Samlex America SDC-12 - Manual

INSTRUCTION MANUAL
24 VDC TO 12VDC CONVERTER - MODEL NO. SDC-12 ITEM NO. 06035
SDC-12 is a 24 VDC (nominal) to 12 VDC (nominal) converter based on a high performance fixed frequency power switching regula-
tor. It is designed to deliver a maximum current of 12A at 13.8 VDC. In this converter, there is no isolation between the input and the
output sides. (Both the input & output have common negative ground.)
Features:
•
High efficiency switching regulator
•
Small size and light weight
•
Cycle by cycle current limiting
•
Over voltage , over heating, short circuit and reverse polarity protections
INSTALLATION AND OPERATION
General installation requirements
- Install the unit in a cool, dry, protected and well ventilated space
- The unit may be installed on top of a horizontal surface or on the bottom of a horizontal surface. The unit can be installed horizon-
tally on a vertical surface
Input and output connections
The unit has a terminal block with 4 male flat tabs (6.3 mm) for quick connection. One is for positive 24 VDC input (marked +24 V),
two are common negative for input and output (marked ground) and one is for positive 12 VDC output (marked +13.6 VDC).
CAUTION ! Please ensure that the polarity of the input connection is not reversed. Always connect the positive of the 24 V
battery to the positive terminal marked +24V and the negative terminal to any one of the two common negative terminals
marked 0 V. A reverse polarity connection will blow the fuse inside the unit
Sizing of input and output conductors. Conductors have resistance that opposes the current flow and produces voltage drop and
heating. The resistance is directly proportional to the length of the conductor and is inversely proportional to the thickness (area of
cross-section). Thus, a longer and thinner conductor will have higher resistance and will, therefore, produce higher voltage drop and
more heating. The size of a conductor for a particular application will depend upon the maximum current it is required to carry and over
what distance. The size of a conductor is designated by AWG (American Wire Gauge) number. The smaller the AWG number, the
thicker the conductor. The conductors should be sized for a maximum voltage drop of 2%. The cables should be multi-
stranded insulated copper cable rated for at least 90 º C and preferably oil resistant. The cables can be bought at a welding /
marine supply store.
Cables for 24 VDC input and 12 VDC output connections. The cables on the 24 VDC input side should be able to carry a maximum
current of approximately 9 A (for extreme conditions when delivering 12.5 A on the output at current limit at lowest 24 V input bat-
tery voltage of 20 V). To limit the voltage drop to 2%, use # 14 AWG for distance up to 6 ft. and # 12 AWG for up to 10 ft. The
cables on the 12 VDC output side should be able to carry the full current under current limit conditions. To limit the drop in
voltage to 2%, use # 14 AWG multi stranded cables to connect to the load for a distance of up to 6 ft. and # 12 AWG for a distance of
up to 10 ft. Use female quick connect terminals (tab size 6.3 mm) on the ends of the cables to enable connection to the male tabs
of the terminal block
External fuses on the input and output sides: The input and output connections should be made through suitable fast blow fuses
(For example “Bussmann” Type ATC or ATM automotive type fuses). The fuses should be connected in series with the positive
input and output cables. The 32V, 10A fuse on the 24 V input side should be as close to the battery positive terminal as possible. This
will prevent the possibility of overheating / melting of the input side cables in case of short circuit on the input side cabling (A battery
can provide very large currents during short circuit condition) Use a 32V, 15A fuse on the output side.
WARNING: The warranty will be voided if the above external fuses are not used