suresine 300

ws9876 · May 2015

just to be sure...the Morningstar 300 watt sine inverter has an internal bond of neutral and ground...it looks to be that way from the brochure, a line connecting the neg and ground,...yes???
so if running the 120v output,+/- to a regular split phase breaker panel (offgrid,no grid), I should break the neutral/ground bond in the panel..yes??

or since this is 120 single phase it doesnt even matter...?????

and because its more convenient I could ground the inverter to a separate ground rod near the inverter and not use the mains ground rod. yes??

just trying to get this understood..

BB. · May 2015

The Suresine diagrams I remember, the AC output is floating and you pick one output (does not mater which--as far as I know) to tie to chassis/earth ground--And that wire becomes the white/neutral AC connection.:

http://support.morningstarcorp.com/wp-content/uploads/2014/07/ALL.DIG_.Correct_Inverter_Wiring.01.EN_.pdf

For such a small AC inverter--You really do not need to ground reference either output for most applications (some florescent tube lighting won't start without a neutral/earth bond; some electronic spark propane/natural gas lighting systems use the neutral/earth bond to work correctly).

-Bill

waynefromnscanada · May 2015

BB. wrote: »

The Suresine diagrams I remember, the AC output is floating and you pick one output (does not mater which--as far as I know) to tie to chassis/earth ground--And that wire becomes the white/neutral AC connection.:

http://support.morningstarcorp.com/wp-content/uploads/2014/07/ALL.DIG_.Correct_Inverter_Wiring.01.EN_.pdf

-Bill

That is correct. With both of my Suresine inverters, I connected a wire from the inverter ground terminal (which was properly grounded) to one of the AC output terminals, thus making that AC line "neutral".
Not being an expert on lightening damage, I can't say which would be the best place to connect neutral to ground. I did it at the inverter, hoping to reduce any induced voltage spikes between the inverter's transformer secondary windings and the primary windings, where a flash-over could take out the electronics.

ws9876 · May 2015

if you look at the company info it shows a bond in the inverter. Look at their site. so its already done inside.
The question is do I untie the service panel bond????? and is there any problem with using a separate ground rod for the unit ????

BB. · May 2015

Do you have a link to the documentation? Everything I remember seeing has an external neutral/chassis/earth ground.

Grounding/ground rods/etc.... I suggest that all electrical stuff "in the same area" be connected to a common ground point--Whether that is a single ground rod, or 6 awg wires running to a common bus, then connected to one (or more) ground rods--Is usually OK.

Ground Rods do not have very good connection to "earth" (as bad as 25 ohms). Connecting all of the chassis/safety grounds to a common point means that you have a low resistance connection that will be able to pop a breaker/fuse.

Connecting to the copper cold water pipe means that all of the plumbing (gas fixtures, stove, etc.) are also "at ground" so that they too can "trip a breaker/fuse" if hot wire hits them.

The ground rod--Really for a place for lightning surges to go (and if you have utility power, a place for a 12,000 volt line cross to go and trip their breakers).

-Bill

ws9876 · May 2015

i emailed Morningstar....
regarding ground rods.... I put a 2nd one in because I thought it would be convenient for solar panels,wind turbines later and chassis grounds....
but you are saying if you use the service panel ground you will trip a breaker faster and that might save wear and tear on stuff??
it was a lot of work to get that 2nd rod in the ground....

BB. · May 2015

For lightning protection, a ground rod near the "device" (solar panel racking, wind turbine tower, etc.), yes having a local ground rod can be very helpful. Lightning wants short+straight paths to earth ground. Do not run (for example) a ground wire from the solar array frames down through the middle of the house to the ground rod (under house, or next to foundation/AC main panel ground rod). Bringing lightning, in my humble opinion, into the home is not a good thing.

However, if you have a ground rod at the south end of the house (for solar array) and another at the north end of the house (for AC main panel/battery/inverter/etc.)--My suggestion is to connect both ground rods together with a #6 AWG cable. That way, if there is every a 12/24/48 VDC or 120/240 VAC short somewhere, the 6 AWG ground tie cable will ensure a quick breaker trip.

It is possible, for example, to connect a ground rod to a 120 VAC hot circuit and not pop a breaker--But instead just waste current and heat the earth around the rod:

120 VAC / 25 ohms = 4.8 amps

-Bill

waynefromnscanada · May 2015

ws9876 wrote: »

if you look at the company info it shows a bond in the inverter. Look at their site. so its already done inside.

If this is true, then they have made a change during production, because the two I have are definitely not bonded inside from the factory. I had to add the grounding jumper and I could use whichever AC output terminal I wanted to as "neutral". If you look at this company info link provided by BB, you'll see the external grounding jumper as installed by the customer. http://support.morningstarcorp.com/w...ing.01.EN_.pdf
Likewise, if you check out the installation and operation manual by clicking on DOCUMENTS in the following link, you will also see that the bonding of ground to one of the AC outlet terminals is external, done by the customer, not at the factory: http://www.altestore.com/store/Inver...60Hz-UL/p6994/

ws9876 · May 2015

this is from Morningstar....just for future reference..

TheSI-300 does not have an internal neural/ground bond. The Ground connection is isolated from the positive and negative DC terminals, and is also isolated from both the AC output terminals. The AC output is isolated, therefore AC Line and AC Neutral are interchangeable. The earth-grounded leg defines the AC Neutral. (see the Note on page 7 of the manual)

Ethan Brush · May 2015

ws9876 wrote: »

this is from Morningstar....just for future reference..

TheSI-300 does not have an internal neural/ground bond. The Ground connection is isolated from the positive and negative DC terminals, and is also isolated from both the AC output terminals. The AC output is isolated, therefore AC Line and AC Neutral are interchangeable. The earth-grounded leg defines the AC Neutral. (see the Note on page 7 of the manual)

Right. So just to be clear, the correct installation is to run the two ac conductors back to the panel and choose one to be the grounded conductor ("neutral"). Land the neutral on the neutral bar and make sure to install the main bonding jumper in the panel (usually a green screw). Run a bonding jumper from the neutral bar back to the inverter "ground" terminal. Connect your grounding electrode system to the neutral bus in the panel. You need to install a jumper to energize both phases in the electrical panel, unless you dont need many spaces and can deal with every other slot.

Remember that despite the name, "grounding" is mostly about interconnecting everything together and back to the source - the dirt has relatively little to do with it. That ground terminal on the inverter is to connect back to the source, not for sticking in the dirt. Installing a ground rod to a single piece of equipment does nothing, in fact is more likely to do harm than good. Everything below the ground (rods, pipe, ufer, etc) connects together, everything above the ground connects together, and single connection between the two is usually the best practice. Hope that helps.

suresine 300

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