Samlex America PST-2000-24 - Manual (Page 31)

30 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 31
seCtIOn 8 | Installation
terminal of the inverter ► Battery (–) terminal) is completed, these capacitors
will start charging and the unit will momentarily draw very heavy current that
will produce sparking on the last contact in the input loop even when the oN/
off switch on the inverter is in the off position. Ensure that the external fuse is
inserted only after all the connections in the loop have been completed so that
the sparking is limited to the fuse area.
The flow of electric current in a conductor is opposed by the resistance of the conductor.
The resistance of the conductor is directly proportional to the length of the conductor
and inversely proportional to its cross-section (thickness). The resistance in the conduc-
tor produces undesirable effects of voltage drop and heating. Thus, thicker and shorter
conductors are desirable.
The size (thickness / cross-section) of the conductors is designated by AWG (American
Wire Gauge). Please note that a smaller AWG # denotes a thicker size of the conductor
up to AWG #1. Wires thicker than AWG #1 are designated AWG 1/0, AWG 2/0, AWG 3/0
and so on. In this case, increasing AWG # denotes thicker wire.
The DC input circuit is required to handle very large DC currents and hence, the size of
the wires and connectors should be selected to ensure minimum voltage drop between
the battery and the inverter. Thinner wires and loose connections will result in poor
inverter performance and will produce abnormal heating leading to risk of insulation
melt down and fire. Normally, the thickness of the wire should be such that the voltage
drop due to the current & the resistance of the length of the wire should be limited to
less than 5%. Use oil resistant, multi- stranded copper wire rated at 105ºC / 221ºf
minimum. Do not use aluminum wire as it has higher resistance per unit length.
Wires can be bought at a marine / welding supply store.
effects of low voltage on common electrical loads are given below:
- Lighting circuits - incandescent and Quartz Halogen: A 5% voltage drop causes an
approximate 10% loss in light output. This is because the bulb not only receives less
power, but the cooler filament drops from white-hot towards red-hot, emitting much
less visible light.
- Lighting circuits - Fluorescent: Voltage drop causes a nearly proportional drop in
light output.
- Ac induction motors: These are commonly found in power tools, appliances, well
pumps etc. They exhibit very high surge demands when starting. Significant voltage
drop in these circuits may cause failure to start and possible motor damage.
- PV battery charging circuits: These are critical because voltage drop can cause a dis-
proportionate loss of charge current to charge a battery. A voltage drop greater than
5% can reduce charge current to the battery by a much greater percentage.
Fuse Protection in Battery circuits
A battery is an unlimited source of current. Under short circuit conditions, a battery can
supply thousands of Amperes of current. If there is a short circuit along the length of