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  #31  
Old 05-25-2013, 08:28 AM
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Wet_Boots Wet_Boots is offline
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Originally Posted by 1idejim View Post
The W*M plastic thread measures 35 ohms and the brass thread measures 30 ohms right out of the box Shoes.

I might be doing something way wrong but i don't change out solenoids unless they measure short (below 10) or open (OL or 1)
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I change out solenoids when they trip the overload circuitry. If I ever did get into preventative solenoid replacements, it would be based upon operating current measurements, and not resistance.
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  #32  
Old 05-25-2013, 11:37 AM
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If I ever did get into preventative solenoid replacements, it would be based upon operating current measurements, and not resistance.
What the big guy said.
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  #33  
Old 05-25-2013, 05:07 PM
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1idejim 1idejim is offline
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Well fellas, explain this to me.

If your I=0.2 , what are your E & R values?
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  #34  
Old 05-25-2013, 07:29 PM
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Originally Posted by 1idejim View Post
Well fellas, explain this to me.

If your I=0.2 , what are your E & R values?
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the trouble with I = E/R, is that the 'R' you got with an ohmmeter measurement is not the actual "Reactance" at 60 Hz (Reactance is term that works in AC circuits, where current and voltage are not in phase with each other)
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  #35  
Old 05-25-2013, 08:50 PM
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Originally Posted by Wet_Boots View Post
the trouble with I = E/R, is that the 'R' you got with an ohmmeter measurement is not the actual "Reactance" at 60 Hz (Reactance is term that works in AC circuits, where current and voltage are not in phase with each other)
answer the question
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  #36  
Old 05-26-2013, 03:59 AM
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answer the question
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They are vector quantities, with a phase angle. We all know that any solenoid resistance we measure with an ohmmeter is going to be only a small portion of the actual operating impedance, due to the inductance of the solenoid coil and its magnetic core.

If a solenoid draws 0.2 amps with 24 volts applied, it shows an impedance of 120 ohms.
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  #37  
Old 05-26-2013, 02:15 PM
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Originally Posted by Wet_Boots View Post

If a solenoid draws 0.2 amps with 24 volts applied, it shows an impedance of 120 ohms.
No matter how i respond to your post it sounds like i am attacking you when i'm not.

The answer to my question is "you can't know E or R without measuring them."

You can shift focus by introducing phase angle, impedance and reactance and quoting Wikki or ABC or my main reference guide UGLY'S but my question was what are E and R? Without measuring them you don't know, you assume.

When high or low current is at fault in a system, one can choose a path to troubleshoot by measuring I-E-R.

High I should be blowing fuses and either R will measure low or Line/transformer output will measure extremely high.

If the I is low or non-existent then the R will be very high, up to and including infinity.

You can't have your cake and eat it too, an electrical circuit has to have E and R to produce useable I and these have to each be in porportion to each other.

Your journey into Z (impedance) and X (reactance) as well as phasing (measured L-1 to ground and L-2 to ground) may be above the pay grade of most of this crowd (i'm no electrical engineer) but bottom line, not the answer.

Solenoids are manufactured to specific resistance ranges to reduce current loads, and have been so since the 70s.

The standard 20-60 ohms still works for the most part when diagnosing a solenoid and wire path.

Below 8 still means there is a short somewhere and 180 still gives heed to poor splicing.

When i see high amps and blown fuses i look at the resistance of the solenoid and the wire path along with the line and transformer output.

Beats hell outta putting in higher amperage fuses.

No harm, no foul
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  #38  
Old 05-26-2013, 02:19 PM
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cyclops speak with forked tongue

here's a vector diagram of what goes on with solenoids - note that the resistance is only a small part of the actual operating impedance
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  #39  
Old 05-26-2013, 03:34 PM
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Originally Posted by Wet_Boots View Post
cyclops speak with forked tongue

here's a vector diagram of what goes on with solenoids - note that the resistance is only a small part of the actual operating impedance
This only is about Z in your mind Shoes. My point is that without measuring E, I and R you are guessing and troubleshooting via replacement.

I made my point and that's what matters.


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  #40  
Old 05-26-2013, 04:03 PM
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The math, as displayed in the vector diagram, makes it clear that measured solenoid resistance is not so very material to actual performance in a system, since the inductive reactance in the scenario you supplied allows for operation without overload, even if you had measured zero ohms solenoid resistance.

(of course, dead-shorted solenoids aren't going to generate the magnetic field that is responsible for inductive reactance, but a below-spec solenoid resistance, in combination with the usual amount of inductive reactance, would not prevent zone operation)
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