Inverter: An inverter is
an electronic power device that facilitates continuity of
electricity when mains power fails. The inverter is
supported by batteries as the power source. The batteries
are charged by the Inverter when the electricity is
available. When power fails the inverter converts the DC
power from the battery to meet the AC power requirement of
the User’s load.
An inverter has the following key elements
Mains Power sensing circuit: When the AC Power comes
below 110VAC or above 280VAC or if there is a total mains
failure, the system automatically switches to the back-up
source of power.
Battery charger: A module that charges the battery
when AC comes and prepares battery to give back energy in
case of mains power failure.
Inverter (DC-to AC converter): A system that would
convert the energy stored in the battery/batteries to give
back-up power to appliances i.e. 230VAC 50Hz.
Types of Inverter:
Modified Square Wave: Modified Square Wave (or
“Modified Sine Wave” and “Quasi Sine Wave”) output inverters
are designed to have somewhat better characteristics than
Square Wave units, while still being relatively inexpensive.
Although designed emulate a Pure Sine Wave output, Modified
Square Wave inverters do not offer the same perfect
electrical output. As such, a negative by-product of
Modified output units is electrical noise, which can prevent
these inverters from properly powering certain loads. For
example, many TVs and stereos use power supplies incapable
of eliminating common mode noise. As a result, powering such
equipment with a Modified Square Wave may cause a "grain" or
small amount of "snow" on your video picture, or "hum" on
your sound system.
Pure Sine Wave: Pure or True Sine Wave inverters
provide electrical power similar to the utility power you
receive from the outlets in your home or office, which is
highly reliable and does not produce electrical noise
interference associated with the other types of inverters.
With its "perfect" sine wave output, the power produced by
the inverter fully assures that your sensitive loads will be
correctly powered, with no interference. Some appliances
which are likely to require Pure Sine Wave include
computers, digital clocks, battery chargers, light dimmers,
variable speed motors, and audio/visual equipment.
Back up Time of Inverter: Backup Time delivered by an
Inverter depends on the Battery capacity connected to the
Inverter (keeping the load same).
The AH capacity of the battery and the load connected to it
(watts) will determine the back up time. For example: In the
above case if you connect 135 AH battery with the inverter
the back up time will be 2 and ½ Hours where as if you
connect 150 AH battery then the back up time will be 3
Hours. The back up time will increase if you use lesser
How to choose a right kind of battery?
Battery plays a major role in the working of an inverter.
Normally the following 3 types of batteries are used for
inverter applications. Deep Cycle Flooded Lead Acid Battery
(thick flat plate), Tubular Battery & VRLA (SMF) Battery.
Deep Cycle Flooded Lead Acid Battery - Also known as
thick flat plate batteries, these are considered to be
specialist batteries for the inverters. These batteries
require regular top-ups (once in 2-3 months) with distilled
water and a little bit of maintenance. These batteries give
medium to High Life.
Tubular Batteries - These batteries consists of
tubular plates and give very Long life (up to 5- 6 years) .
These also require minimum maintenance and regular top up.
These batteries are most suitable for longer and frequent
VRLA Batteries - These are widely used for UPS and
solar applications. Though many people use it for inverter
applications but it is not the best solution for areas
experiencing longer power cuts. These batteries are sealed
type and totally maintenance free. They give low to medium
In addition to the power and quality of Charger, life of a
battery is determined by the depth of discharge during each
cycle. One cycle comprises of the battery getting fully
charged using mains power and then discharge in the case of
power cuts. If the battery is only partially discharged
during each cycle then the cycle life will be much greater.
Further to that a battery’s shelf life is an important
factor which indicates that if a battery is lying with a
dealer for longer duration it requires to be recharged for a
specific duration with ample top up before it is used.
Temperature affects the performance of a battery as well.
High temperatures can thus provide increased performance in
terms of back up time, but at the same time the rate of the
unwanted chemical reactions will increase resulting in a
corresponding loss of battery life.