Geo-TH,In
Well-known Member
The question of how do I test a capacitor has been asked many times here and there are many good responses.
I don't recall anyone posting using an amprobe to test caps. So I calculated the capacitive reactance of a 10 mfd using 60 hz. Then divided 120vac by Xc. Came up with 0.452 amps. So for every 10 mfd a good cap will use 0.452
. Some may question the work use, so lets say, 0.452 amps will pass through the cap. I then connected a 23, 35 and 190-220 mfd cap to 120 vac.(the start cap has a range of 190 to 220 mfd stamped on it. My test shows it appears to be close to 200). Within the accurary of the caps and meter, I was surpised how close the currents were to the calculated values.
The 23 and 35 cap, run caps, also passed the spark test. The 190-220 is a start cap, electrolytic cap. If I recall, could be wrong and I sure someone will tell me I'm wrong either way, electrolytic caps are by designed are leaky and should only be used for a few seconds at a time during start. If anyone questions this, please leave one plugged in while filming it. Wait for it to blow.
As for me, I use amprobe while cap is on motor and look for current. If I have current, good chance cap is good. No current and voltage is applied to cap, good chance cap is bad. I will simply replace cap. Have buckets full us used ones.
Been playing with electrical devices for 45 years. Never saw a need to buy a cap tester. Substition works best for me. Amprobe also tells me if start cap is being removed after motor starts.
Please try using an amprobe method before you tell me it won't work.
I don't recall anyone posting using an amprobe to test caps. So I calculated the capacitive reactance of a 10 mfd using 60 hz. Then divided 120vac by Xc. Came up with 0.452 amps. So for every 10 mfd a good cap will use 0.452
. Some may question the work use, so lets say, 0.452 amps will pass through the cap. I then connected a 23, 35 and 190-220 mfd cap to 120 vac.(the start cap has a range of 190 to 220 mfd stamped on it. My test shows it appears to be close to 200). Within the accurary of the caps and meter, I was surpised how close the currents were to the calculated values.
The 23 and 35 cap, run caps, also passed the spark test. The 190-220 is a start cap, electrolytic cap. If I recall, could be wrong and I sure someone will tell me I'm wrong either way, electrolytic caps are by designed are leaky and should only be used for a few seconds at a time during start. If anyone questions this, please leave one plugged in while filming it. Wait for it to blow.
As for me, I use amprobe while cap is on motor and look for current. If I have current, good chance cap is good. No current and voltage is applied to cap, good chance cap is bad. I will simply replace cap. Have buckets full us used ones.
Been playing with electrical devices for 45 years. Never saw a need to buy a cap tester. Substition works best for me. Amprobe also tells me if start cap is being removed after motor starts.
Please try using an amprobe method before you tell me it won't work.