Hello everyone, i am a trained engineer specialized in installing inverter for homes and office in Benin city. I have lots of experience dealing with client in usage of this systems and how they can be maintained for 10 years of running.

If you are thinking of installing an inverter in your home and office and be sure of 8 hours of electricity, follow this most frequently asked questions and answers.

Sit back and enjoy the lectures , i promise to make it easy for non-engineers


1 What size of inverter do I need for my home/office?
Choosing the right size of inverter depends on the power requirements of the appliances you expect to operate at any given time. You should consider both the continuous and surge power rating of your appliance. The continuous rating must be high enough to handle all the loads that may run at the same time. The inverter must also be capable of handling the starting surge of all loads that may start at the same time. Loads typically take many times their continuous rating to start.

Now let me explain continuous and surge rating.
Surge is the maximum power that the inverter can supply, usually for only a short time - a few seconds up to 15 minutes or so. Some appliances, particularly those with electric motors, need a much higher startup surge than they do when running. Pumps are the most common example - another common one is refrigerators (compressors).

Continuous rating is what the inverter has to supply on a steady basis. This is usually much lower than the surge. For example, this would be what a refrigerator pulls after the first few seconds it takes for the motor to start up, or what it takes to run the microwave - or what all loads combined will total up to.

Example
1 If an 800VA/12v inverter has a surge rating of 1200VA. it means it can carry an appliance of 1000VA for 10 seconds before it trips off

2 A refrigerator may be rated 120W and the surge 400W. This means that when you switch on your refrigerator, it will use up 400w[surge] for a few seconds then drops to 120W[continuous] for steady operation.

Note that different brands of inverters have different surge rating.

2 Whats the difference between UPS and Inverter?
This is one of the basic confusion people face, so let me start with answering this first. UPS and Inverter are words used interchangeably though there are not exactly same. UPS (Uninterrupted Power Supply) is just a system which allows INSTANT switchover to the power back-up source in case of a power failure. The power back-up source can be a battery or something else. Whereas an Inverter is a system which converts direct current to alternate current hence enables using a battery for backing up equipments running on AC power supply. Inverter uses a battery to provide power back-up. Computer UPS comes with in-built battery which works as back-up power source and can provide back-up for 15min. to 30 min. So if that much of back-up is sufficient for you, you should be fine with buying just a UPS for your need. But Inverter comes with more powerful battery and can provide support for electrical equipments, computers, home appliances etc. and also gives more hours of back-up. Most of the inverters come with in-built UPS which ensures that power failure doesn't cause fluctuation and your system switches instantly to Inverter's Power Back up battery.

3 What is the difference between Sine Wave, Modified Sine Wave, and Square Wave Inverter?

There are 3 major types of inverters - sine wave (sometimes referred to as a "true" or "pure" sine wave), modified sine wave (actually a modified square wave), and square wave.

o Sine Wave
A sine wave is what you get from your local utility company and (usually) from a generator. This is because it is generated by rotating AC machinery and sine waves are a natural product of rotating AC machinery. The major advantage of a sine wave inverter is that all of the equipment which is sold on the market is designed for a sine wave. This guarantees that the equipment will work to its full specifications. Some appliances, such as motors and microwave ovens will only produce full output with sine wave power. A few appliances, such as bread makers, light dimmers, and some battery chargers require a sine wave to work at all. Sine wave inverters are always more expensive - from 2 to 3 times as much.

o Modified Sine Wave
A modified sine wave inverter actually has a waveform more like a square wave, but with an extra step or so. A modified sine wave inverter will work fine with most equipment, although the efficiency or power will be reduced with some. Motors, such as refrigerator motor, pumps, fans etc will use more power from the inverter due to lower efficiency. Most motors will use about 20% more power. This is because a fair percentage of a modified sine wave is higher frequencies - that is, not 60 Hz - so the motors cannot use it. Some fluorescent lights will not operate quite as bright, and some may buzz or make annoying humming noises. Appliances with electronic timers and/or digital clocks will often not operate correctly. Many appliances get their timing from the line power - basically, they take the 60 Hz (cycles per second) and divide it down to 1 per second or whatever is needed. Because the modified sine wave is noisier and rougher than a pure sine wave, clocks and timers may run faster or not work at all. They also have some parts of the wave that are not 60 Hz, which can make clocks run fast. Items such as bread makers and light dimmers may not work at all - in many cases appliances that use electronic temperature controls will not control. The most common is on such things as variable speed drills will only have two speeds - on and off.

