Inverter Surge

BrianSun · February 2013

My Wagan 1000W PSW inverter surge and blew a fuse in my nubulizer, for breathing treatments. It rated for 1.9 amps, the fuse 5 amp, the inverter has worked in the past. The 200 amp/hr batteries were fully charged, connections clean and tight. I put a volt meter on each batter and both ends of the input wire. So I called them and they took the inverter back. The technician call and said the inverter was fine and try a modified sine wave and something about inductive loads. Something does not sound right. This is a really small motor.

Could this be a bad inverter and the technician is missing something?

BB. · February 2013

Re: Inverter Surge

It blew the 5 amp fuse in your 120 VAC input to the nubulizer--Correct?

It is possible for an inverter to "brown out" on the AC output when starting a motor--But a 200 VA motor on a 1kW/kVA inverter--Should not happen.

Did you get a chance to measure the AC output voltage (with and/or without load)?

Assuming 200 AH @ 12 volt battery bank--the nice "maximum" continuous load would be around (for a flooded cell battery bank):

200 AH * 12 volts * 0.85 inverter eff * 1/8 hour discharge rate = 225 watts AC continuous

And the nice maximum surge current would be:

200 AH * 12 volts * 0.85 inverter eff * 1/2.5 hour discharge rate = 816 Watt peak (starting surge)

The nubulizer running at 1.9 amps at 117 VAC:

1.9 amp * 117 VAC = 222.3 VA

Does not sound like an over-sized load.

Did you replace the fuse and try it again before returning the inverter (and check the AC output voltage)? Does not happen often, but fuses do sometimes fail for no apparent reason (fuses can also get stressed from earlier brownout or other issues--then fail for no good reason).

-Bill

westbranch · February 2013

Re: Inverter Surge

that is a lot of inverter for a 5A (110V? = 550 W) load. Does it have a sleep mode? Possibly a surge when it comes out of sleep?

hth

BrianSun · February 2013

Re: Inverter Surge

westbranch wrote: »

that is a lot of inverter for a 5A (110V? = 550 W) load. Does it have a sleep mode? Possibly a surge when it comes out of sleep?

hth

It has a wireless remote control but the inverter was turned on by switch.

BrianSun · February 2013

Re: Inverter Surge

Bill, yes the 5 amp fuse was in the nebulizer. The voltage without a load was all over 30v 112v and anything in between. I though I was getting a bad connection so I check my meter on the generator and it showed 112V. I assumed there was something wrong with the inverter, they gladly shipped it back and the technician called and said the inverter was fine and he tried his nebulizer on my inverter and it blew the fuse each time.

Until this incident the inverter worked good with the nebulizer and several other devices. Once a month or so I would test my little system, run my c-pap overnight or do a treatment with the nebulizer.

Thanks for your response, Brian

BB. · February 2013

Re: Inverter Surge

Check the DC wiring from the battery to the inverter. You need solid/bolted up connections (not jumper cable clamps). 5 amps at 120 VAC is over 50 amps at 12 VDC.

Otherwise, it could have been something inside the inverter--Would not be the first piece of electronics that (temporarily) fixed itself during the shock and vibration during shipping.

Generally, PSW/TSW (pure/true sine wave) inverters work a lot better than MSW with motors and many electronic power supplies. The Modified Square Wave (modified sine wave is marketing speak) can cause induction motors to use 20% more energy than TSW/sine wave input--excessive heat can cause the motors to fail.

Many small transformers/wall warts and DC power supplies do not like the sharp edges of the square wave. Probably 80% of equipment will work OK and 10% will fail before their time.

All About Inverters
Choosing an Inverter - Home Power Magazine

-Bill

Inverter Surge

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