Samlexpower PST-30S-12A User manual

300 Watt
Pure Sine Wave
DC-AC Inverter
PST-30S-12A
PST-30S-24A
Owner's
Manual
Please read this
manual before
operating your
DC-AC inverter.

Safety Instructions............................................................................................. 2,3
Inverters - General Information .................................................................... 4,5,6
Characteristics of Sinusoidal AC Power............................................................... 7
Advantages of Sine Wave Inverters .................................................................... 8
AC Power Distribution and Grounding.................................................... 9,10,11
Limiting Electromagnetic Interference (EMI) ................................................... 11
Powering direct/embedded SMPS..................................................................... 12
Principle of Operation ....................................................................................... 13
Layout ................................................................................................................. 13
Specifying Batteries, Chargers and Alternators ........................... 14,15,16,17,18
Installation...................................................................................... 19,20,21,22,23
Operation ...................................................................................................... 24,25
Protection Against Abnormal Conditions.................................................... 25,26
Troubleshooting Guide ................................................................................. 27,28
Specications...................................................................................................... 29
Warranty............................................................................................................. 30
INDEX
Page 1

Page 2
SAFETY INSTRUCTIONS
Please read these instructions before installing or operating the inverter to prevent
personal injury or damage to the inverter.
GENERAL
Installation and wiring compliance
• Installation and wiring must comply with the local and national electrical codes
and must be done by a certied electrician
Preventing electrical shock
• Always connect the grounding connection on the inverter to the appropriate
grounding system
• Disassembly / repair should be carried out by qualied personnel only.
• Disconnect all AC and DC side connections before working on any circuits
associated with the inverter. Turning the on/off switch on the inverter to off
position may not entirely remove dangerous voltages
• Be careful when touching bare terminals of capacitors. The capacitors may retain
high lethal voltages even after the power has been removed. Discharge the
capacitors before working on the circuits
Installation environment
• The inverter should be installed indoor only in a well ventilated, cool, dry
environment
• Do not expose to moisture, rain, snow or liquids of any type.
• To reduce the risk of overheating and re, do not obstruct the suction and
discharge openings of the cooling fans
• To ensure proper ventilation, do not install in a low clearance compartment
Preventing re and explosion hazards
Working with the inverter may produce arcs or sparks. Thus, the inverter should not
be used in areas where there are inammable materials or gases requiring ignition
protected equipment. These areas may include spaces containing gasoline powered
machinery, fuel tanks, battery compartments
Precautions when working with batteries
• Batteries contain very corrosive diluted sulphuric acid as electrolyte. Precautions
should be taken to prevent contact with skin, eyes or clothing
• Batteries generate hydrogen and oxygen during charging resulting in evolution
of explosive gas mixture. Care should be taken to ventilate the battery area and
follow the battery manufacturer’s recommendations.
• Never smoke or allow a spark or ame near the batteries.
• Use caution to reduce the risk of dropping a metal tool on the battery. It could
spark or short circuit the battery or other electrical parts and could cause an
explosion.
• Remove metal items like rings, bracelets and watches when working with
batteries. The batteries can produce a short circuit current high enough to weld a
ring or the like to metal and thus cause a severe burn.
• If you need to remove a battery, always remove the ground terminal from the
battery rst. Make sure that all the accessories are off so that you do not cause a
spark

Page 3
INVERTER RELATED
Preventing paralleling of the AC output
The AC output of this inverter cannot be synchronised with another AC source and
hence, it is not suitable for paralleling. The AC output of the inverter should never be
connected directly to an electrical breaker panel / load center which is also fed from
the utility power / generator. Such a connection may result in parallel operation of the
different power sources and AC power from the utility / generator will be fed back
into the inverter which will instantly damage the output section of the inverter and
may also pose a re and safety hazard. If an electrical breaker panel / load center is
fed from an inverter and this panel is also required to be powered from additional
alternate AC sources, the AC power from all the AC sources like the utility / generator
/ inverter should rst be fed to a manual selector switch and the output of the selector
switch should be connected to the electrical breaker panel / load center.
To prevent possibility of paralleling and severe damage to the inverter, never use a
simple jumper cable with a male plug on both ends to connect the AC output of the
inverter to a handy wall receptacle in the home / RV.
Connecting to multi-wire branch circuits
Do not directly connect the hot side of the inverter to the two hot legs of the 120 /
240 VAC electrical breaker panel / load centre where multi-wire ( common neutral )
branch circuit wiring method is used for distribution of AC power. This may lead to
overloading / overheating of the neutral conductor and is a risk of re.
A split phase transformer ( isolated or auto-transformer ) of suitable wattage rating
( 25 % more than the wattage rating of the inverter ) with primary of 120 VAC and
secondary of 120 / 240 VAC ( Two 120 VAC split phases 180 degrees apart) should be
used. The hot and neutral of the 120 VAC output of the inverter should be fed to
the primary of this transformer and the 2 hot outputs ( 120 VAC split phases ) and the
neutral from the secondary of this transformer should be connected to the electrical
breaker panel / load centre.
Preventing input over voltage
It is to be ensured that the input voltage of the inverter does not exceed 16.5 VDC
(PST-30S-12A) or 33 VDC (PST-30S-24A) to prevent permanent damage to the inverter.
Please observe the following precautions:
• Ensure that the maximum charging voltage of the battery charger / alternator /
solar charge controller is below 16.5 VDC (PST-30S-12A) or 33 VDC (PST-30S-24A)
• Do not use unregulated solar panels to charge a battery. Under cold ambient
temperatures, the output of the solar panel may exceed 18 VDC for 12V battery
system of 36VDC for 24V battery system. Always use a charge controller between
the solar panel and the battery.
• Do not connect the inverter to a battery that has a voltage higher than the rated
battery input voltage of the inverter.
Preventing reverse polarity on the input side
When making battery connection on the input side, make sure that the polarity of
battery connection is correct (Ensure that the centre contact of the cigarette lighter
receptacle is connected to the positive of the battery. The centre pin (tip) of the
cigarette lighter plug attached to the inverter is positive). If the input is connected in
reverse polarity, DC fuse inside the inverter will blow and may also cause permanent
damage to the inverter.

