Not cheap in my area....you can't buy just the solenoid. You have to buy the whole valve assembly.

You need a better irrigation place.
The solenoid is actually less $ by itself, but they upsell the whole assembly "for just a few $ more". Ez to do when the stuff is cheap stuff. Common practice to move inventory.

If it helps, I have a 24v Irritrol lawn sprinkler solenoid:

Hold current: 220mAC (measured)
Inrush current: 400mAC (spec)
DCR=25 ohms (measured)
L=64mH (uninstalled, measured)
L=77.8mH (installed, measured)

24vac(60Hz)@220mA, the Z has to be 109ohms. Vector sum of R and XL not adding up to 109. L and/or Rdc is not correct?

 

You need a better irrigation place.
The solenoid is actually less $ by itself, but they upsell the whole assembly "for just a few $ more". Ez to do when the stuff is cheap stuff. Common practice to move inventory.

About $35 USD each assembly. I have six. :-|

24vac(60Hz)@220mA, the Z has to be 109ohms. Vector sum of R and XL not adding up to 109. L and/or Rdc is not correct?

The L and R(DCR) are correct. Those are measured values.
220ma might be a little off as I don't remember the exact measurement value, but it is definitely between 200-220ma. Spec says 200mA. If I get some time later today I'll measure again.

 

The L and R(DCR) are correct. Those are measured values.
220ma might be a little off as I don't remember the exact measurement value, but it is definitely between 200-220ma. Spec says 200mA. If I get some time later today I'll measure again.

64mH @ 60Hz = 24.1 XL
Rdc = 25
sqrt(25^2+24.1^2) = 49.1 ohms(Z)
24/49.1 = 488mA

So, I run the math, it does not agree with electromagnetism and ohms law equations. Need to reconcile.

 

64mH @ 60Hz = 24.1 XL
Rdc = 25
sqrt(25^2+24.1^2) = 49.1 ohms(Z)
24/49.1 = 488mA

So, I run the math, it does not agree with electromagnetism and ohms law equations. Need to reconcile.

Ok...I've re-measured the solenoid:

Vin=24.0VAC
I=230mA
RDC=26 ohms
L=96.0 mh (in)
L=63.3 mh (out)

But using L=96mh the math says:
Z=36.191+26=62.191
Irms=538.572mA
Ipk=761.54mA

The driver would need to deliver at least Ipk +drate 50%.
So, If I believe the math, the driver needs to deliver at least ~1.1A per solenoid.
but, actual measurements say, the driver needs to deliver at least ~848mA.
Either way, 1.1A driver would work.

Not sure about the differences in the numbers. Maybe my LCR meter is not really measuring at 60Hz.

 

What is Lin vs Lout?
Z is not math addition of "+", it's a vector sum of XL XC and Rdc.
Z=sqrt(Rdc^2 + (|XL-XC|)^2))

An LCR meter typically uses 1kHz to measure, but then you run the math using that L and 60Hz.

96mH and 26Rdc @ 60Hz = 44.56 Z ohms

24/44.56 = 538mA

 

In many solenoids the inductance changes quite a bit as they move together inside. I learned about that when we were developing a test for valves in an electronic controlled automatic transmission quite a while ago. That is why on many AC solenoid devices the holding current is usually a lot less.. So both numbers are probably correct, because the current will drop when the valve operates.

 

AC contactors (which are much the same thing, mechanically) complete the magnetic circuit when they operate, so when power is first applied to the coil, there is a gap in the magnetic circuit, the inductance is lower, more current flows.
The magnetic circuit is completed when the solenoid operates, increasing the inductance, which reduces the current to a value which will hold the solenoid in the “operate” position, and saves power.

 

Holding amps usually has to do with the mechanics. Once a arm moves it can be held with less amps.

In a solenoid, as long as the "slug" makes XL go up when activated, then the amps will go down.

Back to the question at hand. An SSR with fuse should suffice.

 

Holding amps usually has to do with the mechanics. Once a arm moves it can be held with less amps.

In a solenoid, as long as the "slug" makes XL go up when activated, then the amps will go down.

Back to the question at hand. An SSR with fuse should suffice.

"Holding amps" drop because the magnetic path becomes closed and that in turn increases the inductance, which increases the impedance which reduces the current.

 

How do I troubleshoot why I have such a large voltage drop with my triac setup? A coworker had someone measure a triac output of a similar device, had 26.5VAC going in, and 25.5VAC going out of the triac to a solenoid. I have a much larger voltage drop and is yielding closer to 19-20VAC out of the triac. Did I configure something incorrect with the triac or supporting components?

Here is the circuit again for reference. In my case, "24VAC_RED" is 24-25VAC comming directly from the transformer. "24VAC_COMMON" is the common also comming directly from the transformer. "24VAC_OUTPUT1" is the output from the triac, and is where I am seeing the large voltage drop, e.g. getting only 19-20VAC.

 

Are you using a random phase triac instead of a zero crossing type maybe?

 

Are you using a random phase triac instead of a zero crossing type maybe?

