The fitting of adequate fuses or circuit protection
in all DC circuits is essential. These must be big enough to carry the
maximum expected current, but not over-sized for the current rating of
wire used.
Suitably rated fuses of the types listed below should
be used between the battery and load or charge circuits, placed as close
as possible to the battery. Fuses need to be sized based upon the length
of time the maximum current will occur taking into account surge ability
of the inverter or other devices.
Currents need to be 10% to 20% lower than fuse
ratings to avoid nuisance fuse blowing.
Also inverter efficiency needs to be considered. eg.
if this is 85% at high load a 3 kW AC load would draw 3450 W from the DC
battery, (ie. 288 A @ 12 V; 144 A @ 24 V).
DC rated circuit breakers can also be used. These can then act as
safe and convenient disconnect switches if servicing is required.
Time vs.Amps Fuse Chart (for class T fuses)
FUSE BLOW POINT
(in Amps)
Time
200 Amp Fuse
300 Amp Fuse
400 Amp Fuse
1 second
670
1060
1450
6 seconds
530
800
1100
1 minute
370
580
800
4 minutes
340
520
710
8 minutes
310
500
690
16 minutes
300
475
650
32 minutes
275
435
600
1 hour
250
400
550
1 to 3 hours
200
300
400
Long Term Load Handling
3 hours or more
160
240
320
In-Line Fuses
In-line fuseholder with screw terminals (rated 10A).
Takes 1.25" glass fuses. Ideal for basic protection of small DC
circuits.
IL-FH
In-line 1.25" fuse holder
IL-F/5
5 A 1.25" fuse
IL-F/10
10 A 1.25" fuse
Carriers With Removable Fuses
These allow easy circuit isolation by pulling out the
fuse together with the protective lid of the fuse carrier.
NS-FH
NS fuse carrier
For 10-32 A fuses
NS-10
NS fuse
10 A
NS-16
NS fuse
16 A
NS-20
NS fuse
20 A
NS-25
NS fuse
25 A
NS-32
A3 fuse carrier
32 A
A3-FH
A3 fuse
For 32-63 A fuses
A3-63
A3 fuse
63 A
A3-63M100
A4 fuse carrier
63 A with 100 A surge
A4-FH
A4 fuse
For 80-100 A fuses
A4-80
A4 fuse
80 A
A4-100
A4 fuse
100 A
A4-100M160
A4 fuse
100 A with 160 A
surge
B2-FH
B2 fuse carrier
For 125-200 A fuses
B2-200M250
B2 fuse
200 A with 250 A
surge
NS-FH
A3-FH
TFB T-Block Inverter Fuses
Fuse blocks with bolt-on Class T fuses. Polycarbonate
covers.
FB200-T
Fuse
block & 200 A fuse
F200-T
Spare
200 A fuse
FB300-T
Fuse
block & 300 A fuse
F300-T
Spare
300 A fuse
OutBack DC Circuit Breakers
Ideal for use in OutBack FLEXware DC units but can
also be mounted in other enclosures to give DC protection and
disconnection.
Fuse blocks with bolt-on Class T fuses. Polycarbonate
covers.
Ideal for use in OutBack FLEXware DC units but can
also be mounted in other enclosures to give DC protection and
disconnection.