INVERTERS - GENERAL INFORMATION
Why an inverter is needed
The utility grid supplies you with alternating current (AC) electricity. AC is the standard
form of electricity for anything that “plugs in” to the utility power. Direct current (DC)
electricity ows in a single direction. Batteries provide DC electricity. AC alternates its
direction many times per second. AC is used for grid service because it is more practical
for long distance transmission. For more details read “Characteristics of Sinusoidal AC
Power” on page 7.
An inverter converts DC to AC, and also changes the voltage. In other words, it is a
power adapter. It allows a battery-based system to run conventional AC appliances
directly or through conventional home wiring. There are ways to use DC directly, but
for a modern lifestyle, you will need an inverter for the vast majority, if not all of your
loads (in electrical terms, “loads” are devices that use electrical energy).
Incidentally, there is another type of inverter called grid-interactive. It is used to feed
solar (or other renewable) energy into a grid-connected home and to feed excess
energy back into the utility grid. This inverter is NOT grid interactive
Inverter should meet the application
To choose an inverter; you should rst dene your needs. Where is the inverter to be
used? Inverters are available for use in buildings (including homes), for recreational
vehicles, boats, and portable applications. Will it be connected to the utility grid in
some way? Electrical conventions and safety standards differ for various applications,
so don’t improvise.
Electrical Standards
The DC input voltage must conform to that of the electrical system and battery bank.
12 volts is recommended for small, simple systems. 24 and 48 volts are the common
standards for higher capacities. A higher voltage system carries less current, which
makes the system wiring cheaper and easier.
The inverter’s AC output must conform to the conventional power in the region in
order to run locally available appliances. The standard for AC utility service in North
America is 120 and 240 Volts at a frequency of 60 Hertz (cycles per second). In Europe,
South America, and most other places, it is 230 volts at 50 Hertz.
Power capacity – “Continuous” and “Surge”
How much load can an inverter handle? Its power output is rated in Watts. Read
details under “Characteristics of Sinusoidal AC Power” on page 7. There are two
levels of power rating -a continuous rating and a surge rating. Continuous means the
amount of power the inverter can handle for an indenite period of hours. When
an inverter is rated at a certain number of Watts, that number generally refers to its
continuous rating. The “surge power” indicates the power to handle instantaneous
overload of a few seconds to provide the higher power required to start certain type
of devices and appliances.
Page 4

Page 5
Loads that require “surge power” to start
Resistive types of loads (like incandescent lamps, toaster, coffee maker, electric range,
iron etc) do not require extra power to start. Their starting power is the same as their
running power.
Some loads like induction motors and high inertia motor driven devices will initially
require a very large starting or “surge” power to start from rest. Once they have
started moving and have attained their rated speed, their power requirement reduces
to their normal running power. The surge may last up to 5 seconds.
TVs and microwave ovens also require surge power for starting. The manufacturers’
specication of the appliances and devices indicates only the running power required.
The surge power required has to be guessed at best. See below under “Sizing of
inverter for loads that require starting surge”.
If an inverter cannot efciently feed the surge power, it may simply shut down instead
of starting the device. If the inverter’s surge capacity is marginal, its output voltage
will dip during the surge. This can cause a dimming of the lights in the house, and will
sometimes crash a computer.
Any weakness in the battery and cabling to the inverter will further limit its ability to
start a motor. A battery bank that is undersized, in poor condition, or has corroded
connections, can be a weak link in the power chain. The inverter cables and the
battery interconnect cables must be sized properly. The spike of DC current through
these cables is many hundreds of amps at the instant of motor starting. Please follow
the instructions under "Installation - DC side connections" on pages 20 & 21.
Sizing of inverter for loads that require starting surge
Observe the following guideline to determine the continuous wattage of the inverter
for powering loads that require starting surge. (Multiply the running watts of the
device/appliance by the Surge Factor)
*NOTE: The surge power rating specied for this inverter is valid for duration
of less than 1 second. This very short duration may not be sufcient to
start motor based loads which may require up to 5 seconds to complete
starting process. Hence, for purposes of sizing the inverter, use only the
continuous power rating of this inverter.
Type of Device or Appliance Surge Factor for Determining the Continuous x Wattage of the Inverter
(No. of times the running power rating of the device/appliance)
Refrigerator / Freezer 5
Air Compressors 4
Dishwasher 3
Automatic Washer 3
Sump pump 3
Furnace fans 3
Industrial motors 3
Portable kerosene / diesel fuel heater 2
Circular saw 3
Bench Grinder 3

