sewing machines?

lazza
lazza Solar Expert Posts: 336 ✭✭✭
in Off Grid Solar & Battery Systems #1
Hi Forum

We recently had to go to one of our new off-grid installations because the Victron 2000VA inverter had shut down. It happened when the owner plugged in a sewing machine.

Now this installation has 900Ah (C100) of batteries, over 1kW of panels, and the owner who has been watching the voltage says it has never gone below 25V. We planned it this way, and in theory they should never have a problem with their system which should the batteries above 50% all the time.

THe inverter was programmed to switch off at 23V... The sewing machine is only 85W and I cant believe it caused such a large voltage drop to below 23V on start-up.

My only other thought is if it could be for DC voltage ripple, but new batteries shouldnt provoke this, should they?

Does anyone know why this may have happened? is there anything particular about sewing machines connected to an off-grid system that may cause issues?

Thanks
Larry
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: sewing machines?

    One thing I can think off--The old sewing machines that I am aware of used a brushed motor (universal AC/DC motor) and a reostat (variable resistor) for speed control... They produced a lot of radio frequency interference. Could it "confuse" the inverter?

    The other is that the sewing machine light was left on (7-10 watts?) and drained the system (along with other loads).

    Check if there is a short between ground and hot lead(s) and see if anything gets hot that should not.

    And the usual other checks--DC power cables/connections/battery bank/solar charging OK, no other phantom/excess load plugged in?

    Does the sewing machine+inverter work OK during day/now?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
    #3
    Re: sewing machines?

    The sewing machine is new and the inverter shut off instantly when the machine was switched on. The system was at 25V when the owner went to look at the batteries shortly afterwards- so drained batteries is out of the question.

    It may be more a case of radio frequencies confusing the inverter... dunno....

    I've told them not to use the sewing machine again, and the incident has not reoccurred--- thought there may be something special about sewing machines which could provoke this
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #4
    Re: sewing machines?

    I sew a lot of boat canvas with my machine and has never been a problem. Where and what was it plugged into. Could it be a outlet that is not on the same sub panel ground as the inverter or one that was missed during the install ??
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #5
    Re: sewing machines?

    My wife uses here Husqvarna on the Suresine 300 without any trouble.

    It is electronic control.


    (is that a true SW inverter?)
    Tony
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  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
    #6
    Re: sewing machines?

    Its TSW and sounds like i need to find out exactly how and when it happened, it could be that there is an electrical fault somewhere
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #7
    Re: sewing machines?

    I install Inverters in the Marine market. I usually am stuck with taking the main supply panel and splitting the buss's into Inverter and non-Inverter items, of course none are labeled on 50 different wires. Every once in a while I will miss a neutral or hot line and you'll get a fault or the Inverter will drop out if something is plugged in or turned on. Just a shot since it's a new install
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #8
    Re: sewing machines?
    lazza wrote: »
    Its TSW and sounds like i need to find out exactly how and when it happened, it could be that there is an electrical fault somewhere

    If it is a simple mechanical sewing machine (even one with fancy cams) there should not be any surge when you turn the unit on, just when you depress the foot control. And if you do that slowly, the speed control should minimize the surge.

    On the other hand if it is an electronically programmed (computerized) sewing machine the electronics are probably using a switching-mode power supply with a large input capacitor and no soft start circuit. This can cause a surge when first turned on which can trip the inverter. The surge will be particularly bad if you are using an MSW inverter, but can be very large for the first cycle even with PSW/TSW.
    You can find a varistor type soft-start device to plug the machine in through or you can wire the machine up with a manual series resistor which is switched out of the AC line after you have turned on the switch on the machine. If you cannot find anything off the shelf and are the experimenter type, take a look at http://sound.westhost.com/project39.htm. For this use case, I would leave out all of the fancy electronics and put in a manual switch which you hold in the momentary position to kick in the resistors or varistors and then release once the sewing machine is powered up.
    SMA SB 3000, old BP panels.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #9
    Re: sewing machines?

    Another thought, I had a customer that had a piece of my equipment that they claimed had a issue when plugged in. I sent them a new one and it had the same issue. I had them try different outlets, same thing. I got on a plane and flew 2000 miles just to find out they had a $10.00 power bar with a surge protector from Radio Shack that they had attached to the back of the machine and it was faulty. All they were doing was moving it around and the problem. Of course they never told me about the power bar, just that they knew it was my Machine because everything else worked.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #10
    Re: sewing machines?

    BlackCherry0 has a good one--Extension cords and power bars with surge suppressors.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
    #11
    Re: sewing machines?

    Thanks for your replies- If it was caused by a current surge.. then why didnt the 10A (at 230V) circuit breaker trip... or the 125A (at 24V) fuses between the batteries and the inverter blow.. when this inverter should take surges up to 150A (3600W)?
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #12
    Re: sewing machines?
    lazza wrote: »
    Thanks for your replies- If it was caused by a current surge.. then why didnt the 10A (at 230V) circuit breaker trip... or the 125A (at 24V) fuses between the batteries and the inverter blow.. when this inverter should take surges up to 150A (3600W)?
    Your thinking of it being like a current surge from a draw on the inverter. If the Inverter circuitry detects a feedback on the neutral, it will fault and / or shut it's self down depending on the inverter. At Least thats what I am thinking. Has it shut down with anything else plugged into that outlet ?? I would suspect that if some things were plugged in with reverse polarity that could cause it to fault. I use to have a old battery charger that would trip mine.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #13
    Re: sewing machines?

    Fuses/breakers are typically designed to allow surge current through. A 15 amp home breaker will allow well over 35 amps for a hand full of seconds before it pops.

    The electronics in inverters are typically much faster/more sensitive to "adverse" electrical conditions and will usually shut down an inverter before popping a breaker or fuse.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
    #14
    Re: sewing machines?

    Thanks Bill, that's very interesting and could explain what happened... although it's depressing to know that all my efforts to put in the best protection possible is somewhat in vain :)
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #15
    Re: sewing machines?

    No--You are still providing good protection... It is just that wire heating (I2R) is time dependent. Very short surges will not over heat a wire, but running 20% more current than rated for an hour may.

    In the US, the typical pole transformer for the final drop to a home is rated around 10,000 amperes maximum current (transformer will self limit to that maximum). Therefore, all primary fuses/breakers are rated to interrupt (AIC--Amps interrupting current if I remember correctly) 10,000 amps at 240 VAC.

    Your inverters are obviously never going to supply 10,000 amps into a short--So, the fusing/breakers tend to be useful for "somewhat" overloaded electrical circuit protection. I think you can buy digital breakers that can trip at set currents--But that would probably make standard surges trip breakers way too often and is really unneeded.

    If you have critical loads vs non-critical (say a shop--the lighting would be critical and the machinery not so much)--That way if a saw overloaded the inverter and caused it to shut down, the lighting inverter would still be up (don't want to be in the dark when saws and laths are spinning).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #16
    Re: sewing machines?

    It depends on the type of electronic machine, in this case sewing machine, can you mention the type of sewing machine, version, brand etc?
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  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
    #17
    Re: sewing machines?

    HI ChrisJay

    I dont unfortunately have any of that information- I will try and speak to the owner though in September to analyse exactly what happened

    Cheers
    Larry
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