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Thread: LED fixtures are fusing my relays

  1. #11
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    Jun 2010
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    Ask RAB for the maximum inrush information on the ballast used. This might not be part of the fixture's specs. RAB might get the info from the ballast manufacturer for you but keep in mind that if it's not part of the fixture's specs, it just happens to be what is is by the ballast used. A next batch of the same product with a ballast that is not of identical design can throw change it all. Different ballasts have a dramatically different inrush pattern. Common CFLs and some older LEDs have 10-15A inrush. The more common design has no inrush or only peaks at only a 2-3 times the rated current. The pop and spark you hear is actually switch eroding away.

    Gather a CFL you have sitting around and a common LED lamp with a similar real wattage, screw it in just enough for the base to make connection and come on. Loose and tighten around the marginal point. You'll hear the spark and sometimes smell it. They can be real, real, destructive.
    If you're curious: https://www.digikey.com/en/articles/...t-tribulations

    A SSR isn't considered a switch for safety purposes. You will have to de-energize the input to SSR before you can work on fixtures.

  2. #12
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    Quote Originally Posted by Visualize79 View Post
    The problem is, I'm cramped for space, I need something that's small and really low profile, hence the 12A ice cubes, really compact, what do you think about a solid state relay, they're fairly small and easy to get at 25 amp rating, I wonder if I'd have an issue with inrush on those


    Sent from my iPhone using Tapatalk
    The link is to a 3.5w x 5.5L x 3.5"h box and power relay up to 50a just to give you an idea what's out there. You could go def.purp., iec, .

  3. #13
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    Quote Originally Posted by sameguy View Post
    The link is to a 3.5w x 5.5L x 3.5"h box and power relay up to 50a just to give you an idea what's out there. You could go def.purp., iec, .
    Thanks


    Sent from my iPhone using Tapatalk

  4. #14
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    171231-1704 EST

    Visualize79:

    Do you play with (experiment) with electrical circuits?

    Do you have a scope, an RMS meter, an average reading meter, an electrodynamometer meter, a function generator, a voltage variable current limiting DC supply, incandescent bulbs, misc components, resistance box, capacitance box, transistors, FETs, Triacs, SCRs, small transformers, electrolytic capacitors, film capacitors, space heaters, and any other misc parts. If not you need some. Then you need books on electrical circuit theory, and start to play.

    What does some electrical rating mean? How would you create a rating for something?

    You have a problem to solve, but you lack knowledge about the components. You need to learn basics of electrical circuit theory, and how different components work.

    Because you have a switch rated at 10 A (what does that mean), and a load with a rating of 10 A (what does that mean), can you use that switch to control that load?

    I have some switches that are 90 years old, and still work. They were well designed, properly applied, and not used a lot.

    You are applying components that you really know nothing about, other than some box labels.

    Do you know that an electrodynamometer meter that reads 100 V on a DC voltage will read 100 V on an AC voltage that produces the same heat in a resistor that was produced by the DC 100 V?

    .

  5. #15
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    Quote Originally Posted by gar View Post
    171231-1704 EST

    Visualize79:

    Do you play with (experiment) with electrical circuits?

    Do you have a scope, an RMS meter, an average reading meter, an electrodynamometer meter, a function generator, a voltage variable current limiting DC supply, incandescent bulbs, misc components, resistance box, capacitance box, transistors, FETs, Triacs, SCRs, small transformers, electrolytic capacitors, film capacitors, space heaters, and any other misc parts. If not you need some. Then you need books on electrical circuit theory, and start to play.

    What does some electrical rating mean? How would you create a rating for something?

    You have a problem to solve, but you lack knowledge about the components. You need to learn basics of electrical circuit theory, and how different components work.

    Because you have a switch rated at 10 A (what does that mean), and a load with a rating of 10 A (what does that mean), can you use that switch to control that load?

    I have some switches that are 90 years old, and still work. They were well designed, properly applied, and not used a lot.

    You are applying components that you really know nothing about, other than some box labels.

    Do you know that an electrodynamometer meter that reads 100 V on a DC voltage will read 100 V on an AC voltage that produces the same heat in a resistor that was produced by the DC 100 V?

    .

    It is good to know the basics, such as load on a circuit/device. Also good to know the load capability of the device. However not everyone has the means to do the testing you are speaking of. Most electricians don't have a scope or much other "bench" testing equipment. Basic meters are all that's usually needed in the field.

    To a non-engineer, most of this is over our heads and is not something we have the means or time to test. We just want to know the basics, install & wire it.
    If you aim at nothing, you will hit it every time!

  6. #16
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    Little Bill:

    What I see as a problem is the lack of interest of persons in the electrical field of finding out the basics of how things they use work.

    An individual may have none of the various items I mentioned, but some can be easily obtained free, others at low cost, others borrowed, or temporarily used. Much can be learned from books.

    What I see is a lack of desire to delve into how things work.

    Consider an incandescent bulb. At a particular operating temperature it can be viewed as a constant linear resistance. If one has a DVM the room temperature (cold) resistance can be measured at essentially zero current with a Simpson 260/270 or Fluke 27 at about 10 ohms. By calculation at 120 V it is about 144 ohms. Lacking anything else one can make voltage and current measurements at other voltages by putting various combinations of of incandescent bulbs in series/parallel combinations in series with the bulb being measured. A Variac is easier.