Page 6
Power rating of Microwaves
The power rating of the microwave generally refers to the cooking power. The
electrical power consumed by the microwave will be approximately 2 times the
cooking power. The “surge power” of the inverter should be 2 times the electrical
power (i.e., 4 times the cooking power). Please note that the surge power of the
microwave is not as long as the motor load and hence, the surge power of the inverter
can be considered to determine adequacy of meeting the starting surge power
Powering a water supply pump
A water well or pressure pump often places the greatest demand on the inverter.
It warrants special consideration. Most pumps draw a very high surge of current
during start up. The inverter must have sufcient surge capacity to handle it while
running any other loads that may be on. It is important to size an inverter sufciently,
especially to handle the starting surge (If the exact starting rating is not available,
the starting surge can be taken as 3 times the normal running rating of the pump).
Oversize it still further if you want it to start the pump without causing lights to dim
or blink.
In North America, most pumps (especially submersibles) run on 240 VAC, while smaller
appliances and lights use 120 VAC. To obtain 240 VAC from a 120 VAC inverter, use a
120 VAC to 240 VAC transformer. If you do not already have a pump installed, you can
get a 120 volt pump if you don’t need more than 1/2 HP.
Idle power
Idle power is the consumption of the inverter when it is on, but no loads are running.
It is “wasted” power, so if you expect the inverter to be on for many hours during
which there is very little load (as in most residential situations), you want this to be as
low as possible.
Phantom and idling loads
Most of the modern gadgets draw some power whenever they are plugged in. Some
of them use power to do nothing at all. An example is a TV with a remote control. Its
electric eye system is on day and night, watching for your signal to turn the screen on.
Every appliance with an external wall-plug transformer uses power even when the
appliance is turned off. These little loads are called “phantom loads” because their
power draw is unexpected, unseen, and easily forgotten.
A similar concern is “idling loads.” These are devices that must be on all the time in
order to function when needed. These include smoke detectors, alarm systems, motion
detector lights, fax machines, and answering machines. Central heating systems
have a transformer in their thermostat circuit that stays on all the time. Cordless
(rechargeable) appliances draw power even after their batteries reach a full charge. If
in doubt, feel the device. If it’s warm, that indicates wasted energy.

Page 7
CHARACTERISTICS OF SINUSOIDAL AC POWER
Voltage, current, power factor, types of loads
The voltage waveform of 120 VAC, 60 Hz mains / utility power is like a sine wave. In
a voltage with a sine wave-form, the instantaneous value and polarity of the voltage
varies with respect to time and the wave-form is like a sine wave. In one cycle, it
slowly rises in the positive direction from 0 V to a peak positive value + Vpeak = 170
V, slowly drops to 0 V, changes the polarity to negative direction and slowly increases
in the negative direction to a peak negative value - Vpeak =170 V and then slowly
drops back to 0 V. There are 60 such cycles in 1 sec. Cycles per second is called the
“frequency” and is also termed “Hertz (Hz.). If a linear load is connected to this type
of voltage, the load will draw current which will also have the same sine wave-form.
However, the peak value of the current will depend upon the impedance of the load.
Also, the phase of the sine wave-form of the current drawn by the linear load may
be the same or lead / lag the phase of sine wave-form of the voltage. This phase
difference determines the “Power Factor (mathematically = the cosine of the phase
difference)” of the load. In a resistive type of load (like incandescent lamps, heaters
etc) the sine wave-form of the current drawn by the load has 0 phase difference
with the sine wave-form of the voltage of the AC power source. The Power Factor
of a resistive load is unity (1). The rated output power (in Watts) of the inverters is
normally specied for resistive type of loads that have unity (1) Power Factor. In a
reactive type of load (like electric motor driven loads, uorescent lights, computers,
audio / video equipment etc), the phase of the sine wave-form of the current drawn
by the load may lead or lag the sine wave-form of the AC voltage source. In this case,
the power factor of reactive loads is lower than unity (1) – generally between 0.8 and
0.6. A reactive load reduces the effective wattage that can be delivered by an AC
power source.
RMS and peak values
As explained above, in a sine wave, the instantaneous values of AC voltage (Volt, V)
and current (Ampere, A) vary with time. Two values are commonly used – Root Mean
Square (RMS) value and peak value. For simplicity, RMS value can be considered as an
average value. Mathematically, Peak Value = 1.414 x RMS value. For example, the 120
VAC, 60 Hz. mains / utility power is the RMS value. The peak value corresponding to
this is = 1.414 x 120 = 170V.
The values of the rated output voltage and current of an AC power source are their
RMS values
AC power – Watts / VA
The power rating of an AC power source is designated in Volt Amperes (VA) or in
Watts (W)
Power in Volt Amperes (VA) = RMS Volts (V) x RMS Amps (A)
Power in Watts = RMS Volts (V) x RMS Amps (A) x Power Factor
NOTE : The rated power of the inverter in Watts (W) is normally designated for a
linear, resistive type of load that draws linear current at unity (1) power
factor. If the load is linear and reactive type, the rated power of the inverter
in watts will be limited to its normal rated power in watts (W) x Power
Factor. For example, an inverter rated for 1000 W ( at unity power factor)
will be able to deliver only 600 watts to a reactive type of load with a
power factor of 0.6.

