Re: [RE-wrenches] Inverter with no overload protection?

[Allan Sindelar]

Wrenches: Followup on my earlier post about the XP125: Dan at Exeltech has stepped up in a major way. Here are a few quoted excerpts from a set of emails he has sent me about this: 1. Cause and solution: Certain of the new electronic chargers (such as De Walt, Craftsman (usually made by De Walt, etc. and branded "Craftsman"), and others are highly capacitive on their input.  In certain instances, this can drive our voltage control loop unstable in the smallest inverters.  Anything that looks larger than approximately 1 microfarad might do this - but again .. only for our *smallest* inverters, such as the XP125 and XP250.  Our larger inverters (>600W) and our new designs do not exhibit this sensitivity. If any of our inverters are going to be used with a capacitive load, let us know and we will provide free of charge a component for to you to wire in series with the inverter AC output that will counteract the effects of a capacitive load. Also .. since a capacitive load appears to be the situation with your customer, please contact me at the office on Monday and I will authorize the repair of her unit free of charge.   We will also include the component (referenced above) for connection in series with the inverter when you re-install it. 2. What the fix is, and why it's done this way: In the case of the XP125 (sorry, no pun intended), there's not sufficient room inside the unit to add the inductor - hence external mounting and connection (anywhere you like).  You could install it into the "line" lead of a power strip and it will do the job perfectly.  Also .. there's an issue if we modify anything internal to the inverter.  It's UL Listed .. and if we even change the paint color .. UL gets involved.  If *we* install the inductor .. it affects our UL Listing.  If *you* install the inductor .. UL doesn't care.   #2: The inductor can be installed in the circuit used for any and all loads.  No need to have it carry the power for just the charger.  Install it inside the power strip, solder the inductor in series with the "line" conductor, then have that strip feed all of the loads that will ever be used, just as they're doing now.   #3: Unasked question: Why don't we do this for all of the inverters? First .. because this issue didn't become a problem until quite recently, and only then with some of the new electronic chargers.  Second .. the "fix" is needed only for a tiny fraction of the units we manufacture, and we're doing all we can to help keep the cost down for you and your customers.   Our higher-wattage inverters don't tend to be affected by electronic chargers because the charger's capacitance is a far smaller percentage of our large inverter's AC output capacitance (compared to the XP125), and thus isn't generally an issue.  The only time a larger (e.g. 1100 watt) inverter may be affected would be if you were to plug in [say] six to ten of these electronic chargers into that inverter all at once -- in which case the corrective action is an inductor (the same as for, but a larger inductor than for the XP125) .. and again one we'd provide free of charge. 3. About my Wrenches post that turned out to include incorrect information: The source of the misinformation has been found.  He was forced to eat liver-pate and peanut-butter sandwiches on raisin bread, while drinking warm milk and listening repeated renditions of the Macarena Song.   All kidding aside .. you spoke with a tech who started on the production floor and graduated into our Service Department.  He's actually very good at what he does, but like any of us .. not perfect.  He acknowledged telling you the information you reported on the Wrench BBS.  Turns out it was based on his opinion rather than fact.  The overload protection circuits in our larger inverters are obvious, as they involve [of course] more  [and larger] parts.  The 125, being comparatively low-power, has a physically smaller and less visible protection circuit (but being only 1 amp output, the circuit doesn't need to be very big).  Since the circuit didn't jump off the PC board to his eyes (so to speak).. he [unfortunately] presumed it wasn't there -- and that's the information he passed along to you.  He's been apprised of the correct info, and he expressed his sincere regret and apology for the inadvertent misinformation he shared.   I've instructed our Customer Service Dept to fix the inverter at no charge.  I'm doing this not because of your post on the BBS .. but instead, as you described it .. it's the right thing to do.  I will hope you'll be as vocal on the BBS about good service .. and also to correct/update the info to the Wrenches .. which I admit was passed along to you in error .. but only if YOU feel it's the right thing to do as well.  As we all know of our customers, happy ones don't tend to say much .. while the rare unhappy ones never seem to be quiet.   To that end .. If there's ever anything passed along to you from anyone at Exeltech that you question or make you go "hmmmmm" .. you are welcome and encouraged to contact me at any time for verification/clarification.  It's much easier to fix before it happens, rather than print the proverbial newspaper retraction, which never seems to get the high-level attention of the original erroneous story. So I am being "vocal on the BBS about good service .. and also to correct/update the info to the Wrenches". Exeltech is taking care of the issue in a good way. I'm happy to pass that news along to this list. Allan Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com -------- Original Message -------- Date: Sat, 10 Sep 2011 20:04:49 -0700 (PDT) From: Exeltech <exelt...