| Author |
Message |
Glenn Williams (Glenn)
Registered Member
Username: Glenn
Post Number: 108
Registered: 6-2006
Posted From: 216.163.57.146
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 19, 2007 - 7:00 pm: | |
I've been reading old posts for quite a while on this and MAK and my head is spinning. I can't find anything that quite applies to the equipment I have. Here is what I have:
xantrex 4024
7.5kw genset
50 amp shore line
Todd Eng. PS450S transfer switch.
Now, I am aware of the ground lift/neutral lift issues and of the lack of neutral switching in the inverter and I will take the proper precausions. I also know about the delay time needed for the inverter if it is installed after the switching panel. The power switch says it has a 20 to 30 second time delay. So here are the quandaries:
The power switch recieves 3 power inputs, genset, shore line and inverter. This power switch says that the genset is the override mode, the shore line is the median mode and the inverter is the default mode. How should I use this based on my inverter selection? Would it be better to put the inverter upstream of the transfer switch instead? The reasons I chose this inverter is that it will automatically turn on the genset when it needs the power and I want to make sure I do not lose that function. As for size, it really is overkill for the little AC we use, EXCEPT that I want to use it to power up to 2 air conditioners while going down the road.
Once I get the transfer switch/order of input figured out, I need to consider my selection of distribution panels. I'd like as few panels as possible. I have read a thread about splitting the bus bar on the panel and using a breaker in the upper section of bar to send power to the lower end of the bar for the inverter loads. It is an interesting idea.
Our electric appliances are a fridge (propane for boondocking), microwave, small flatscreen tv, occasional laptop, roof airs (3, will most likely never run more than 2 at at time), electrical outlets, small bedside fan, nightlight. Mabe the occasional other small appliance (blender for mixed drinks...) So not a huge amount and none of these get used for long except the fan at night. I don't think a huge sub panel will be necessary. My lighting will be 12 volt pulled from my Vanner off of the house batteries as is the furnace and water pump. Hot water is by propane.
Another question about this panel - does it need to have a 50 amp breaker installed in the shore line before the panel input?
Based on this info, please help me with the details! I know enough to get me in trouble, and yet still know when to stop and ask directions! Thanks!
Glenn |
James Robinson (Jjrbus)
Registered Member
Username: Jjrbus
Post Number: 103
Registered: 12-2000
Posted From: 68.246.241.232
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 19, 2007 - 7:44 pm: | |
Here is a link to Gumpy's site.He has spent a lot of time and effort documenting his work. You may find some ansewers there and you can belive if Craing did it, it is done right!!
http://www.gumpydog.com/bus/site_map.htm |
Sean Welsh (Sean)
Registered Member
Username: Sean
Post Number: 689
Registered: 1-2003
Posted From: 67.142.130.35
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 19, 2007 - 11:17 pm: | |
Having an SW4024 and a four-wire shore cord and/or genset makes for a very, very complicated situation. I could spend hours here explaining why, but the bottom line is that there is no one "easy" answer to your question. There are probably as many ways to do it as there are members on this board.
If you really want, as you say, to use the automatic generator-start feature of the SW4024, but also still support a shore line with two hots, you are in for quite a challenge.
Here's how I did it, but there are also other ways:
http://ourodyssey.us/bus-e-ac.html
To speak to just a couple of your specific points: the 20-30 second "delay" your transfer switch documentation is talking about refers to a delay between when the generator starts and the transfer actually occurs. This is NOT the same delay the SW4024 documentation talks about, which says there must be at least 100 milliseconds (1/10th of a second) from BREAK on one source to MAKE on the other -- your transfer switch, unless it cost over $2,000, likely does not have this feature.
Regarding the input breaker -- you must have one, but the breaker at the campground pedestal will suffice for input protection on the shore side. You will only need a breaker on the generator side, which your generator also likely already has. That said, you need to ensure that the input protection on either input to the SW4024 does not exceed 60amps, and, of course, all wiring and components between them will need to be rated for whatever your maximum breaker size actually is. My generator, for example, has an output breaker of 70 amps, so I have an additional 60 amp breaker between that and the SW4024.
HTH,
-Sean
http://OurOdyssey.BlogSpot.com |
Glenn Williams (Glenn)
Registered Member
Username: Glenn
Post Number: 109
Registered: 6-2006
Posted From: 216.163.57.146
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 20, 2007 - 12:25 am: | |
James,
Grumpy's web is great! I'm not done reading it yet, but what he wanted is exactly what I was planning. I really think he puts things very clearly. Thank you!
Sean,
First, I have borrowed many old copies of Bus Conv. Mag and have always appreciated the quality and beauty of your bus. Now I must equally applaud your website!
Ed Rolle has send me diagrams on how to use my exact transfer switch in conjunction with the inverter. It will require the addition of another relay to handle the ground and neutral bonding issue with the inverter and should still keep all of the features of the inverter available. This requires some modification to the transfer switch as well. I am waiting to talk with him and I will as his permission to post his diagrams here. I
One of the most unique ideas I read in your site was the use of a separate tank for drinking water. I think I will borrow that plan. I have several (5) extra water tanks and and an extra pump that I could use. Thank you!
Glenn |
Ed Roelle (Ed_roelle)
Registered Member
Username: Ed_roelle
Post Number: 49
Registered: 3-2005
Posted From: 69.136.130.161
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 20, 2007 - 10:25 am: | |
Sean,
I had the same concern relative to the SW4024 documentation which says there must be at least 100 milliseconds (1/10th of a second) from BREAK on one source to MAKE on the other. As I remember, the 4024 Plus, did not have that requirement in their documentation. I talked with Xantrex and they said they found that the time delay was not required - at least on the plus model. I don't remember if it holds on all the others. When possible, it would be prudent to shut one source off before activating another, just to eliminate the potential failure modes, like sticking contacts.
Ed Roelle
Flint, MI |
Sean Welsh (Sean)
Registered Member
Username: Sean
Post Number: 690
Registered: 1-2003
Posted From: 72.171.0.143
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, November 20, 2007 - 9:07 pm: | |
Ed (and Glenn),
On the break-before-make issue, I have to say that the jury is out on how hard and fast this rule is. The SW4024 documentation clearly requires it, but, then again, that unit was really designed for grid-tie, sell-back applications, where the issue could be more serious.
I will note that Dick Wright, who is well respected in this community and also has many years of experience with these products, routinely installs an IOTA transfer switch (IOTA is basically the replacement for Todd Engineering, who no longer exist) ahead of the AC2 input to his SW-series installations. (Dick does not use the AC1 input.) Reportedly, Dick's installations have never had a problem with this, even though the IOTA's transfer in less than 100 milliseconds.
I tend to take a more strict interpretation of manufacturer's recommendations, especially where high-dollar items are involved. You wouldn't want to fry your expensive inverter and then have Xantrex tell you to pound sand because you hooked it up wrong.
FWIW and YMMV.
-Sean
http://OurOdyssey.BlogSpot.com |
|