Page 8
ADVANTAGES OF A PURE SINE-WAVE INVERTER OVER A
MODIFIED SINE-WAVE INVERTER
The output voltage of a sine-wave inverter has a sine wave-form like the sine wave-
form of the mains / utility voltage. In a sine wave, the voltage rises and falls smoothly
with a smoothly changing phase angle and also changes its polarity instantly when
it crosses 0 Volts. In a modied sine wave, the voltage rises and falls abruptly, the
phase angle also changes abruptly and it sits at 0 Volts for some time before changing
its polarity. Thus, any device that uses a control circuitry that senses the phase (for
voltage / speed control) or instantaneous zero voltage crossing (for timing control)
will not work properly from a voltage that has a modied sine wave-form.
Also, as the modied sine wave is a form of square wave, it is comprised of multiple
sine waves of odd harmonics (multiples) of the fundamental frequency of the
modied sine wave. For example, a 60 Hz modied sine wave will consist of sine
waves with odd harmonic frequencies of 3rd (180 Hz), 5th (300 Hz.), 7th (420 Hz.)
and so on. The high frequency harmonic content in a modied sine wave produces
enhanced radio interference, higher heating effect in motors / microwaves and
produces overloading due to lowering of the impedance of low frequency lter
capacitors / power factor improvement capacitors.
Advantages of sine-wave inverters:
• Theoutputwave-formisasine-wavewithverylowharmonicdistortionand
clean power like utility supplied electricity
• Inductiveloadslikemicrowavesandmotorsrunfaster,quieterandcooler
• Reducesaudibleandelectricalnoiseinfans,uorescentlights,audio
ampliers, TV, fax and answering machines
• Preventscrashesincomputers,weirdprintoutsandglitchesinmonitors
Some examples of devices that may not work properly with modied sine wave and
may also get damaged are given below:
• Laserprinters,photocopiers,magneto-opticalharddrives
• Thebuilt-inclocksindevicessuchasclockradios,alarmclocks,coffee
makers, bread-makers, VCR, microwave ovens etc may not keep time
correctly
• Outputvoltagecontroldeviceslikedimmers,ceilingfan/motorspeed
control may not work properly (dimming / speed control may not function)
• Sewingmachineswithspeed/microprocessorcontrol
• Transformer-lesscapacitiveinputpowereddeviceslike(i)Razors,ashlights,
night-lights, smoke detectors etc (ii) Re-chargers for battery packs used
in hand power tools. These may get damaged. Please check with the
manufacturer of these types of devices for suitability
• DevicesthatuseradiofrequencysignalscarriedbytheACdistributionwiring
• Somenewfurnaceswithmicroprocessorcontrol/Oilburnerprimarycontrols
• Highintensitydischarge(HID)lampslikeMetalHalidelamps.These may get
damaged. Please check with the manufacturer of these types of devices for
suitability
• Someuorescentlamps/lightxturesthathavepowerfactorcorrection
capacitors. The inverter may shut down indicating overload

Page 9
AC POWER DISTRIBUTION AND GROUNDING
CAUTION! PLEASE NOTE THAT THE AC OUTPUT CONNECTIONS AND THE DC INPUT
CONNECTIONS ON THESE INVERTERS ARE NOT CONNECTED (BONDED)
TO THE METAL CHASSIS OF THE INVERTER. BOTH THE INPUT AND
OUTPUT CONNECTIONS ARE ISOLATED FROM THE METAL CHASSIS AND
FROM EACH OTHER. SYSTEM GROUNDING, AS REQUIRED BY NATIONAL/
LOCAL ELECTRICAL CODES / STANDARDS, IS THE RESPONSIBILITY OF THE
USER / SYSTEM INSTALLER.
Conductors for electrical power distribution
For single phase transmission of AC power or DC power, two conductors are required
that will be carrying the current. These are called the “current-carrying” conductors.
A third conductor is used for grounding to prevent the build up of voltages that may
result in undue hazards to the connected equipment or persons. This is called the “non
current-carrying” conductor (will carry current only under ground fault conditions)
Grounding terminology
The term “grounded” indicates that one or more parts of the electrical system are
connected to earth, which is considered to have zero voltage or potential. In some
areas, the term “earthing” is used instead of grounding.
A “grounded conductor” is a “current-carrying” conductor that normally carries
current and is also connected to earth. Examples are the “neutral” conductor in AC
wiring and the negative conductor in many DC systems. A “grounded system” is a
system in which one of the current-carrying conductors is grounded
An “equipment grounding conductor” is a conductor that does not normally carry
current (except under fault conditions) and is also connected to earth. It is used to
connect the exposed metal surfaces of electrical equipment together and then to
ground. Examples are the bare copper conductor in non-metallic sheathed cable
(Romex®) and the green, insulated conductor in power cords in portable equipment.
These equipment-grounding conductors help to prevent electric shock and allow
over-current devices to operate properly when ground faults occur. The size of this
conductor should be coordinated with the size of the over-current devices involved
A “grounding electrode” is the metallic device that is used to make actual contact
with the earth. Other types of grounding electrodes include metal water pipes and
metal building frames.
A “grounding electrode conductor” is the conductor between a common single
grounding point in the system and the grounding electrode
“Bond” refers to the connection between the “grounded conductor”, the “equipment
grounding” conductors and the “grounding electrode” conductor. Bonding is also
used to describe connecting all of the exposed metal surfaces together to complete
the equipment-grounding conductors.

