How to create a 'neutral' for an off-grid 1-phase inverter 1

[SolarTrap]

Hello all,

I am running a few household items with an off-grid inverter powered by solar panels. All is fine except my laptops. When I am using the track-pad the mouse cursor jumps around like crazy. Only if I am holding the laptop case with my other hand it works again.
I think I understand my this is happening: Even if the inverters grounding pin is connected to the ground there is no 'neutral' wire, so its basically 'L1 and L2' instead of 'L and N' and the potential is floating around.

Is there a way to pull that one line to neutral?

Many thanks in advance
Markus

 

[FreddyNurk]

At first reading the trackpad operation and any possible neutral interference would be two completely separate things. Laptops are normally powered by some sort of external power supply, its possible to get some sort of coupling but unlikely.
Can we assume that the issue is still present when the laptop is running on batteries?
For any further considerations we'd need to know what the output of the inverter is (and your location...), or at least some more details of your distribution.

 

[SolarTrap]

These are the 3 cases with the laptop:
-running on battery: no problem
-running with power supply plugged into wall plug: no problem
-running with power supply plugged into inverter: jumping mouse cursor

The inverter (pure sine wave model) is connected to SLA batteries and I am running a 50ft 3 prong cable to the laptop.

 

[waross]

First the misuse of the word "neutral". The neutral is the wire that carries the unbalanced current when a transformer is center tapped to provide two equal voltages, or the wire that carries the unbalanced current from a three phase circuit with three phases sharing a common wire.
A single phase, single voltage circuit has no neutral. That said, the common wire in a 120:240 volt service is called the neutral as it is connected to the neutral of the 240:120 Volt panel and wires connected to the neutral bus are called neutral wires even though they don't meet the strict definition of neutral.
The neutral in a residential circuit is characterized by having a connection to ground and for 120 Volt circuits is more accurately called the grounded circuit conductor.
The lack of a ground reference on either of the inverter lines may be causing your issues.
If one side of the inverter output may be safely grounded, that will emulate the common 120 Volt residential circuit and may cure the issues. If the inverter output is not allowed to be grounded on either line, your option is an isolating transformer with one side of the secondary grounded.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[SolarTrap]

Thanks for the detailed explanation. How do I know if the inverter output is allowed to be grounded?

 

[itsmoked]

The manufacturer should know if the documentation is that freaking bad.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[SolarTrap]

I am not able to find such information in the manuals. Is there a sort of 'test' that can be performed to find out if the output grounding is doable?

 

[SolarTrap]

I got it working: for safety and as an indicator for current flow I wired a 25W incandescent light bulb between one pole of the inverter output and ground. Now the jumping cursor is gone!
I am using a pure sine inverter so I doth know if this works for MSW as well but I might test this soon.

 

[itsmoked]

That's fairly clever...

Does the lamp light up? Full brightness?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[SolarTrap]

No, it does not light up - that would be rather bad!