MSW Interter

[Curt Sprenger]

Has anyone installed an Xantrex RV3012M unit in their coach? Any issues after the install with appliances, digital clocks/panels, line noise, other?

Thanks.

Curt Sprenger

1987 PT38 8V92 "MacAttack Racing"

Anaheim Hills, CA
Read all about Southwest Bluebirds and Friends (SWBB) at http://www.SOUTHWEST-BLUEBIRDS.ORG ...Then Join us.

"Host of the Annual Bluebird Quartzsite Rally"

[freewill2008]

Curt - I see this is the old Trace inverter line which was bought up by Xantrex.
Its a "modified sine wave" inverter, so the output has some square wave
characteristics.

We use a different Xantrex modified square wave inverter - the Freedom 1500
(another line bought by Xantrex). It makes the microwave sound funny and the
toaster buzzes a bit but everything works fine. For the TV, DVD, computer, and
other fussy electonics we use a Xantrex 400 true sine wave inverter which works
out great.

Lots of times a modified square wave inverter will run electronics fine, but it
depends on the particular device being powered so its not always predictable.

Be sure the DC wiring can handle around 300 amps. If the new inverter replaces
an existing inverter of the same size, the existing cables should be fine. For a
round trip of 25 feet to the batteries, 2/0 cable would be about right.

Bob Griesel '84 FC31 WLII WA
>
> Has anyone installed an Xantrex RV3012M unit in their coach? Any issues
> after the install with appliances, digital clocks/panels, line noise, other?
>
>
> Thanks.
>
> Curt Sprenger
> 1987 PT38 8V92 "MacAttack Racing"
> Anaheim Hills, CA
> *Read all about Southwest Bluebirds and Friends (SWBB) at
> http://www.SOUTHWEST-BLUEBIRDS.ORG ...Then Join us.
> "Host of the Annual Bluebird Quartzsite Rally" *
>

[Pete Masterson]

Most electronics covert 120 vac to 5 (or so) vdc current. The problem is less a matter of the electronics as it is the ability of the power supply to deal with the conversion.

The exception is electronics that have small electric motors -- for example a computer printer. Most work very poorly, if at all, with modified sine wave inverters.

I've used Uninterruptible Power Supplies with my multitude of computers for years. These are, essentially a small 12 vdc battery and an inverter. The inverters are all modified sine wave type. Even though I have UPS with sufficient power to handle a laser printer, no laser printer I've tried has ever worked with the UPS.

True analog sine wave power is a smooth cycle of the AC power. A graph of the wave shows simple curved lines. The power "swings" from side to side in a smooth transition.

A square wave (as displayed on an oscilloscope), digitally created, AC power is "instantaneously" switched in the alternating flow of AC. Electric motors simply won't run with this kind of power and many appliances that do run, might vibrate or buzz. Lights will work, but might buzz or even flicker (at 60 cycles per second). Square wave digital power is rarely used.

Modified sine wave inverters perform the switching in 3 or 4 steps making a blocky, stair-step wave on an oscilloscope. Most appliances can deal with this well enough. Most electric motors will run, though inefficiently, generating more heat (and drawing more electricity than normal).

"True" sine wave inverters aren't that different from modified sine wave, but the steps are 'chopped up' more finely -- in dozens or even hundreds of steps -- to more closely match the analog AC wave form. While there is a bumpiness to the wave, the steps are so small that they are treated almost the same as the analog wave form. For example, electric motors will operate efficiently with littledetectibledifference from a "real" analog sine wave AC power as received from a central power station or generator.

Pete Masterson

'95 Blue Bird Wanderlodge WBDA 42

El Sobrante CA

"aeonix1@mac.com"

Photos:

http://picasaweb.google.com/Bluebirdzoom/PeteMasterson#

On May 11, 2009, at 2:25 PM, freewill2008 wrote:

<snip>
Lots of times a modified square wave inverter will run electronics fine, but it depends on the particular device being powered so its not always predictable.

<snip>