Both valve actuator motors run against each other

Nov 13, 2015
4
Cathedral City/CA
I have a pair of Pentair PE24VA actuators (24VAC) I just bought and am trying to install. The actuator has three wires: apply 24vac to the red for CW rotation, 24vac to the white for CCW rotation, and the black wire is the "neutral" of the 24vac power for each motor. Each power wire goes to a separate motor (they're stacked on top of each other like hockey pucks). The problem is that when I apply power to either the red OR the white wire, BOTH motors energize fighting each other. Using a voltmeter, I've confirmed that if you apply power to one wire going in, you get 24vac coming back out the other too. I've traced the wiring inside and out and nothing is shorted out and everything checks out OK. Both actuators are acting this same way right out of the box, so I'd be surprised that both of them happen to simultaneously suffer the same malfunction. Anyone ever see this before? What could be wrong?
 
Those motors are wired for opposite rotation and the negative is common to both windings, so if you apply power to one set of windings and check voltage on the other set of windings you will see voltage on it's positive lead. Since there's no power feeding the opposite rotation motor windings, it won't run even though you can read voltage on the + wire.

The only way that the motors could be fighting each other is if the automation device is putting +24 volts on both positive leads at the same time, or it's grounding the unpowered positive lead.

What is controlling the actuators?
 
Thanks for the prompt reply!

The valves are being run from a custom-built home automation system using an ELK M1G as the brains. I've been an automation and controls engineer for 30 years, so I'm fairly sure that end is OK. But what I don't know is the internals of the actuator, so I might be operating under an incorrect assumption about how the actuator itself works.

When I applied power to test rotation, I could hear the motor buzz, but no movement -- regardless of which side was powered, and regardless of the built-in toggle switch (which swaps power to change rotation). When I metered it, I saw I was getting 24vac back out on the unpowered control line.

I see in the manual there's a schematic (attached) that shows a capacitor connected between both control lines. What is that for?
I've been trying to move the actuator by merely applying power to one or the other the control lines. Does the opposing control line also need to be "grounded" at the same time? Right now I've just been letting it float.
Thanks for your assistance.

- - - Updated - - -

Oops, hit "send" too soon, I forgot to answer your question. When I started having trouble, I just hooked the actuator up to a pushbutton, so its just being manually controlled right now for testing purposes.
Thanks.
 

Attachments

  • PentairActuator.pdf
    19.7 KB · Views: 10
OK, I've googled about how split-phase induction motors work (which I should have done first) and understand what the capacitor does, and I seem to be powering it up properly. Which makes my problem even odder, since I can't see any explanation for this behavior. I'm using a conventional 24vac transformer (100VA) for power so there should be enough juice. The motors common is connected to the grounded side of the AC, with the high side connected to the control lines. Its a pretty simple device, there's not much to it.

Is there a gear box under the motor? What RPM does the motor run at compared to the rotation of the valve? I would assume it should only take a few seconds for the valve to rotate.
 
If the motor is buzzing then the limit switches aren't open, so the motor is trying to move.

The unpowered lead should float. The black wire should be hooked to neutral or X2 of the transformer.

Have you checked to make sure you're getting 24vac between hot and neutral of the transformer secondary?
 
Figured out the problem!! The actuator has a feature that lets you disengage the motorized gear train in order to turn the valve manually, by pushing in\pulling out the shaft. I just wasn't pulling it in far enough. The shaft popped in and out about 1/8 of an inch, seeming to hit stops, but it really needed to move about 1/2". The actuators came from the supplier with the shaft disengaged, so out of the box, the motors come on but nothing moves.
I just hadn't been getting the shafts set into the gears properly. It took a little practice since I didn't want to break anything by forcing it, but I finally got the feel for where things needed to fit.
It didn't help that the actuators rotate verrrrrrry slowly. Which makes sense actually -- the actuator motor needs to be highly geared in order to produce enough torque to turn sticky pool valves. I just didn't expect that much of a ratio resulting in THAT slow of movement.
Anyways, everything is working now. Thanks greatly for your assistance, as it helped me work through the problem.
 
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.