Page 10
Grounded Electrical Power Distribution System
The National Electrical Code (NEC) requires the use of a “grounded electrical
distribution system”. As per this system, one of the two current-carrying conductors
is required to be grounded. This grounded conductor is called the “Neutral / Cold /
Return”. As this conductor is bonded to earth ground, it will be at near zero voltage
or potential. There is no risk of electrical shock if this conductor is touched. The
other current carrying conductor is called the “Line / Live / Hot”. The connection
between the “Neutral” and the grounding electrode conductor is made only at one
point in the system. This is known as the system ground. This single point connection
(bond) is usually made in the service entrance or the load center. If this connection is
inadvertently made in more than one place, then unwanted currents will ow in the
equipment grounding conductors. These unwanted currents may cause inverters and
charge controllers to be unreliable and may interfere with the operation of ground-
fault detectors and over-current devices.
NOTE: A current-carrying conductor that is not bonded to the earth ground cannot be
called a “neutral”. This conductor will be at an elevated voltage with respect to the
earth ground and may produce electrical shock when touched.
Polarity and color codes for power cords and plugs for AC devices and appliances
Single phase 120 VAC, 60 Hz AC devices and appliances use 2 pole, 3 wire grounding
conguration for connection to the AC power source. The plug of the power cord has
three pins – two at pins ( also called poles ) that are connected to the two current-
carrying conductors and a round pin which is connected to a non-current carrying
conductor ( this will carry current only during ground fault conditions ) . One at pin
is connected to a black current-carrying conductor which is also called “Line/Live/Hot”
pole. The other at pin is connected to the white current-carrying conductor also
called the “Neutral / Return / Cold” pole. The third round pin is connected to the non-
current carrying green “equipment grounding conductor”. This green “equipment
grounding conductor” is bonded to the metal chassis of the device or appliance.
AC output connections
The 120 VAC, 60 Hz version of the inverter uses NEMA 5-15R receptacles for
connecting the AC output of the inverter to devices and appliances tted with a
NEMA 5-15P plug. The two rectangular slots are connected to the current-carrying
conductors of the AC power source inside the inverter. The round slot is the
“equipment grounding” connection and is internally connected to the metal chassis of
the inverter.
CAUTION! : For the 120 VAC, 60 Hz NEMA 5-15R receptacle used in this inverter, the
current carrying conductor connected to the longer rectangular slot is isolated from
the metal chassis of the inverter. Hence, when the metal chassis of the inverter is
connected to the earth ground, the longer rectangular slot is not grounded to the
earth ground. The longer rectangular slot is, therefore, not a “neutral”. Do not touch
this slot as it will be at an elevated voltage with respect to the metal chassis / earth
ground and may produce an electrical shock when touched.

Page 11
Grounding to earth or to other designated ground
For safety, the metal chassis of the inverter is required to be grounded to the earth
ground or to the other designated ground (For example, in a mobile RV, the metal
frame of the RV is normally designated as the negative DC ground). An equipment
grounding bolt with a wing nut has been provided for grounding the metal chassis of
the inverter to the appropriate ground.
When using the inverter in a building, connect a # 8 AWG insulated stranded copper
wire from the above equipment grounding bolt to the earth ground connection (
a connection that connects to the ground rod or to the water pipe or to another
connection that is solidly bonded to the earth ground ). The connections must be
tight against bare metal. Use star washers to penetrate paint and corrosion.
When using the inverter in a mobile RV, connect a # 8 AWG insulated stranded copper
wire from the above equipment grounding bolt to the appropriate ground bus of the
RV (usually the vehicle chassis or a dedicated DC ground bus ). The connections must
be tight against bare metal. Use star washers to penetrate paint and corrosion.
The inverter contains internal switching devices which generate conducted and
radiated electromagnetic interference (EMI).
The magnitude of EMI is limited to acceptable levels by circuit design but can not be
entirely eliminated. The effects of EMI will also depend upon a number of factors
external to the power supply like proximity of the inverter to the EMI receptors, types
and quality of connecting wires and cables etc. EMI due to factors external to the
inverter can be reduced as follows:
• Ensure that the inverter is rmly grounded to the ground system of the building
or the vehicle
• Locate the inverter as far away from the EMI receptors like radio, audio and
video devices as possible
• Keep the DC side cables between the battery and the inverter as short as possible
• Twist the DC side cables. This will partially cancel out the radiated noise from the
cables
• Shield the DC side cables with metal sheathing / copper foil / braiding
• Use co-axial shielded cable for all antenna inputs (instead of 300 ohm twin leads)
• Use high quality shielded cables to attach audio and video devices to one another
• Do not operate other high power loads when operating audio / video equipment
LIMITING ELECTRO-MAGNETIC INTERFERENCE (EMI)

