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[mike]

So I thought you might enjoy my fiasco today!

Electric goes off at 7am.  Can't shower for work, can't make oatmeal.  So think, this is a great opportunity to test my new fangled INVERTER GENERATOR!  3kw/4kw peak.  Turn off 220v main to house from street.

Go to workshop, fire it up, try to plug it into my welder outlet and find it is wrong 220v plug.....  OK, no problem, I will move it around to side of garage and plug it into the GMC motor home outlet instead.  That works!

So it starts up and starts oscillating up and down in speed, little red light on it say overload on and off about once a second as speed goes up and down... Hmmmm not good.  So figure ok, will run into the house and look at what it is doing.  WOW!  lights going up and down once a second.  Vickie says she just shut off the 4 ceiling fans as they were going like 27,000 rpm and she thought they were going to launch themselves!  Run back out to shut it off, but hear it shut itself off on overload.

OK, well THAT didn't work....

Go into garage/office, smell burnt electrical stuff...  OH OH....

same in garage.....

same in house, kitchen specifically....

IN the end, I find I toasted:

    Our 20 year old above stovetop built in GE 900 watt microwave
    The toaster oven seems to have thrown off its internal MOVs - there is black soot under it on the counter top and it smells too - but it still works fine.
     The GOOD automatic smart golf cart battery charger in the garage
    A couple X10 noise filters in the garage/office
    A few X10 appliance modules, at least one RF xcvr unit
    A plug in rodent noise maker box melted its top case plastic, it is black, and it stinks now - I think flames came out there
    ALL 5 cool remote control X10 fancy light switches around garage and office
    my workshop computer power supply is dead

Not sure what else I will find, but I DID learn a nifty lesson:  TURN OFF BREAKER TO HOT TUB AND WATER HEATER BEFORE TURNING ON  GENERATOR.

I THINK that was my overload.  But can't be sure until I try it next time.....  Needless to say, I am writing a nice instruction sheet to attach with a string to the generator, with the notes of what to turn off before plugging in the generator, next time.

Until then,  bye

[Brian H]

Sounds like you got 220 volts into the 120 volt circuits or the neutral was missing. Forcing the loads to try an balance themselves.

I have a manual transfer switch so I can't possible feed the generator back into the power company feeds. Then I turn Off all breakers and only turn On the loads I need.

[bcwmachine]

Motor home outlets are quite often wired differently than you would think. Not 220 vac but two 110 vac same phase.
Best plan is to install generator outlet.
Bruce

[beelocks]

Not to mention illegal in most states.
Install a real transfer switch.

Fancy Inverter Generator $2000.
Proper Transfer Switch Setup $200.
Installation by a real electrician $300.
Frying everything electrical you own just to save a buck, priceless

[mike]

Thanks for all the replies!

NO, did not get 240 into the 120 circuits though.  As an electrical engineer I thought I could wire my own house when I built it 30 years ago.  Sorry if that put an electrician out of work for a couple weeks - you might be able to tell I don't support unions...  I don't remember all the individual wires I put in, but I do recall distinctly the motorhome outlet wiring.  Plain 'ol 240 with neutral.  I continue same wiring  on to the barn for 240 out there.  So not a plug compatibility issue this time.

If I ever figured on someone else trying to hook up the generator, I definitely would put in a xfr switch;  did that for my aged dad years ago - nice extra panel with automatic xfr & bypass switches and all to pick which circuits to energize and which to ignore.  My transfer switch now is a note attached to generator handle saying to shut off the breakers I don't want on...

What I learned too was these new inverter model (no generator) units can go very unstable and output excess of 300v easily!  Never had this issue with the older gen set. 

Once I cut out the shorted MOV's I am back running most stuff, but not the X10 units - at their price I just threw them away and replaced them from my stash.  Yep, sometimes saving a buck is not worth it.

Sure hope the day doesn't come when they make wiring your own home illegal!  We have enough to fight with those in Washington whittling away at our second amendment rights! 

[JeffVolp]

As an electrical engineer I thought I could wire my own house when I built it 30 years ago.

Except for what was required to receive an occupancy permit, I did that myself here (with the transfer switch).  And framing, 4 more zones of HVAC, plumbing, sheet rock, skim coat, tile, and finish work.  The only problem on inspections was one thing I had to fix that the original builder had done wrong.

Jeff

[mike]

Me too!  I passed plumbing inspection first time, occupancy permit thing no problem, but flunked the electric permit first round of all things!  They didn't like that I used my own grounding scRews in the  metal outlets - I had to replace them all with GREEN colored ones!

btw, good job jeff!  Good design!  YOUR repeater is still working fine!  I just discovered late yeasterday my AHP pro is not working, neither is my other RF xfmr (forget who makes it right now).....  HOpefully the AHP pro is just a shorted diode or MOV too;  will get into it tonight....

[dave w]

I will move it around to side of garage and plug it into the GMC motor home outlet instead.  That works!