The MOC3063 handles the zero crossing.
http://isocom.com/wp-content/uploads/2018/03/dd93230-moc306x-050318.pdf

 

How do I troubleshoot why I have such a large voltage drop with my triac setup? A coworker had someone measure a triac output of a similar device, had 26.5VAC going in, and 25.5VAC going out of the triac to a solenoid. I have a much larger voltage drop and is yielding closer to 19-20VAC out of the triac. Did I configure something incorrect with the triac or supporting components?

Here is the circuit again for reference. In my case, "24VAC_RED" is 24-25VAC comming directly from the transformer. "24VAC_COMMON" is the common also comming directly from the transformer. "24VAC_OUTPUT1" is the output from the triac, and is where I am seeing the large voltage drop, e.g. getting only 19-20VAC.

View attachment 258370

Measure the voltage drop across the PTC

 

53 posts and I haven't seen any measurement of the actual transformer output voltage when connected directly to a solenoid.

 

I already explained earlier that this does not work because I cannot protect the SSR from over current scenarios

Have you looked at a CPC1988J?
https://www.ixysic.com/home/pdfs.nsf/www/CPC1998J.pdf/$file/CPC1998J.pdf
Less complicated circuit.

 

As has been stated previously, to locate the source of the voltage drop, measure the voltage across each component in the circuit while current is flowing. Start with measuring the voltage across the supply transformer, Then measure the voltage across the triac terminals. Then measure the voltage across that PTC protection device. Then finally measure the voltage across the solenoid valve terminals, first at the contoller board and then at the valve. The sum of the voltage drops should be the same as the supply voltage , otherwise some drop is hidden where you did not look. When no problem is obvious that is how we find the problem. Twice it has been a high resistance test lead. Other times a loose terminal screw.

One more question: How well does the solenoid valve work with only 19 volts?? My guess is that it operates very well.

 

How do I troubleshoot why I have such a large voltage drop with my triac setup? A coworker had someone measure a triac output of a similar device, had 26.5VAC going in, and 25.5VAC going out of the triac to a solenoid. I have a much larger voltage drop and is yielding closer to 19-20VAC out of the triac. Did I configure something incorrect with the triac or supporting components?

Here is the circuit again for reference. In my case, "24VAC_RED" is 24-25VAC comming directly from the transformer. "24VAC_COMMON" is the common also comming directly from the transformer. "24VAC_OUTPUT1" is the output from the triac, and is where I am seeing the large voltage drop, e.g. getting only 19-20VAC.

View attachment 258370

Why is the Triac (T1) gate being driven by AC? Ditch R1, connect R5 from OK1 pin4 to gnd, connect OK1 pin 6 to +5v, swap the 3063 for a std opto-fet (pinout is same as OK1), feed pin 6 with +5v. Leave rest as-is.

R18 and R19 are 100k? Why? You want crisp pulldown and crisp turn-on, and less noise, R19 10k, R18 1k. The microcontroller should be able to source Q1 gate charge without any issue, pulldown will sink it.

At this point, to really see what's going on in that overly-complicated ckt, need to look at in on a scope. I suspect there's more going on than what you are seeing on any volt meter.

I see this as a four parts solution. SSR, PTC, LED, Resistor. 1sec, make schematic.

 

Let's start with just the power side. S1 can be whatever you like, an opto, a fet SSR, whatever. fet SSR uses less power.
R1 is of course connected to LED (me running too fast).
LED will still light up on AC, etc.
L1 is your solenoid.

 

Are you inable to measure the voltage drop acros the different parts, as two of us have suggested? That is the way to discover where the problem is. So far a number of folks have gone into panic because of no surge suppression, when surge is not part of the question. Unless the transformer voltage drops under load, it is either the triac or the overcurrent protection device causing the drop, or a poor connection.
So the voltage drops will show exactly where the problem is.
Otherwise there is just a bunch of guesses, some better than others, but all just guesses. And you did ask how to troubleshoot and you did get correct answers from at least two sources, so what more???

 

If there are any weird oscillations going on, then using a standard volt meter is not gonna be good enough.

That 8g triac also appears to turn on around 1.3v (Vgt), which needs to sink Igt (20mA) before the thing even turns on, but the ckt has a voltage divider on the gate, hence the AC needs to be above 1.3v by a factor of the divider ratio, hence the divider makes the dead zone even bigger. If you scope the voltage on the solenoid I bet ya it's not a pretty sine wave. Then with the weird on/off characteristics I bet ya the solenoid inductor is making things look funky when probing with std volt meter.

Triacs have their place, but I think for this application you use fet SSR for S1 in post #58. Simple, no weird on/off characteristics, no periods of open ckt (when on), etc etc. 11 parts down to 4, maybe 6 if you use two resistors for MC to SSR gate (current limiter and a pull down).

Post #58 does have a "look-out" in there. The EMF from off'ing the inductor means need to be careful with that LED, but in general it should be ok. Noted, EMF all depends on where the mag field is at when the thing goes sudden off, it's AC, etc.

Post #55 is a nice part, but original schematic suggests the MC 3.3v is high impedance cmos level. If the MC can source the mA needed for the two light diodes, then good, otherwise need that n-fet and +V to drive the driver and LED.