Page 12
POWERING DIRECT / EMBEDDED SWITCHED MODE
POWER SUPPLY (SMPS)
Non-linear nature of current drawn by Switched Mode Power Supplies
Power supplies are used to convert AC voltages like 120 VAC to various DC voltages
like 3.3 V, 5 V, 12 V, 24 V, 48 V etc. Majority of modern day electronic devices use
embedded general purpose Switch Mode type of Power Supplies (SMPS) to drive the
electronic circuitry. General purpose Switch Mode Power Supplies (SMPS) ( excepting
those that have power factor correction ) have one major disadvantage – the current
drawn by them from the AC power source has a non linear waveform ( the waveform
is not sinusoidal as the input voltage waveform but is in the form of short, larger
value pulses around the area of + Vpeak and -Vpeak ). This is due to the charging of
the input lter capacitor(s) mostly around the positive and negative peak portions of
the sinusoidal input voltage. The degree of non-linearity is measured by the "Crest
Factor":
Crest Factor = Peak Current / RMS Current
In a linear load, the Crest Factor is 1.414. However, in a general purpose SMPS, due to
its non linear nature, this factor will be much higher - in the region of up to 4. This will
mean that for a particular rated RMS current (applicable for a linear load), the general
purpose SMPS will draw much larger peak currents – approx. up to 4 times more than
its rated RMS current.
Inverters are protected against over current ( also called overloading ) by either
clipping the peaks of the output voltage ( this will result in a sine wave becoming
a square wave, reduction in the RMS value of the output voltage and generation
of harmonics and electrical noise ) or by shutting down the output voltage of the
inverter completely. Thus, if an inverter / generator is used to power a general
purpose SMPS, it will be forced to deliver higher peak currents resulting in premature
triggering of the inverter’s / generator's over current protection circuits. Thus, for safe
operation, the continuous RMS current rating of the inverter / generator should be at
least 2.8 times the continuous RMS current rating of the general purpose SMPS it is
required to power:
Peak current of inverter = Peak current of SMPS
or
RMS current of inverter X 1.414 = RMS current of SMPS X 4
or
RMS current of inverter = 4/1.414 X RMS current of SMPS
or
RMS current of inverter = 2.8 X RMS current of SMPS)
Alternatively, the continuous power rating of the inverter / generator in Watts / VA
should be at least 2.8 times the continuous power rating of the SMPS in Watts / VA

Page 13
LAYOUT
PRINCIPLE OF OPERATION
The inverter converts the DC voltage of the battery to 120 V, 60 Hz. AC voltage.
The voltage conversion takes place in two stages. In the rst stage, the DC voltage
of the battery is converted to a high voltage DC using high frequency switching and
Pulse Width Modulation (PWM) technique. In the second stage, the high voltage DC
is converted to 120 V, 60 Hz. sine-wave AC again using PWM technique. This is done
by using a special wave shaping technique where the high voltage DC is switched at
a high frequency and the pulse width of this switching is modulated with respect to a
reference sine-wave.
1 2 3
1. 120V AC output receptacle
2. L.E.D. indicator
3. On/Off Switch
4. Input terminals (back of unit -not shown)
RED - Positive (+)
BLACK - Negative (-)
5. Cooling fan (back of the unit - not shown)
6. Grounding lug (back of the unit - not shown)
Accessories Included
3' battery cable with battery clips, 3' battery cable with cigar plug
CAUTION!
Reverse polarity of input connection will blow the fuse inside the inverter and
may cause permanent damage. Ensure that the cigar lighter socket used for pow-
ering the inverter has the correct polarity with respect to the cigar lighter plug's,
positive (+) & negative (-) contact points. The contact at the tip of the cigar lighter
plug is positive (+) and the two spring loaded bow type contacts on the sides are
negative (-). Damage due to reverse polarity is not covered by warranty.

SPECIFYING BATTERIES, CHARGERS
& ALTERNATORS
The inverter will require Deep Cycle Lead Acid Batteries of appropriate capacity.
Lead-acid batteries can be categorized by the type of application: automotive service -
Starting/Lighting/Ignition (SLI, a.k.a. cranking) and deep cycle service
SLI Batteries
Everybody is familiar with the SLI batteries that are used for automotive starting and
powering vehicular accessories. SLI batteries are designed to produce high power
in short bursts but must be constantly recharged (normally with an alternator while
driving). Vehicle starting typically discharges 1%-3% of a healthy SLI battery’s capacity.
The automotive SLI battery is not designed for repeated deep discharge where up to
80 % of the battery capacity is discharged and then recharged. If an SLI battery is used
for this type of application, its useful service life will be drastically reduced
Deep Cycle Batteries
Deep cycle batteries are designed with thick-plate electrodes to serve as primary
power sources, to have a constant discharge rate, to have the capability to be deeply
discharged up to 80 % capacity and to repeatedly accept recharging. They are
marketed for use in recreation vehicles (RV), boats and electric golf carts – so they may
be referred to as RV batteries, marine batteries or golf cart batteries. There are two
categories of deep cycle lead acid batteries – wet and sealed. A wet cell battery has a
high tolerance to overcharging. However, it will release hydrogen gas when charging
that must be properly vented and the water level must be checked frequently. Sealed
batteries can either be Gel Cell or AGM (Absorbed Glass Mat). Both the Gel Cell and
AGM are maintenance free, have no liquid to spill and gassing is minimal. The Gel Cell
is the least affected by temperature extremes, storage at low state of charge and has
a low rate of self discharge. An AGM battery will handle overcharging slightly better
than the Gel Cell
Units of Battery capacity
The battery capacity is the measure of the energy the battery can store and deliver
to a load. It is determined by how much current any given battery can deliver over
a stipulated period of time. The energy rating is expressed in Ampere Hours (AH).
As a bench mark, the battery industry rates batteries at 20 hour rate i.e. how many
Amperes of current the battery can deliver for 20 hours at 80 º F till the voltage
drops to 10.5 Volts for 12 V battery and 21 V for 24 V battery. For example, a 100
AH battery will deliver 5 Amperes for 20 hours. Battery capacity is also expressed as
Reserve Capacity (RC) in minutes. Reserve capacity is the time in minutes for which the
battery can deliver 25 Amperes at 80 º F till the voltage drops to 10.5 Volts for 12 V
battery and 21 V for 24 V battery. Approximate relationship between the two units is
as follows:
Capacity in AH = Reserve Capacity in RC minutes x 0.6
Page 14

