Should I periodically check the off voltage to make sure it doesn't increase overtime to like 20v, 30v, or more volts? If so, when is too much to power to be harmful to the pump?

 

[doug293cz]

Measure the resistance of the motor's winding (unplug the pump, and measure across the power tabs on the plug.) The leakage current can then be determined from Ohm's Law: V = IR or I = V/R. Using the measured "off" voltage across the pump, the calculated I should be less than 0.005 (5 mA), based on several SSR spec sheets.

Brew on

 

[lupulinaddict]

Measure the resistance of the motor's winding (unplug the pump, and measure across the power tabs on the plug.) The leakage current can then be determined from Ohm's Law: V = IR or I = V/R. Using the measured "off" voltage across the pump, the calculated I should be less than 0.005 (5 mA), based on several SSR spec sheets.

Brew on

Thanks for the help doug239cz. I'm not sure what I'm doing is right. I set my multimeter on the 200 ohm setting and put the probes on the two spades of my pump's plug. I got a reading of about 9.3 (it jumped around a bit but stayed around 9). If I divide my voltage at the pump's receptacle when the panel switch for the pump is off (8volts-11volts) it's going to be around one.

I tried researching ohms law tonight, because I haven't seen it since high school, trying to figure out why it was important from your post. So I am sort of confused and my brain is numb, but this is where I'm at tonight, please correct me if i'm wrong. I think from what your telling me I have 8-11v at my receptacle, but regardless, should only have 5mA of current. Why that's relevant is because the volts are only "potential" energy, but the amount of current is so low there isn't enough "flow of energy" traveling through the ssr to the pump to do anything with the 8-11v? Does that sound like I'm on the right track?

 

[doug293cz]

Thanks for the help doug239cz. I'm not sure what I'm doing is right. I set my multimeter on the 200 ohm setting and put the probes on the two spades of my pump's plug. I got a reading of about 9.3 (it jumped around a bit but stayed around 9). If I divide my voltage at the pump's receptacle when the panel switch for the pump is off (8volts-11volts) it's going to be around one.

I tried researching ohms law tonight, because I haven't seen it since high school, trying to figure out why it was important from your post. So I am sort of confused and my brain is numb, but this is where I'm at tonight, please correct me if i'm wrong. I think from what your telling me I have 8-11v at my receptacle, but regardless, should only have 5mA of current. Why that's relevant is because the volts are only "potential" energy, but the amount of current is so low there isn't enough "flow of energy" traveling through the ssr to the pump to do anything with the 8-11v? Does that sound like I'm on the right track?

Yes, you're on the right track.

The DC resistance of the motor winding might not be a good number to use. The winding is obviously highly inductive, so its AC impedance might be quite a bit higher, which would cause higher voltage readings at lower currents.

Brew on

 

[augiedoggy]

What kind of ssr's are these? The only ones Ive used with real noticable current leakage was the cheapy fotek knockoffs? You might be better off with the $8 mager ones which are much better quality instead of the $4 fotek ssr's.

If you are using the cheap white ebrew supply ssrs I'm 99% sure they are nothing more than rebranded foteks so they would likely have the same design weakness... I know the $42 dollar heating elements they sell are actually super cheap units made and sold for as little as $3 a piece when ordered from the manufacturer here http://www.alibaba.com/product-deta...62175659.html?spm=a2700.7724838.30.260.wVmlxj in bulk so I wouldnt put much faith in the ssrs being anything special as far as quality.

If you do have the ebrew ssr, I bet if you pop the coverplate or remove the sticker you will find the led hidden under than circle on the sticker they decided to not knock out to give the ssr a different appearance from its $3 counterparts. Then again it could be the real Fotek and not one of the clones. being that they now offer what looks like the mager made ssrs as a "Version 2" ssr Makes one wonder if they have had quality issues with the white ones.