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Can I get a relay that reverses polarity for the load when not powered

Steve Bratt

Feb 6, 2017
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I have a linear actuator 12v DC "JS-TGZ-U1" from ebay, im not sure of the amp requirements yet.

The actuator has built in limit switches, and for my purposes "on" will be the actuator open and extended. "off" will be the actuator closed and retracted, no requirement for positioning the actuator other than open and closed.

im tempted to try to use the following Single or double zwave switch controller to activate the actuator.
http://manuals.fibaro.com/content/manuals/en/FGS-2x3/FGS-2x3-EN-T-v1.1.pdf

The way this could work assuming i can use a simple relay is:

12v powersupply (inverter plugged into the mains) to relay. the relay will always supply power to close the actuator when the z wave switch is off. This means if the zwave switch is turned off the actuator will close and then stop at the end of travel using its built in limit switch.

when the z wave switch is on it will power the relay and the relay will invert the power to the actuator, as long as the power is on the relay will always supply inverted power to the actuator, which will open the actuator until it hits its built in limit switch.

the two issues I have are, is there such a relay that can invert the power from a trigger as suggested above, and is there such a relay that could accept 240 volt for the trigger and 12v for the main load? as the fibaro device is 240v UK mains.

Thanks
 

AnalogKid

Jun 10, 2015
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A DPDT relay can be wired to provide one DC polarity when the coil is off and the other polarity when the coil is powered, but power of one polarity or the other is connected to the device at all times. If you want a third state where the device has no DC applied, that is a two-relay solution. Lotsa relays with 240 VAC colis and 12 Vdc-rated contacts.

If you want the relay to latch in its current state when relay coil power is removed, and then flip to the other state the next time the coil is powered, that is called a latching (duh) relay. It is the electromechanical equivalent of a toggle flipflop.

ak
 

duke37

Jan 9, 2011
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Show a circuit diagram of what you want. I think all you need is a change over relay connected the right way round.
You can get relays with 230V AC coils with various sizes of contacts to suit the load.
You should use the 12V supply to energise the relay, then you do not have the danger of high voltages.
 

Steve Bratt

Feb 6, 2017
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unfortunately there doesn't appear to be a 12v zwave switch yet available on the market, so if i want to integrate it into a home automation solution, i need to use on one the mains powered zwave switches. which are for 240V applications, hence the 240 volt requirement. @AnalogKid, there is no requirement for the third state, as the actuator has limit switches, the required polarity can be on permanently as the limit switch will shut it down when it reaches the end of travel. the DPDT relay sounds like the ideal solution, are these expensive?

How do i find out if a relay has a 240v coil and the contacts are 12v rated?

additionally duke, would there be a better way to use the 240v switch power to activate the relay, for instance step it down to 12v first? i assume this is just adding extra bits to the circut that are no safer than just using a 240v relay?

Thanks for the quick replies. Whilst i understand very basic circuits im not sure i know enough to draw a diagram of what i want that wasnt MSpaint blue and red blocky lines. im not sure how helpful that would be
 

duke37

Jan 9, 2011
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The Amazon relay liooks OK but is limited to 5A load. What is the load?
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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Gzzzeeesh, yet another term (Zwave) I had to Google. Technology is passing me by! :(

Chris
 

Steve Bratt

Feb 6, 2017
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The Amazon relay liooks OK but is limited to 5A load. What is the load?

hmm ive not been able to find the amps of the motor, but others ive seen are 10-12 amps so maybe ill go for the bigger one i linked to above. which has a much higher rating, and its not particularly expensive.
 

Steve Bratt

Feb 6, 2017
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hmm i don't know enough about amps, am i correct in thinking that i can safely over provision amps, so if the device is between 3 and 10 amps. using a 12 amp power supply is fine (other than the cost) as long as the voltages match?
 

Steve Bratt

Feb 6, 2017
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finally found the amps

Capture.PNG

according to this 1A at 25kg load and 2A at 75kg load, max i think is 80kg

Technical Reference:
1, permanent magnet DC motor drive; voltage 12,24,36 VDC
2, the maximum push / pull: 80kg / 80kg
3, the standard stroke: S = (50,100,150,600) mm, can be customized
L = S (Stroke) + 105mm Putter fully extended to the distance between the two holes before and after the middle = 2XS (Stroke) +105 mm (stroke) +105 mm), the minimum installation size (putter completely recovered to the distance between the two holes before and after)
5, no-load speed: 10 / s 16 / s 20 / s 25 / s 29 / s
6, the relationship between speed and thrust: 5mm / s (kg) -50s (50kg)
7, the ambient temperature: -26 degrees to +50 degrees
8, the standard protection level: IP54
9, equipped with travel switch
10, the end of the noise design, noise level less than 65dB
11, can be equipped with a cable or remote control.

Can anyone tell me why its listed as 12v 24v and 36v doesnt appear to affect the speed according to those details (translated form Chinese)

Also, ive found a 12v 5A power supply, I assume should be fine?
 
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