INSTALLATION
CABLE SIZING, TERMINATION AND FUSING
The size of the cables used to connect the power supply, the battery and the load
to this unit will depend upon the maximum value of the current flow and the
length of the cable run. Current flowing through a cable will produce an undesir-
able voltage drop along the length of the cable. The voltage drop is proportional
to the resistance of the cable. Higher resistance produces higher voltage drop.
The resistance of the cable increases as the cable becomes thinner. Similarly, the
resistance increases with the length of the cable. It is desirable to limit the
voltage drop to 2%.
Fuse in the battery circuit
A battery can supply very heavy current in case of short circuit in the path across
its terminals. This can cause overheating of the cables / connected device(s) and
consequent risk of melted insulation and possibility of fire. Hence, for safety, a
very fast acting fuse of appropriate current capacity should be connected in
series with the positive cable and should be placed as close as possible to the
positive terminal of the battery. Type “ANN” series fuses and Fuse Block No.
4164 made by Bussmann or similar are recommended.
The following Table gives the recommended sizes of cable and fuses:
Current
Cable length
Cable Length
Fuse
up to 3 ft
.
up to 6 ft
.
( Bussmann Type#
)
25 A
# 12 AWG
#8 AWG
35 A, Type ANN-35
10 A
# 14 AWG
#12 AWG
35 A, Type ANN-35
The terminals have a tubular hole of diameter 5 mm with set screw for connect-
ing the input and output cables. If the bare end of a multi-stranded cable is used
directly, the set screw may not pinch all the strands firmly and will result in a
loose connection which will cause voltage drop and excessive heating.
For a
firm connection, the cable ends should be terminated with suitable pin type
of terminal.
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