• Square Wave
Very few but the cheapest inverters are square wave. A square wave inverter will run simple things like tools with universal motors without a problem, but not much else. Square wave inverters are seldom seen any more.

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4 Should I leave my inverter ON or OFF when PHCN is available?
When PHCN is available, you may leave your inverter ON or OFF. There are advantages and disadvantages to both methods. If the inverter is left ON, you have immediate backup AC power if you lose PHCN. You may not be aware PHCN is lost until your batteries are fully discharged. If you choose to leave your inverter OFF you have the advantage of knowing when you have lost PHCN. This, however, is at the expense of losing automatic backup power capabilities.

5 What is Three-Stage Charging?

First lets see the meaning of Life Saving Charge
This charging stage applies only, if for some reason, your battery has gone under deep discharge conditions. In this mode (until battery reaches to a minimum specified charge level) the charging currents is very low to avoid any excessive heat produced inside the battery. It is kept very low because the battery internal resistance is very, very high and using a high charging current may cause a rapid rise in the internal battery temperature which would shorten its life. This technique or method of using low charging current will not reduce your battery life cycle if your battery has gone under deep discharge condition.

[b]
Multistage charging [/b]ensures batteries receive best and favourable charging, but with minimal wear and tear, regulating the voltage and current delivered to the batteries in three automatic stages:

Bulk Charge
In Bulk charging stage, the inverter unit charges the batteries at the full charging current. i.e. 12 AMPS, so that this charging takes place at the fastest possible speed

Absorption Charge
The second stage of charging is Absorption. When the battery is 80% charged the Microtek unit will start reducing the charging current of the batteries in the steady fashion. As the battery is being charged to 100%, charging is reduced to negligible current.

Float / Trickle Charge
The third stage of charging is Float charging. This is when the battery is 100% charged, a charge is required just to take care of the self-discharge of the battery. This is often referred to as maintenance charge, as it does not charge the battery but keeps an already-charged battery from self-discharging.


In summary:
Bulk: Replaces 70-80% of the battery’s state of charge at the fastest possible rate.
Absorption: Replenishes the remaining 20-30% of charge, bringing the battery to a full charge at a slow, safe rate.
Float: Voltage is reduced and held constant in order to prevent damage and keep batteries at a full charge.

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Yes boss

6 What appliances do most people power during an outage?

In residential settings, refrigeration, gas- or oil-fueled heating systems, and lighting are most common. Electronic appliances such as computers, home entertainment components, and security systems don't consume much electricity and can easily be added to a home's backup subpanel. If you use pumps to supply water, keep a basement dry or pet fish alive, include these items in your backup power plans. Many gas appliances require only a small amount of electricity and should be included on the sub-panel. Comfort and convenience appliances such as fans, coffee makers, microwave ovens and garage door openers are other items your may want to use during an outage.

In an office setting, computers, printers, modems, fax machines and telephone systems are the most common equipment to run along with lighting. It makes sense to include whatever you need to keep your business functioning efficiently. Just remember that the more things you power, the bigger your system will need to be.

7 What Feature makes a good Inverter?

By Feature, i mean what qualities makes an inverter Durable and last for many years. This qualities i am going to explain is the main reason while i prefer installing foreign inverters to locally made inverter.

There are 4
Short Circuit Protection
Overload Protection
Battery Deep Discharge Protection
Battery Reverse Polarity Protection

Short Circuit Protection
In mains mode MCB connected at the output of inverter disconnects the load connected to the inverter, in case of short circuit overload.
A short circuit means an abnormal connection between two nodes of an electric circuit with infinite resistance. This results in an excessive electric current/overcurrent and can be dangerous. A good inverter will trip off to avoid damage to your appliances.

Overload Protection
If the load exceeds the capacity of your inverter, the electronic overload protection works and inverter trips automatically. After reducing the load manually, resetting the “RESET” Switch, the inverter starts operation again.

Battery Deep Discharge Protection
The protection operates when battery voltage goes below 10.3V + 0.1V in the 12V system and 20.6V + 0.1V in the case of the 24V system. At this voltage the inverter stops running on battery and no output is available, so batteries are protected from further discharge. In this case output from the inverter is available only on resumption of mains.

