No idea but somebody else will probably come along with a better idea then mine, seems a lot of these generators have this thing installed on them (Has $25 hard start kit). Not sure what it does or how it works. Strangely enough you said you use it for 240 volt. Looked at the picture and didn't see a 240 volt connection.
If you are using the what look like the 120 volt circuits you can't over load the unit. Maximum current draw will cause it to go into protection mode and shut down the power load. The following is an exert from the owners manual which I got from Yamaha's site. Link at the end of this post.
Hope this helps
Overload indicator light
The overload indicator light
comes on when an over-
load of a connected electrical device is detected, the
inverter control unit overheats, or the AC output voltage
rises. The electronic breaker will then activate, stopping
power generation in order to protect the generator and
any connected electric devices. The AC pilot light
(green) will go off and the overload indicator light (red)
will stay on, but the engine will not stop running.
When the overload indicator light comes on and power
generation stops, proceed as follows:
1. Turn off any connected electric devices and stop
2. Reduce the total wattage of connected electric
devices within the application range.
3. Check for blockages in the cooling air inlet and
around the control unit. If any blockages are found,
4. After checking, restart the engine.