Typical battery sizes
Below is a chart of some battery sizes applicable for powering inverters:
BCI * Group Battery Voltage, V Battery AH
27 / 31 12 105
4 D 12 160
8D 12 225
GC2** 6 220
* Battery Council International
** Golf Cart
Reduction in usable capacity at higher discharge rates.
As stated above, the rated capacity of the battery in AH is applicable at a discharge
rate of 20 Hours. As the discharge rate is increased, the usable capacity reduces due
to “Peukert Effect”. This relationship is not linear but is more or less according to the
table below:
Table 1 Battery Capacity versus Rate of Discharge
Hours of Discharge Usable Capacity
20 100%
10 87%
8 83%
6 75%
5 70%
3 60%
2 50%
1 40%
Using the above table will show that a 100 AH capacity battery will deliver 100% (i.e.
full 100 AH) capacity if it is slowly discharged over 20 hours at the rate of 5 Amperes.
However, if it is discharged at a rate of 50 Amperes then theoretically, it should
provide 100 AH ÷ 50 = 2 hours. However, the Table above shows that for 2 hours
discharge rate, the capacity is reduced to 50% i.e. 50 AH. Therefore, at 50 Ampere
discharge rate the battery will actually last for 50 AH÷50 Amperes = 1 Hour
Page 15

Depth of discharge and battery life
The more deeply a battery is discharged on each cycle, the shorter the battery life.
Using more batteries than the minimum required will result in longer life for the
battery bank. A typical cycle life chart is given at Table 2 below:
TABLE 2. – TYPICAL CYCLE LIFE CHART
Depth of Discharge Cycle LifeCycle LifeCycle Life
% of AH Capacity Group 27 / 31 Group 8DGroup GC2
10 1000 1500 3800
50 320 480 1100
80 200 300 675
100 150 225 550
It is recommended that the depth of discharge should be limited to 50 %
Loss of battery capacity at low temperatures
Batteries lose capacity in low temperatures. At 32 º F, a battery will deliver about 70 to
80 % of its rated capacity at 80 º F. If the air temperature near the battery bank is
lower than 80 º F, additional batteries will be needed to provide the same usable
capacity. For very cold climates, an insulated / heated battery compartment is
recommended.
Series and parallel connection of batteries
When two or more batteries are connected in series, their voltages add up but their
AH capacity remains the same. For example, when two 12 V, 105 AH batteries are
connected in series, it becomes a 24 V, 105 AH battery. (Positive of the rst battery
is the positive terminal of the series connection. The negative of the rst battery is
connected to the positive of the second battery. The negative of the second battery is
the negative of the series connection)
When two or more batteries are connected in parallel, their voltages remain the
same but their capacities add up. For example, if two 12 V, 105 AH batteries are
connected in parallel, their voltage remains 12 V but their capacity becomes 105 × 2
= 210 AH (Connect the positive terminal of the rst battery to the positive terminal
of the second battery. These paralleled common positive terminals become the
positive terminal of the parallel combination. Connect the negative terminal of the
rst battery to the negative terminal of the second battery. These paralleled common
negative terminals becomes the negative terminal of the parallel combination)
Page 16

Sizing the Inverter Battery Bank
One of the most frequently asked question is, “how long will the batteries last?’. This
question cannot be answered without knowing the size of the battery system and the
load on the inverter. Usually this question is turned around to ask “How long do you
want your load to run?”, and then specic calculation can be done to determine the
proper battery bank size.
There are a few basic formulas and estimation rules that are used:
Formula 1 Power in Watts (W) = Voltage in Volts (V) x Current in Amperes (A)
Formula 2 For an inverter running from a 12 V battery system, the DC current
required from the 12 V batteries is the AC power delivered by the
inverter to the load in Watts (W) divided by 10
For an inverter running from a 24 V battery system, the D.C.
current required from the 24 V battery is equal to the A.C. power
delivered by the inverter to the load in Watts (W) divided by 20
Formula 3 Energy required from the battery = DC current to be delivered (A) x
time in Hours (H)
The rst step is to estimate the total AC watts (W) of load(s) and for how long the
load(s) will operate in hours (H). The AC watts are normally indicated in the electrical
nameplate for each appliance or equipment. In case AC watts (W) are not indicated,
formula 1 given above may be used to calculate the AC watts by multiplying 120 VAC
by the AC current in Amperes . The next step is to derive the DC current in Amperes
(A) from the AC watts as per formulae 2 above. An example of this calculation for 12
V inverter is given below.
Let us say that the total AC Watts delivered by the inverter = 1000 W
Then, using formula 2 above, the DC current to be delivered by the 12 V batteries =
1000 W ÷10 = 100 Amperes
Next, the energy required by the load in Ampere Hours (AH) is determined. For
example, if the load is to operate for 3 hours then as per Formula 3 above:
Energy to be delivered by the 12 V batteries = 100 Amperes × 3 Hours = 300 Ampere
Hours (AH)
Now, the capacity of the batteries is determined based on the run time and the usable
capacity. From Table 1 above, the usable capacity at 3 Hour discharge rate is 60%.
Hence, the actual capacity of the 12 V batteries to deliver 300 AH will be equal to 300
AH ÷ 0.6 = 500 AH
And nally, the actual desired rated capacity of the batteries is determined based on
the fact that normally only 80% of the capacity will be available with respect to the
rated capacity due to non availability of ideal and optimum operating and charging
conditions. So the nal requirements will be equal to:
500 AH ÷0.8 = 625 AH (note that the actual energy required by the load was 300 AH)
It will be seen from the above that the nal rated capacity of the batteries is almost 2
times the energy required by the load in AH.
Page 17

