XW5548 inverter: 150 amp fuses big enough?

[hammick]

I used 150a Blue Seas terminal fuses with my Conext SW4048 (yes on both + and - terminals as batteries are not grounded). That inverter exploded so Schneider upgraded me to an XW5548. Specs listed below. Do I need to get bigger fuses or is 150a big enough? My battery bank is 325ah L16 Trojans (48v). 10' 4/0 cables. Off grid system. 5kw genset. Thanks.

[Sunking]

What specs?

Maximum continuous current is 150 Amps. That means a 150 / .8 = 187 amps.

200 amps is what I come up with but as always Hammick do not ask us. Ask the manufacture.

One thing that scares me is just how do you plan to terminate the cables, and what size do you plan on using?

[hammick]

Looking back at Sunking's 150a recommendation for my SW4048 inverter I think I need 225a fuses for the XW5548.

Here are my calculations using the 7000w 30 min overload spec and 90% efficiency.

7000 watts / .90/ 48 volts x 1.25 = 202 amps.

Or should I use the 9,500w 60 second overload spec? This would require a 275a fuse

[hammick]

What specs?

Maximum continuous current is 150 Amps. That means a 150 / .8 = 187 amps.

200 amps is what I come up with but as always Hammick do not ask us. Ask the manufacture.

One thing that scares me is just how do you plan to terminate the cables, and what size do you plan on using?

Schneider will tell me that fuses at the battery terminals are not required. Went through that with them on the SW4048 install. They only require the 250a DC breaker in the panel. Decided to follow your advice instead and fuse at both battery terminals.

I will be using these fuse holders: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I bought pre-terminated cables. They will attach to the fuse holders.

[Sunking]

You use the maximum continuous load which is 150 amps. It is in your specs I looked it up. Ok having said that does not mean you you even need to use Maximum. You could use 10 amps. as that would be more than safe. Would not work real good but safe. OK?

OK let's back up a second. The most common type breaker you will fin din any home is 20 amps. If you run 20 amps continuous eventually the breaker is going to operate as any thermal fuse or breaker is not designed to operate at maximum rating.

OK for continuous loads which is really unrealistic in your application, you have to derate to 80%. Going back to the 20 amp breaker is 16 amps continuous. Look at any 120 volt appliance and you will not find any UL devices rates of 120 volts x 16 amps = 1920 watts, 2000 watts tops like a toaster oven or blow dryer.

So if continuous load is 150 amps (@ 48 vdc) continuous is 7200 watt input, way more than enough for 5500 watt Inverter. 150 / .8 = 187.5 amps. You woul duse 190 or 200 amps and that is overkill. If I were your contractor I would use 150 amps. document it, and have you sign off on it If you were to change that to something higher, and something happens would be all on you.

Don't take me wrong, but you are pushing the limits and are not gaining anything. You want to have the fuse operate prematurely to save your equipment. Even at 150 amp fuse if you blow it is pushing the system to extremes.

[Sunking]

Schneider will tell me that fuses at the battery terminals are not required. Went through that with them on the SW4048 install. They only require the 250a DC breaker in the panel.

That is really scary, get that in writing and you have an open and shut case in court if something happens. They would do everything they can to keep it from going to court.

[Mike90250]

The spec did not show in your post
What does the mfg call for ? Thats what you should use. You "could" go smaller, but run the risk of a surge, from a fridge compressor or something, starting up, blowing the fuse, The large breaker they called for on my install, will handle surges (and that inverter has a HUGE SURGE capacity) but still trip. If they call for a 250A breaker, you need to use wire rated for 250A, and terminations, Deviating from the recommended layout will result is less satisfactory performance,

[hammick]

You use the maximum continuous load which is 150 amps. It is in your specs I looked it up. Ok having said that does not mean you you even need to use Maximum. You could use 10 amps. as that would be more than safe. Would not work real good but safe. OK?

OK let's back up a second. The most common type breaker you will fin din any home is 20 amps. If you run 20 amps continuous eventually the breaker is going to operate as any thermal fuse or breaker is not designed to operate at maximum rating.

