Installing an Inverter

[senormechanico]

Originally Posted by sail2wind

OP here, will anyone please answer my question

You need to obtain an automatic transfer switch (ATS) with the current rating at least equal or greater than the maximum current rating of your shore power connection, i.e. 30 amps or 50 amps whichever it is.

The input from the shore power is directed to one input of the ATS, the output of the inverter is directed to the other input of the ATS.
The common output of the ATS goes to your AC panel's input.

When wiring the ATS input to the shorepower, make sure it's the one which pulls in the relays. Iow, when shorepower is turned on, you should hear the relay(s) click in the ATS. That way, when you are using the inverter, your batteries are not wasting any (admittedly a small amount of) power on relay windings.

Also, you need to have one AC outlet which never receives power from the inverter. That's the one which powers the battery charger. If you let the charger run from the inverter, all you will do is get a positive feedback loop, the charger will run flat out, the batteries will try to charge themselves and all you will accomplish is generating a lot of heat.

[bene505]

Originally Posted by Waterwayguy

Have a look at my site here, http://tinyurl.com/2dcwvop . Chuck

Waterwayguy,

great blog and write-up!

You said this:

...The green earth ground from both the shore power inlet and the inverter was run through our already installed galvanic isolator...

I would think that the galvanic isolator only has to go between shore power ground wire and the rest of the boat. If you also ground your inverter in front of it, you may be bypassing the galvanic isolator, as there is likely an common ground between the inverter and the rest of the boat.

Regards,
Brad

[AnchorageGuy]

Originally Posted by sail2wind

OP here, will anyone please answer my question

If you have had the chance to look at the link I posted for our Inverter install, it should have answered many of your questions. What specifically do you still need? Chuck

[AnchorageGuy]

Brad, all of the electrical feed earth grounds to the main panel go through the galvanic isolator and then on to the earth ground for the boat. This is not really necessary with an inverter, just my choice. The normal installation would connect the earth ground from the inverter at the transfer switch, but it makes too many and too large a connection for the switch I have used. By running to the isolator we are not bypassing anything. This is the only ground coming from the inverter.

[goboatingnow]

Originally Posted by DotDun

I don't like the idea of 'slamming' a different power source on any appliance that may be running during the transfer. I would rather the appliance loses power for a several seconds, eliminating any chance of problems with differences in voltage/freq/etc.

My goodness electronics engineering as witchcraft


I designed a three way auto switch system. Priority to shore power , timed delay switch over for generator, default on neither to inverter

I also switch the ground ( protective earth) as each source should only have such grounds returned to it. ( and it alone)

Dave

[DotDun]

Originally Posted by goboatingnow

My goodness electronics engineering as witchcraft.

The point I was making was to switch from generator to inverter in <50msec is not a good thing. My generator runs any where from 108v to 118v and 60hz to 63hz. I've seen switching power supplies (like those used on laptop computers) blow internal fuses when switched fast between 2 sources with up to 5% difference in voltage and frequency.

YMMV

[AnchorageGuy]

DotDun, That has little to do with the switch or the power source. When plugging in shore power, switching to generator, or switching to inverter, the main power and individual breakers need to be off until the source is connected, then each breaker needed, starting with the main, turned on one at a time. And they should not have a load on them until after the breaker is on. Chuck

[DotDun]

Originally Posted by Waterwayguy

DotDun, That has little to do with the switch or the power source. When plugging in shore power, switching to generator, or switching to inverter, the main power and individual breakers need to be off until the source is connected, then each breaker needed, starting with the main, turned on one at a time. And they should not have a load on them until after the breaker is on. Chuck

This is not in agreement with the inverter manufacturer. From their manual:

"When utility AC power fails, the transfer relay is de-energized and the load is automatically transferred to the PROsine inverter output within 20-30 milliseconds."

I agree with the sentiment of your statement, hence I don't let the inverter 'slam' the new power source on without a few second delay. My point is the designers of inverters with internal transfer relays don't agree with you and I.

[AnchorageGuy]

I do agree with that, which is why I always install an inverter with a manual switch. Chuck

[joey69]

Originally Posted by JDGreenlee

Reader also beware: IMHO some of these forums are seeded/salted (depending on your viewpoint) with vested interests and not all of them acknowledge their formal relationships with manufacturers or dealers all of the time. Most do. Some do not. Just sayin'... That said, it is value-added here for those having it to contribute hard data and to correct errors - but please reveal potential conflicts of interest, if any.

I AGREE 1 OUT OF 3 PEOPLE ON HERE SEEM TO BE SALESMEN OR COMPANY REPS.,THEY KNOW TOO MUCH TO BE EVERY DAY GUYS.

[goboatingnow]

This is not in agreement with the inverter manufacturer. From their manual:

"When utility AC power fails, the transfer relay is de-energized and the load is automatically transferred to the PROsine inverter output within 20-30 milliseconds."

I agree with the sentiment of your statement, hence I don't let the inverter 'slam' the new power source on without a few second delay. My point is the designers of inverters with internal transfer relays don't agree with you and I.

Sure you know better then the design engineers... go right ahead,

DotDun, That has little to do with the switch or the power source. When plugging in shore power, switching to generator, or switching to inverter, the main power and individual breakers need to be off until the source is connected, then each breaker needed, starting with the main, turned on one at a time. And they should not have a load on them until after the breaker is on. Chuck
__________________

This is impractical, not needed and has no basis in theory. Once the expected loads are within the invertors ability to handle there is no detrimental effect in switching over fast. Even if the load is in excess, the invertor fail safes should handle it gracefully. If not the design is junk.


Its amazing, whwn one is actually a professional to hear voodoo expressed as opinion, it worries me when I listen to other advice on topics that I dont know a lot about.

For thoese of you interested in switch bounce times and load surging during mechanical switch over do a bit of googling. It would of course be preferable to do zero crossing switch over ( primarily to prolong the switch life), its not really pratical or cost efficient.

The point I was making was to switch from generator to inverter in <50msec is not a good thing. My generator runs any where from 108v to 118v and 60hz to 63hz. I've seen switching power supplies (like those used on laptop computers) blow internal fuses when switched fast between 2 sources with up to 5% difference in voltage and frequency.

Most invertor switch overs actually can occur in a half cycle, often well less then 50ms. Nothing should fail on this , and if it does its a piece of junk.



Dave

[bene505]

When there's a power failure, inverters are running data centers, trading desks, and other very critical things. If they were to cause problems downstream from them, it would be very bad for the manufacturer. Of course, those aren't small marine systes, but the technology is there to do it right.

(Not to mention the quality issued I've heard about from reputable brands being offshored and now being made in China.)

Regards,
Brad

[senormechanico]

<Power goes out>

<Switches off all breakers>

<Switches off all loads>


"OK, all you electronics, don't worry. Everybody take a nap. We'll wake you up soon."

"Little inverter...Mister Powerman... wake up.. we need you. Good boy! Now we're going to give you a load. Aren't you a strong big boy! Here we go.. I'm SOOO proud of you !!

<Switches breakers on>
<Switches loads on>

Stuff runs normally.

[capn_billl]

Senormechanico has it right. DO you want to go fancy, or failsafe?

[goboatingnow]

Goodness Senormechanico, will all the pampering youre giving thoses electrons, how the hell am I going to get any work out of mine, soon theyll all be on your boat.!! Its a wonder your invertor actually wakes up at all,

Dave