Thus, as a thumb rule, the AH capacity of the batteries should be twice the energy
required by the load in AH
For the above example, the 12 V batteries may be selected as follows:
- Use 6 Group 27/31, 12 V, 105 AH batteries in parallel to make up 630 AH, or
- Use 3 Group 8D, 12 V, 225 AH batteries in parallel to make up 675 AH
Charging Batteries
The batteries can be charged by using good quality AC powered battery charger or
from alternative energy sources like solar panels, wind or hydro systems. Make sure
an appropriate battery charge controller is used. It is recommended that the batteries
may be charged at 10% to 13 % of the Ampere Hour capacity (20 hour discharge
rate). Also, for complete charging (return of 100 % capacity ), it is recommended that
a 3 stage charger may be used (Constant current bulk charging followed by constant
voltage boost / absorption charging followed by constant voltage oat charging )
Batteries, alternators and isolators on vehicles / RVs
It is recommended that for powering the inverter, one or more auxiliary deep cycle
batteries should be used that are separate from the SLI batteries. The inverter should
be powered from the deep cycle batteries. For charging the SLI and the auxiliary
deep cycle batteries, the output from the alternator should be fed to these two sets
of batteries through a battery isolator of appropriate capacity. The battery isolator
is a device that will allow the alternator to charge the two sets of batteries when
the engine is running. The isolator will allow the inverter to be operated from the
auxiliary batteries and also prevent the SLI batteries from charging the auxiliary deep
cycle batteries when the engine is not running. Battery isolators are available from
auto / RV / marine parts suppliers
A majority of smaller vehicles have 40 to 105 Ampere alternator and RVs have 100
to 130 Ampere alternator. When in use, the alternators heat up and their output
current capacity can drop by up to 25%. When heated up, their charging voltage may
also not reach the desired absorption voltage and will result in return of only about
80% of the battery capacity. In case the current output of the standard alternator is
not adequate to charge the two sets of batteries rapidly and fully to 100% of their
capacity, use heavy duty alternator that can produce higher current and voltage
required to charge multiple battery systems. These alternators are available with auto
/ RV parts suppliers
Page18

INSTALLATION
Page 19
GENERAL
Installation and wiring compliance
• Installation and wiring must comply with the local and the national electrical codes and must
be done by a certied electrician
• In building / residential applications, electrical codes do not allow permanent connection of
AC distribution wiring to the inverter’s AC output receptacles. The receptacles are intended
for temporary (as needed) connection of cord connected loads only. Read details under “AC
Power Distribution and Grounding” on page 9.
• The inverter does not have integral over current protection for the AC output side.
Protection should be provided by the installer
• Over current protection of the cables from the battery to the inverter has to be provided by
the installer
• The DC input positive and negative terminals are isolated from the chassis. Similarly, the
neutral pole of the AC receptacles / the neutral wire is not bonded to the chassis. System
grounding to suit the national / local electrical codes is to be undertaken by the installer.
Read details under“AC Power Distribution and Grounding” on page 9.
Preventing electrical shock
• Always connect the grounding connection on the inverter to the appropriate
grounding system. Read details under“AC Power Distribution and Grounding” on
page 9.
Installation environment
• The inverter should be installed indoor only in a well ventilated, cool, dry
environment
• Do not expose to moisture, rain, snow or liquids of any type.
• To reduce the risk of overheating and re, do not obstruct the suction and
discharge openings of the cooling fan.
• To ensure proper ventilation, do not install in a low clearance compartment
• Working with the inverter may produce arcs or sparks. Thus, the inverter should
not be used in areas where there are inammable materials or gases requiring
ignition protected equipment. These areas may include spaces containing
gasoline powered machinery, fuel tanks, battery compartments
Mounting position of the inverter
• The inverter may be mounted horizontally on the top of a horizontal surface or
under a horizontal surface. The inverter may be mounted on a vertical surface
only horizontally (the fan axis should always be horizontal i.e. the fan should
not be pointing up or down)
Cooling by forced air fan ventilation
The inverters produce heat when operating. The amount of heat produced is
proportional to the amount of power supplied by the inverter. DC fans are used to
provide forced air cooling of these inverters. The fans are thermostatically controlled
and will be switched on only if the temperature of certain hot spot inside the
inverter rises above a certain temperature. At lower loads and / or at lower ambient
temperatures, the fan may not switch on at all. This is normal. The units are protected
against over-temperature due to failure of the fan / inadequate heat transfer. The AC
output will be shut-down if the hot spot inside the inverter reaches a certain higher
temperature.