OK for continuous loads which is really unrealistic in your application, you have to derate to 80%. Going back to the 20 amp breaker is 16 amps continuous. Look at any 120 volt appliance and you will not find any UL devices rates of 120 volts x 16 amps = 1920 watts, 2000 watts tops like a toaster oven or blow dryer.

So if continuous load is 150 amps (@ 48 vdc) continuous is 7200 watt input, way more than enough for 5500 watt Inverter. 150 / .8 = 187.5 amps. You woul duse 190 or 200 amps and that is overkill. If I were your contractor I would use 150 amps. document it, and have you sign off on it If you were to change that to something higher, and something happens would be all on you.

Don't take me wrong, but you are pushing the limits and are not gaining anything. You want to have the fuse operate prematurely to save your equipment. Even at 150 amp fuse if you blow it is pushing the system to extremes.

I like your answer Sunking because I have four of the 150a Bussman fuses. I will use these. Obviously they are more than enough for charging. If I ever blow them with a load I'll go up to 175a or 200a.

I would also like to minimize any chance of going through the extreme hassle of having an inverter grenade. Been there already. The 150a fuses should help along with not shutting off the genset when the washer and dryer are running.

BTW Blue Seas terminal fuses are made by Bussmann and you can get them at Summit Racing for under $6

https://www.summitracing.com/parts/b...f150/overview/ (the product picture is misleading; they do not come with the fuse holder; those are made by Blue Seas).

[inetdog]

Schneider will tell me that fuses at the battery terminals are not required. Went through that with them on the SW4048 install. They only require the 250a DC breaker in the panel. Decided to follow your advice instead and fuse at both battery terminals.

What size are the preterminated cables?

The reason that you should ignore Schneider's advice is that their sole concern is protecting the inverter.
The purpose of the fuses at the battery terminals is to protect you, the wiring, and the batteries from a catastrophic short complete with fire somewhere short of the inverter.

Note also that if you put the fuses between the battery post and your wires or bus bars to which the CC and the inverter are both connected the inverter could see as much as the fuse current plus the maximum output current of your CC. The fuses not only are not there to protect the inverter, they will not necessarily even protect the inverter.



Some would recommend two sets of battery fuses, one for the inverter connection and one for the CC connection, but that can be pretty hard to achieve.

[hammick]

What size are the preterminated cables?

The reason that you should ignore Schneider's advice is that their sole concern is protecting the inverter.
The purpose of the fuses at the battery terminals is to protect you, the wiring, and the batteries from a catastrophic short complete with fire somewhere short of the inverter.

Note also that if you put the fuses between the battery post and your wires or bus bars to which the CC and the inverter are both connected the inverter could see as much as the fuse current plus the maximum output current of your CC. The fuses not only are not there to protect the inverter, they will not necessarily even protect the inverter.



Some would recommend two sets of battery fuses, one for the inverter connection and one for the CC connection, but that can be pretty hard to achieve.

My battery cables are 10' 4/0 The prewired DC cables in the Conext PDP (power distribution panel) are also 4/0

My charge controller will connect to 60a breakers inside the PDP. So the single set of battery cables will carry the charge current through the same fuses that the loads go through.

[Sunking]

I like your answer Sunking because I have four of the 150a Bussman fuses. I will use these. Obviously they are more than enough for charging. If I ever blow them with a load I'll go up to 175a or 200a.

Good choice and I highly doubt it will ever give you a nuisance trip. Looking at the Inverter specs full power is 97% efficient. So operating at 48 volts with 150 amps input is 7200 Watts input and a load of 7200 watts x .97 = 6984 watts load. I just cannot see you doing that for any period of time to operate the fuse.

One tip, wire the battery to Inverter for 250 amps.so in th eevent you do need to larger fuse th ewire can safely do it. Wire size is based on the fuze size. If the wire is limited to 150 amps, that is as large of a fuse as should use.

[QUOTE=hammick;n340834]BTW Blue Seas terminal fuses are made by Bussmann. [QUOTE=hammick;n340834]

Yep I knew that.