I THINK that was my overload.  But can't be sure until I try it next time.....  Needless to say, I am writing a nice instruction sheet to attach with a string to the generator, with the notes of what to turn off before plugging in the generator, next time.

So the Motorhome outlet is a 240V 50 amp and not 120V 30 amp?

If you did not get 240V in your 120v circuits, then it sounds like your generator was seriously over shooting it's normal output voltage in the overload condition. Seems a little improbable with a hot tub and water heater connected to a 3kW genset. I am intrigued. 

[mike]

So the Motorhome outlet is a 240V 50 amp and not 120V 30 amp?

If you did not get 240V in your 120v circuits, then it sounds like your generator was seriously over shooting it's normal output voltage in the overload condition. Seems a little improbable with a hot tub and water heater connected to a 3kW genset. I am intrigued.  

correct.  Due to all the questions about 240 into 120, I decided to quadriple check myself.  

I turned on generator with cord plugged in and measured my 3 pins:  244 across main two, 122v from each to neutral pin.

I measured matching voltage on house motor home receptacle:  244v between the 2 main pins, 122v each to nutral pin.

So I think lesson is clear:  BEWARE new fangled INVERTER style generators:  If overloaded, they do not simply sag the generated voltage but instead wildly swing it from low (lights dimmed) to really really high.  I since found hot tub dead (.5amp fuse on main pcb - with MOV on other side), my AHP controller dead (#32 wire 'fuse" gone and MOV popped open), my V572RF32 non functional (its x10 interface also had its #32 'fusable link wire' gone and popped MOV), workshop computer PS dead although all MOVs looked good.  Quite an experience!  

If it surges ONE time, KILL it immediately!

I'v replaced some of the MOVs since I have them in my stock pile, but did not bother replacing all of them.  Seems MOVs like this today are next to useless.

[Brian H]

Gee you would think any good electrical engineer. Would design their product to not go wild on a severe overload and just peacefully shut down.

As you found out. A MOV is designed to absorb a certain surge current. Constantly hitting them with large voltage spikes. Will cause them to exceed their life span.

[JeffVolp]

I'v replaced some of the MOVs since I have them in my stock pile, but did not bother replacing all of them.  Seems MOVs like this today are next to useless.

The purpose of a MOV is to prevent damage from a high voltage transient.  Most transients are voltage spikes that do not contain much energy, but the voltage can be enough to cause damage.  When a transient has more energy than the MOV can absorb, it normally becomes a low resistance to pop the fuse to still protect the equipment.  In that case both the fuse and MOV should be replaced.  I have replaced a number of shorted MOVs, but only one that was open circuit from being blasted right off the PCB.

Jeff

[mike]

As you found out. A MOV is designed to absorb a certain surge current. Constantly hitting them with large voltage spikes. Will cause them to exceed their life span.

And many times go BOOM!  hee hee!  the little ones (1/4"dia) like in all the X10 units go "poosh" and let a little smoke out, the 1" and 1.5" dia ones go "BANG," let out a lot of burnt ele smell, and light up like lightning strike and send sparks a fly'in out the grill (if an opening is available)!  And do it multiple times until blown to smitherines!  Got 2 good bright sparky shots off both the golf cart & microwave units!  Of course second time was re-applying power one thing at a time so I got to experience them up close and personal!

[mike]

I'v replaced some of the MOVs since I have them in my stock pile, but did not bother replacing all of them.  Seems MOVs like this today are next to useless.

The purpose of a MOV is to prevent damage from a high voltage transient.  Most transients are voltage spikes that do not contain much energy, but the voltage can be enough to cause damage.  When a transient has more energy than the MOV can absorb, it normally becomes a low resistance to pop the fuse to still protect the equipment.  In that case both the fuse and MOV should be replaced.  I have replaced a number of shorted MOVs, but only one that was open circuit from being blasted right off the PCB.

Jeff

It worked as designed on the hot tub thank goodness;  had a 1/2amp fuse in front of it so it popped and even saved the MOV.  1/2 of the x10 modules did ok too I guess, as it blew away the 'fuse' which was a really tiny hair thickness wire jumper.... about 1/2 of them hung in there, the other half of em (7-8?) survived with new fuse, and 4-5 I just tossed.  Luckily the AHP, & V572 both were repairable. 

[dave w]

So the Motorhome outlet is a 240V 50 amp and not 120V 30 amp?

If you did not get 240V in your 120v circuits, then it sounds like your generator was seriously over shooting it's normal output voltage in the overload condition. Seems a little improbable with a hot tub and water heater connected to a 3kW genset. I am intrigued.  

So I think lesson is clear:  BEWARE new fangled INVERTER style generators:  If overloaded, they do not simply sag the generated voltage but instead wildly swing it from low (lights dimmed) to really really high.  

Mike, unless your generator is made by Yugo Motors, I think you have a bad one. I can't imagine any company not putting in some over voltage protection.

H-m-m-m I wonder if this was a frequency problem?

[mike]

fancy yamaha