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Thread: Solid State Relay or Solid State Switch

  1. #1

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    Thumbs up Solid State Relay or Solid State Switch

    Why use a relay instead of a switch?


    The Central point is accommodation, well-being, and cost. Transfers are littler and more affordable than switches. With a switch, you'll additionally need to run thicker wires (enough to deal with 30 - 40 amps) since it requires more voltage than a transfer. Think about a hand-off as a remote, it gives security by giving you additional separation from the power supply.


    The wires of an SSR are littler and of a higher gage than a switch. SSRs are likewise speedier, little and have a more extended lifetime than a mechanical relay. They help increment security since you're managing a lesser voltage and amperage, giving you a littler voltage/amperage controlling a higher voltage/amperage. According to the datasheet of MCTC4825JLB https://www.icrfq.com/part/3155335-MCTC4825JLB.html for substantially higher voltages an SSR is an incredible option when a general switch can't be utilized on account of wear out under the current.


    Solid State Relay (DC/DC):


    Interface (R) positive terminal to the push catch switch.
    Interface (R) negative terminal to the negative terminal on battery 1.
    Interface (L) positive terminal to the positive terminal on battery 2.
    Associate (L) negative terminal to the positive terminal on stack.


    Battery 1:
    Note that battery one was utilized as separation.
    Associate the negative terminal of battery 1 to the negative terminal of the SSR (R).
    Associate the positive terminal of battery 1 to the push catch switch.


    Push Button Switch:
    Interface one terminal to the positive terminal (R) of the SSR.
    Associate the second terminal to the positive terminal of battery 1.


    Load:
    Interface the positive terminal of the heap to the negative terminal (L) of the SSR.
    Associate the negative terminal of the heap to the negative terminal of battery 2.


    Battery 2:
    Associate the positive terminal on battery 2 to the positive terminal on the yield.
    Associate the negative terminal on battery 2 to the negative terminal on the heap.


    Would anyone be able to help me? I am extremely puzzled about this inquiry. I am to a fantastic degree overpowered about this request.


    Any better idea would be highly appreciated.
    Thanks.

  2. #2
    wireweinie's Avatar
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    Not sure, exactly, what info you need on this. A standard relay is just an electro mechanical switch. It uses power, usually from a manual switch, to activate a magnetic coil. This coil will move switch contacts to make or break a circuit. The solid state relay (SSR) does the same thing. The only difference is that, instead of moving switch contacts to make/break a circuit, it activates a self contained, solid state circuit.

    The advantages are as you stated above. The relay is selected to handle the total current flow in the circuit to be controlled. It is then operated by much smaller wires and switches from a different location. An easy example of this is the master relay in an aircraft. In some aircraft, the master relay must handle 200 amps or more during startup. However the relay is turned on and off by a 20 or even a 22 gauge wire and a switch rated at around 5 amps maximum. This relay is usually mounted next to the battery while the control switch is mounted on the instrument panel.

    Theoretically an SSR can be used in place of most electro mechanical relays and I've looked into using them on aircraft with electrical noise issues. But they do have some draw backs. First off they are expensive compared to standard relays. Some of the higher capacity SSR's also need to be mounted in such a way as to draw off heat they generate during use. And when selecting one to use on an aircraft, take note of the voltage and current ratings to insure that you get one that will work correctly upon installation. I.e. lots of the SSR's I've looked at were either designed for to low a current capacity or were designed for AC circuits. Finding one that will work on 12 or 24 volts DC and at, say, 40 amps for a circuit such as avionics power is tough and the ones I've found many, many times the cost of a relay.

    If you are working on your own aircraft, you can look into using transistors instead of small relays for turning on/off circuits such as lights. Installed on heat sinks, many low cost transistors will handle up to 15 amps.

    Web
    Life's tough . . . wear a cup.
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  3. #3

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    Thanks for your kind reply!

    I think SSRs comprises a sensor which reacts to a proper information control flag, a strong state electronic exchanging gadget which changes energy to the heap hardware, and a coupling component to empower the control flag to actuating this switch without mechanical parts. I think I'm not going to wrong with selecting the Solid state Relay (SSR). Sorry for my bad English.
    Thanks.

  4. #4
    fobjob's Avatar
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    To emphasize one of Web's points, commercial SSRs usually have a fairly large voltage drop across their outputs, and I don't think you would like 9-11 volts on your 12-14 volt buss.....that is where all the heat comes from....

  5. #5
    Little_Cub's Avatar
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    We used SSRs in the past you can find pretty nice units at a good price, if they fail it's usually to the ON state so take that into consideration when selecting for your application.


    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by Little_Cub View Post
    We used SSRs in the past you can find pretty nice units at a good price, if they fail it's usually to the ON state so take that into consideration when selecting for your application.


    Sent from my iPhone using Tapatalk
    Hello Little_Cub, Thanks for your reply. Also, I was thinking I will use SSR instead of SSW. Can you please share some of the information or datasheet for my better idea. Thanks.

  7. #7

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    I use a mechanical master switch from Summit Racing. It can handle up to 300 amps I think, more then enough plus no coil energized/ drawing power if left on. Firewall mounted, inside, with a little pushrod going up to the panel, right next to my floorboard mounted EafthX battery, so very short wire runs. Light and simple, while providing the usual master switch function of killing all the aircrAft's wiring. When I switched over ( ha ha) to this simple system from a conventional master and a rear mounted battery ( under the pass seat anyway) the old stuff when all pulled out and on the workbench made a impressive pile as compared to the new parts and wires. I saved 13 lbs., Going from the traditional master and the old Oydessy gell cell, bit more then 13 actually, plus stronger cranking to boot.

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    Thanks for sharing your thought. Please let us your update here after using the master switch from Summit Raching.

  9. #9

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    Quote Originally Posted by Ariovaldo View Post
    Thanks for sharing your thought. Please let us your update here after using the master switch from Summit Raching.

    I switched over to the mechanical switch from Summit 3 years and over 600 hours ago, it performs as it should, not much else to say about it. Other then one day, after 8 days of no flying, I went out to the hangar and saw that I had left it "on", and it was a non issue as the engine fired right up. Back in the old days, I'd been grounded, as it was I went flying. Experimental Rans S-7S, but the same master switch approach would work on anything. https://www.summitracing.com/parts/fla-fr1003-2
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  10. #10
    Tom3holer's Avatar
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    I have two identical mechanical switches as radio master switches. It works, solves the sw failure problem, is cheap and easy to install.

  11. #11

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    Quote Originally Posted by Tom3holer View Post
    I have two identical mechanical switches as radio master switches. It works, solves the sw failure problem, is cheap and easy to install.
    Could you please share install guideline for my better idea? Thanks.

  12. #12
    Tom3holer's Avatar
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    I am not sure of your question. My reasoning is that for lower current requirements like a avionics master sw the use of a relay or ssr simply introduces more circuitry to fail whereas two quality master switches wired in parallel give excellent redundancy for very little cost ease of installation.

  13. #13
    wireweinie's Avatar
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    If cost and simplicity is an issue, just use a single switch breaker for your avionics master. Works the same as a mechanical switch. It also gives an amount of circuit protection.
    Life's tough . . . wear a cup.

  14. #14
    wireweinie's Avatar
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    Ariovaldo

    What circuits are you connecting to?

    Web
    Life's tough . . . wear a cup.

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