I am planning to install a Xantrax 1750 Inverter and the manual calls for a 250A Class T fuse. These fuses are quite expensive. Can I use a 250A breaker which is a LOT cheaper.
Thanks
Fred
Your breaking DC voltage I don't know if a AC breaker would work or not but we will find out 8)
Here is a cheaper alternative, an ANL fuse available on eBay:
https://m.ebay.com/itm/High-Quality-1-0-4-8-Gauge-ANL-Fuse-Holder-2-Pack-Gold-300-Amp-300A-Fuse-USA/232352201432?hash=item3619453ad8%3Ag%3APicAAOSwi7RZKyNB%3Asc%3AUSPSFirstClass%2186305%21US%21-1&_nkw=samurai+sanl1020&_from=R40&rt=nc
There was talk about where you installed the fuse too some say on the positive + side,Sean told me to install mine on the negative - which I done ,I still don't understand what difference it made
You want to use a fuse. They break faster, and if this fuse blows you've got bigger problems than having to replace the fuse. If you size the inverter for the intended load, the fuse should only blow on a catastrophic failure, like a short circuit.
Quote from: luvrbus on July 25, 2018, 12:53:37 PM
There was talk about where you installed the fuse too some say on the positive + side,Sean told me to install mine on the negative - which I done ,I still don't understand what difference it made
On my Trace, I installed it on the positive DC lead as per directions. But the last bus I worked on had it on the positive and negative sides. The negative side was blown. That is how I have the one in the picture-- I got the fuses and holder for the price of one fuse.
That is a another thing I don't understand is why they want a class T,the only difference I see between the T and the ANL the ANL has a element (link) that burns into and the class T has sand or glass I don't know which it melts breaking the circuit.
Class T fuses are very quick-blowing, so maybe that's why Xantrex wants them used. Magnum doesn't specify what type of fuse for their inverters, so I use a 250A ANL for my MS2000. ANLs are cheap (<$10 for five) compared to Class Ts that can be eye-wateringly expensive.
When Sean was recommending fuses on the negative side, he was talking about catastrophe fuses for entire battery banks, not individual load fuses. On his recommendation I have a 300A Class T for each of my house battery banks on their negative feed cables, but I'll also use Blue Sea battery terminal fuses for each pair of golfcart batteries on their positive feeds, plus individual fuses or CBs for each item or circuit. Can't be too safe!
John
So can you or not use a breaker in place of a Class T fuse inquiring minds here
Quote from: Fred Mc on July 25, 2018, 12:06:39 PM
I am planning to install a Xantrax 1750 Inverter and the manual calls for a 250A Class T fuse. These fuses are quite expensive. Can I use a 250A breaker which is a LOT cheaper.
Thanks
Fred
From what I've read, you cannot just swap the same size breaker for a fuse. They each have different characteristics in how they protect a circuit.
I see the Blue Sea 250A Class T fuse is listed at about $45. Where can you get a good quality 250A breaker for less? Seems to me that if the manual calls for a fuse, then I'd be using a fuse.
A "breaker" is for AC amps. A "fuse" nowadays is for DC amps. Many years ago they made AC fuses, but again they were designed for AC amps.
Quote from: Geoff on July 25, 2018, 05:07:14 PM
A "breaker" is for AC amps. A "fuse" nowadays is for DC amps. Many years ago they made AC fuses, but again they were designed for AC amps.
An amp is an amp.
Breakers are commonly used on DC circuits.
My big Trace 4024 came as a package with a 250 amp DC breaker box, also branded by Trace.
Happy coaching!
Buswarrior
Quote from: bobofthenorth on July 26, 2018, 02:53:57 PM
An amp is an amp.
Breakers are commonly used on DC circuits.
It's not the amps. It's not the volts. It's the arc. An AC circuit doesn't produce nearly as large of an arc when the circuit breaks due to the way the current alternates. A DC circuit produces a much larger arc when the circuit breaks, and this is what causes the damage to the contacts in the switch or breaker. The larger arc is why the same switch may have a 100-amp rating on AC and only a 10-amp rating on DC. The increased arc from the DC circuit can cause the contacts to pit, wear, or actually stick together. For a circuit breaker to function properly on a 250-amp DC circuit it would have to be much beefier than one designed for only an AC circuit.
Yes, and that's why one chooses a properly rated device for wherever it is going?
Boring work, reading the small print. Thank God for CSA, UL and friends...
Happy coaching!
Buswarrior
Quote from: Geoff on July 25, 2018, 12:37:54 PM
Here is a cheaper alternative, an ANL fuse available on eBay:
https://m.ebay.com/itm/High-Quality-1-0-4-8-Gauge-ANL-Fuse-Holder-2-Pack-Gold-300-Amp-300A-Fuse-USA/232352201432?hash=item3619453ad8%3Ag%3APicAAOSwi7RZKyNB%3Asc%3AUSPSFirstClass%2186305%21US%21-1&_nkw=samurai+sanl1020&_from=R40&rt=nc
AN ANL fuse is not a T class fuse. If your manual call out for a type fuse then that's the recommended type. Most likely do to it's disconnect characteristics when she blows. Other types will take longer to fully disconnect causing potential damage to equipment. FWIW
Jack
Additional considerations:
Power is what causes the fuse to blow. Wattage actually, against time. Fuses aren't rated for wattage but maybe they should be. They are not rated but are classified by time interval. So you have the wattage applied over the time period and the result is a power curve. Exceed the curve and the fuse melts. Also, AC power calculations require the use of an averaging factor or RMS number, usually about .7 to account for the sine wave.
Some fuses dissipate heat faster than others, roughly classified as slow blow fuses. The inverse is also correct. A FB fuse can replace a SB fuse if it is oversized by the correct fraction. The inverse is not really true.
Due to the RMS correction factor a breaker used for AC may not be rated correctly for DC.
Jim
Oh, all so technical! Does this mean I can't put a penny behind the screw in fuse at Grandma's house?
There are DC breakers designed for this kind of application. I think this one is designed for big solar installations and works in a Magnum inverter system setup. Interestingly it calls out a slow response time to minimize nuisance trips. I guess if Magnum has designed it for their inverters it's probably the right thing. https://www.solarwholesaler.ca/product/magnum-250amp-dc-breaker-front-mount-copy/
Quote from: bevans6 on July 28, 2018, 12:19:40 PM
There are DC breakers designed for this kind of application. I think this one is designed for big solar installations and works in a Magnum inverter system setup. Interestingly it calls out a slow response time to minimize nuisance trips. I guess if Magnum has designed it for their inverters it's probably the right thing. https://www.solarwholesaler.ca/product/magnum-250amp-dc-breaker-front-mount-copy/
that jewel makes a $45.00 class T fuse seem cheap 200 bucks for a breaker not on my watch
Like I said before, I put the T fuse for my Trace SW2512, it has never blown in 15 years. How do you blow an inverter fuse anyway? Realistically, your inverter would have to have a massive internal malfunction to blow the intake DC cable. A malfunction that would have to happen under warranty, otherwise it would be cheaper to buy a new inverter.
I thought the fuse was more for the battery end, which would be a short. The ANL fuse I replaced went between the house battery bank and the frame ground. Obviously it blew when the batteries were replaced and someone touched the leads wrong. The only other way the battery side of the fuse could blow if if you were T-boned by another vehicle directly into the battery pack.