powering an actuator

I have an actuator (motor controlled tap) which I’d like to use to control (essentially open or close) one of the two water jets on my micro hydro turbine.

The actuator has a common and two power wires, one to open the tap and the other to close. Once either fully open or fully closed the motor automatically shuts off.

So I need to control the opening and closing of this 12v actuator from an Uno. I have a 48v battery bank on the micro hydro and have a 30-60v input buck converter to run off these batteries which drops voltage to 12v, so this will be the power for the actuator.

So I’m guessing I need a relay (or two?) to control the two power wires (forward/reverse) on the motor. I know how to connect up the arduino side of the relay and signal it, but I’m wondering on the correct wiring for the relay output side. Do I need two relays (one for each motor direction) or can I use NO and NC to control the motor direction?

Also, when a relay is activated but no power is drawn at the output (ie when the actuator tap is fully open or fully closed and the motor then shuts off independently of the relay)) does the coil in the relay still consume power until it is signalled off?

TIA 8)

Use one relay for direction, and another relay for on/off.

Connect 12volt to the common (CO) contact of the on/off relay, and the normally open (NO) contact to the CO of the direction relay. The NO and NC contacts of the direction relay go to the motor direction wires.

Activate the on/off relay for one direction.
Activate the direction relay, wait/delay 50ms, then activate the on/off relay for the other direction.

nzmuzzer:
...does the coil in the relay still consume power until it is signalled off?

You ofcourse add code that turns the relays off after some time.
You can even sleep the Arduino, so almost no power is used.

You also might have to use a snubber circuit across the motor if the Arduino randomly resets.
Leo..

No it appears it will maintain its position. Not sure what you are trying to do but two relays will work. Connect the relays is such a manner NC (Normally Closed) feeds the NO (Normally Open) to the other. This will prevent you from activating both directions at the same time if something goes wrong with the controls. Another way if to use push buttons where; Button 1 NO is fed from the NC of Button 2; then Button 2 is fed from the NC of Button 1. What happens is when one of the buttons is pressed it disables the second. If both are pushed nothing happens. I hope this helps.
Good Luck, Have Fun!
Gil

Hi,

The actuator has a common and two power wires, one to open the tap and the other to close. Once either fully open or fully closed the motor automatically shuts off.

As the actuator has built in limit switches to stop the motor , you only need a direction relay.
Relay activated actuator turns one direction.
Relay de-activated actuator turns the other direction.

Tom.. :slight_smile:

RotaryActuator.jpg

Not sure if OP wants it fully open or fully closed Tom.
If you need it partially open/close, then you need that second power relay.
Leo…

Thanks all for the expertise. I don't need partially opened or closed so I'll have a go using the single relay thanks TomGeorge. All the answers are great and I'm thankful to you all for that, my understanding of relay operation is much increased.

To clarify, the idea behind this control of my micro-hydro for heating; I have a two jet micro-hydro. Each jet provides water for about 500w of power generation when activated. Normally one jet is easily sufficient for my needs but when there is little sun and my solar water heater is struggling to heat our water the power element in the hot water cylinder kicks into action. This 1000w element currently takes power from the batteries only when they are near full (to prevent battery damage from over-cycling). This is Arduino controlled. When this element is activated I want to be able to automatically open the second jet for extra power generation, but close it when not needed to lower noise, water usage and unnecessary wear on the turbine.

Out of interest, I see there are "motor controllers" available for Arduino. Are there any advantages/disadvantages to using these over a simple relay(s) setup?