    The peak possible inrush current to a 100 W incandescent at a cold turn on is about 170/10 = 17 A. Whereas steady-state RMS current at 120 is about 0.83 A. 1000 W of incandescent when turned on might be a peak current of 170 A. At turn on it also can be 0 A, but by the first voltage peak large, but not as large as the max peak that occurs when turn on occurs at the time of a voltage peak.

    How can you approximately measure this peak current without a scope. Use a current shunt of about 0.5 ohms for the 100 W bulb, a 1N4004 diode, a 25 ufd capacitor, a DVM, and many turn on tries to get a turn on time at a voltage peak.

    Basically there are ways to do a lot of study without a great expenditure of money. There has to be an interest.

    .

  7. #17
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    Quote Originally Posted by gar View Post
    171231-2107 EST

    What I see as a problem is the lack of interest of persons in the electrical field of finding out the basics of how things they use work.
    An individual may have none of the various items I mentioned, but some can be easily obtained free, others at low cost, others borrowed, or temporarily used. Much can be learned from books.
    What I see is a lack of desire to delve into how things work.
    Consider an incandescent bulb. At a particular operating temperature it can be viewed as a constant linear resistance. If one has a DVM the room temperature (cold) resistance can be measured at essentially zero current with a Simpson 260/270 or Fluke 27 at about 10 ohms. By calculation at 120 V it is about 144 ohms. Lacking anything else one can make voltage and current measurements at other voltages by putting various combinations of of incandescent bulbs in series/parallel combinations in series with the bulb being measured. A Variac is easier.
    The peak possible inrush current to a 100 W incandescent at a cold turn on is about 170/10 = 17 A. Whereas steady-state RMS current at 120 is about 0.83 A. 1000 W of incandescent when turned on might be a peak current of 170 A. At turn on it also can be 0 A, but by the first voltage peak large, but not as large as the max peak that occurs when turn on occurs at the time of a voltage peak.
    How can you approximately measure this peak current without a scope. Use a current shunt of about 0.5 ohms for the 100 W bulb, a 1N4004 diode, a 25 ufd capacitor, a DVM, and many turn on tries to get a turn on time at a voltage peak.
    Basically there are ways to do a lot of study without a great expenditure of money. There has to be an interest.
    .
    OP is faced with a dilemma with regard to “fusing” contact on his ice cube relays.

    He did not come here (I hope that's what he expects) for a lecture on the fundamentals of electrical /electronic engineering.
    While it is helpful for some who need some refreshers. . .I think that he wants a more discernible solution to his problem at hand.

    If that would have been the case (an in-depth) lecture he would have enlisted in a forum that deals with the vagaries of engineering textbooks.

    There's a few of them on the web.

  8. #18
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    Ann Arbor, Michigan
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    181201-1626 EST

    myspark:

    You are describing the welfare state. Provide someone a handout.

    This is the old fish story. A hungry person needs food. You can give him a fish, that is good for one meal. Teach him to fish and he can live without further handouts.

    We are not where the problem is, and we can't directly make measurements to try to find the cause. From our remote position we can only guess.

    Many people in many fields are encountering new products. We need to learn how these products work if we are to be efficient in troubleshooting problems.

    Screw-in LED replacrements for incandescent bulbs present all sorts of problems, such as --- RFI (radio frequency interference), flicker, dimmability, intermittent on-off, light quality, degradation of light with time, reliability, initial inrush current, repetitive in rush current, ambient temperature, and operation in a confined space. One needs to known about details that were not needed with an incandescent.

    A big enough relay will probably solve the problem. That is the easy remote answer. Is that the best solution?

    .

  9. #19
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    Windsor, CO NEC: 2017
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    Gar, you never teach a man to fish. You attempt to dazzle him with your brilliance as you recite every genus and species of fish to him while he starves to death. There's a time and a place for the knowledge you bestow on the forum, it would behoove you to be more selective.

  10. #20
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    Quote Originally Posted by Visualize79 View Post
    I have a gym that I set up with 20 RAB LED RAIL150W/D10 highbay fixtures, 153 watts per fixture, the fixture is rated for voltages from 100-277v 50-60hz, 0.9A per fixture, they are set up in 4 rows of 5 fixtures per row, each row is on a separate 208v single phase circuit, separately switched through a DPST ice cube relay, the relay is rated at 12A, 240, with a 120v coil.

    My problem is, I have been having a problem with arcing on the contacts as the relay opens and/or closes, seemingly excessive heat coming off of the relays and eventually getting fusing of the contacts on the relay, what could be causing this, thank you

    a quick and dirty that will probably work is RIB. 20A. contacts. latching. 12v secondary momentary contact.

    https://www.functionaldevices.com/pr...tails/RIBL12B/

    this one's 30 A. @ 300V.

    https://www.functionaldevices.com/pr...ails/RIB12P30/
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    ~~~~Please excuse the mess.~~~~

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