@yahoo.com> EDITED: Hello Allan, and Wrenches ... On Sep 9, 2011, at 6:30 PM, Allan Sindelar wrote: > I called Exeltech tech support and was told that the XP125 > lacks protection against AC overload! This is not correct. Every inverter we manufacture .. from our 125 watt XP125 (the model your customer owns).. to our largest 120kW  208V 3-phase systems .. all incorporate overload AND short-circuit protection.  They are also all protected against over-voltage, under-voltage, and over-temperature. If you overload any of our inverters, they will limit their output current to a safe level.  If the overload is excessive, either in duration or wattage (relative to the inverter's rated output) .. the inverter will turn itself off. > There's no circuit breaker or internal shutoff protection, > and an internal fuse on the circuit board is included only > to protect against reverse polarity. This is also not correct. To reiterate, internal over-current protection DOES exist in the XP125 and all other models, regardless of wattage.  This protection is both electronic, and fused. While every inverter is fused - including the XP125, additional over-current protection should also be installed in the DC leads directly at the DC source - just as with any other inverter.  This protection can be in the form of fuses or properly-rated DC breakers. Due to the low wattage of the XP125, it's virtually impossible to blow the internal fuse due to overload.  The fuse exists to protect the DC wiring in the unlikely event of a short circuit in the inverter input circuitry.  The fuse does not protect against reverse polarity.  Should a unit be connected backwards and damage the inverter .. we typically repair it one time for this type of failure free of charge. > And because the inverter has been in operation for 15 months, > this apparent failure isn't covered under the one-year warranty. > Send it in, under $50 to repair. All of our out-of-warranty inverters are covered by a flat-rate repair fee, regardless of age.  We get units in for repair we made 20 years ago, and they get fixed and sent back.  Fact is, if the inverter is repairable .. we fix it and install any possible updates at that same time.  The cost is a flat rate, no matter what the failure, and this includes the updates.  This has been our policy for more than 20 years.  We occasionally get a unit that's been totally destroyed by lightning or other causes - which typically becomes an insurance issue.  In such cases, we work out a reduced cost for a replacement. > I wrote the customer about the load size and her (edited) > answer is below. Apparently it wasn't even an overload, > just a failure, possibly related to poor power factor in the > cordless drill charger. But I still have never heard of an > inverter without some form of overload protection, and it > seems to me that a unit this small especially needs it, > given how easily its capacity can be exceeded. This gets into a technical issue .. but one I'll describe in brief.  Certain of the new electronic chargers (such as De Walt, Craftsman (usually made by De Walt, etc. and branded "Craftsman"), and others are highly capacitive on their input.  In certain instances, this can drive our voltage control loop unstable in the smallest inverters.  Anything that looks larger than approximately 1 microfarad might do this - but again .. only for our *smallest* inverters, such as the XP125 and XP250.  Our larger inverters (>600W) and our new designs do not exhibit this sensitivity. If any of our inverters are going to be used with a capacitive load, let us know and we will provide free of charge a component for to you to wire in series with the inverter AC output that will counteract the effects of a capacitive load. Also .. since a capacitive load appears to be the situation with your customer, please contact me at the office on Monday and I will authorize the repair of her unit free of charge.   We will also include the component (referenced above) for connection in series with the inverter when you re-install it. --------- Regards to all... Dan Lepinski Sr. Engineer Exeltech On Sep 9, 2011, at 6:30 PM, Allan Sindelar wrote: Wrenches, A bit over a year ago I built a mini-system for a customer: One 135W module, SunSaver-10, 104 A/hr Concorde VRLA, Tri-Metric monitor and an Exeltech XP125 inverter. All but the module were installed in a plastic picnic cooler. The customer was totally satisfied with the system for this weekend getaway cabin system and used it well within its bounds - a couple of lights, mostly. Last week she called because the inverter had failed. I called Exeltech tech support and was told that the XP125 lacks protection against AC overload! There's no circuit breaker or internal shutoff protection, and an internal fuse on the circuit board is included only to protect against reverse polarity. And because the inverter has been in operation for 15 months, this apparent failure isn't covered under the one-year warranty. Send it in, under $50 to repair. I wrote the customer about the load size and her (edited) answer is below. Apparently it wasn't even an overload, just a failure, possibly related to poor power factor in the cordless drill charger. But I still have never heard of an inverter without some form of overload protection, and it seems to me that a unit this small especially needs it, given how easily its capacity can be exceeded. I have long respected Exeltech, one of few domestic electronics products left. But this incident is giving me pause. Morningstar's SureSine claims extensive protection: "The SureSine has extensive electronic protections that will automatically protect against faults and user mistakes such as short circuit, overload, high temperature and low voltage disconnect. Recovery from most faults is automatic." It's looking better all the time. Has anyone else experienced a similar failure? Thank you, Allan

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