Nomenclature! After all of this discussion it sounds like “half wave load” is 
being used to describe a load that is only using one of the two 120 volt legs a 
standard 120/240 split phase inverter provides. That being the case the AC 
output current rating should be looked at. For example an inverter rated at 9KW 
might have a 37.5 amp max output current rating. That means the inverter is 
only rated to supply 37.5 amps per leg. So in other words 120VAC X 37.5 amps 
=4500 Watts, (at unity power factor) or 240AC X 37.5 amps =9000Watts (at unity 
power factor). If a load is connected on one of the two 120 volt line to 
Neutral legs and the current exceeds 37.5amps the load will exceed the inverter 
rating. If the power factor is not 1, then the output watts can be less than 
the output VA.. It is possible that what is being referred to as a “half wave 
load”  could more accurately be described as an unbalanced load. That being the 
case the total load on the inverter may be less than the specified load rating, 
but the load current on one “leg” maybe more than the inverter rated output 
current. If the leg currents are measured and found not be reasonably balanced 
it may be possible to correct the issue by re arranging circuit breakers in the 
MDP.
Pieter Huebner
Project Manager
Off Grid Enterprises


From: RE-wrenches <[email protected]> On Behalf Of Jay 
via RE-wrenches
Sent: Saturday, December 21, 2024 10:55 AM
To: RE-wrenches <[email protected]>
Cc: Jay <[email protected]>
Subject: Re: [RE-wrenches] 1/2 wave loads

I can’t remember if I sent the update.

We identified the load as a Japanese bidet. Once unplugged everything is 
working normally.

So whatever people want to call the 1/2 wave. It’s what multiple OEMS call it.

If I can find an oscilloscope I’ll send along what the wave form looks like.

Jay




On Dec 19, 2024, at 10:11 AM, Jesse Dahl via RE-wrenches 
<[email protected]<mailto:[email protected]>> 
wrote:
I think about resistive loads as “in-phase”. Half-wave seem like they would a 
load with a diode blocking one side of the waveform.
Sent from my iPhone


On Dec 18, 2024, at 3:03 PM, Jay via RE-wrenches 
<[email protected]<mailto:[email protected]>> 
wrote:

I will add that I’ve heard privately off list that it’s actually smaller loads 
that seem to be the issue.

And larger 1500 watt electric heaters seem to work ok.

I’m wondering if anyone else has come across this issue and I guess more 
importantly is there a fix?

Jay


On Dec 18, 2024, at 1:52 PM, Jay 
<[email protected]<mailto:[email protected]>> wrote:

Here is what I understand 1/2 wave loads to be.

As I understand it, Heater loads are the main issue.

Toasters, toaster ovens, hair dryers, aquarium/terraium heaters etc.

But if there are other things pls let us know

Jay


On Dec 18, 2024, at 1:34 PM, GLBCC via RE-wrenches 
<[email protected]<mailto:[email protected]>> 
wrote:

What is a half wave load?

On Dec 18, 2024 13:35, Jay via RE-wrenches 
<[email protected]<mailto:[email protected]>> 
wrote:

Hi all.

I’ve recently been made aware that the fortress inverter isn’t too happy with 
1/2 wave loads.

I’m wondering if this is an issue with the AIO or solark?

Thanks in advance

Jay
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