Battery Reverse Polarity Protection
If batteries are connected on the polarity reverse, the HRC fuse inside the inverter will be blown, therefore protecting the inverter.

Lets Do some Basic Calculation, but first i want you to understand this electrical terms

Watts
The power and watt is often misunderstood. Watts are basically just a measure of how much power a device uses when turned on, or can supply. A watt is a watt - there is no such thing as "watts per hour", or "watts per day". If a something uses 100 watts, that is simply the voltage times the amps. If it draws 10 amps at 12 volts, or 1 amp at 120 volts, it is still 120 watts. A watt is defined as one Joule per second, so saying watts per hour is like saying "miles per hour per day".

Watt-hours
A watt-hour (or kilowatt hour, kWh) is simply how many watts times how many hours that is used for. This is what most people mean when they say "watts per day". If a light uses 100 watts, and it is on for 9 hours, that is 900 watt-hours. If a microwave uses 1500 watts, and runs for 10 minutes, that is 1/6th of an hour x 1500, or 250 WH. When you buy power from your friendly utility (look at your last bill), they sell it to you at so much per kWh. A kWh is a "kilowatt hour", or 1000 watts for one hour (or 1 watt for 1000 hours).

Amps
An amp is a measure of electrical current at the moment. (Amps do not come in "amps per hour" or "amps per day" either). Amps are important because it determines what wire size you need, especially on the DC (low voltage) side of an inverter. All wire has resistance, and amps flowing through a wire makes heat. If your wire is too small for the amps, you get hot wires. You can also get voltage drops in the wire if it is too small. This is not usually a good thing. An amp is defined as 1 Coulomb per second.

A Coulomb is the charge of 6.24 x 1018 electrons. Therefore, 1 Amp is equal to the charge of 6.24 x 1018 electrons passing a point in a circuit in 1 second.

Amp-Hours
Amp-hours (usually abbreviated as AH) are what most people mean when they say "amps per hour" etc. Amps x time = AH. AH are very important, as it is the main measure of battery capacity. Since most inverters run from batteries, the AH capacity determines how long you can run. See our battery page for much more detailed information

Current
The rate of flow of electrical charge. The flow of amps is often expressed as current.

High Battery Protection
A control circuit that disconnects charging current flowing to battery (s) when voltage reaches a dangerously high threshold. Prevents damage created by excess gassing (or boiling) of electrolyte.

Kilowatt (kW)
One thousand watts of electricity.Ten-100 watt light bulbs use one KILOWATT of electrical power.

Kilowatt Hour (kWh)
One KW of electrical power used for one hour. The most common measurement of electrical consumption, most electrical meters measure KW/H for billing purposes.

Line Loss
A voltage drop caused by resistance in wire during transmission of electrical power over distance.

Load
Any device that consumes electricity in order to operate. Appliances, fans and lights are examples of electrical loads. The amount of power the equipment is drawing from the inverter at any given time.
e.g. if you have an 800W inverter and drawing 400W, your inverter is running at half its load.

Low Battery Protection
A control circuit that stops the flow of electricity from batteries to loads when when battery voltage drops to dangerously low levels.

Overload / Over Current Protection
A control circuit is designed to protect an inverter or similar device from loads exceeding its output capacity ( i.e A fuse is an over current protection device )Inverters have internal circuitry to protect themselves from overload / over current conditions.

Exercise.
I am going to do some calculation based on my last project.

A woman complained about the PHCN condition in an her area. It has gotten so bad that they barely have four hours of light everyday. Her small Elemax generator was so overworked that it finally gave up in April. She switched it on at 7pm and switch it off at 12 midnight. At a time, the heat at night was so terrible, her kids would wake up crying and itching from the heat rash. Sometimes she would wake up at 2am and wouldn't be able to sleep. Some of the people in her area alleged that PHCN was diverting power to other neighbourhoods that were paying bribes. They hoped the situation would improve but alas it only got worse.

So what did I do? .

For optimum result i had to consider 3 factors

a) Since inverters depend on PHCN and generator for charging, i had to factor out how many hourse of electricity would be required to charge the battery. For this case, she got 4 hrs from PHCN and 3hrs from generator. that is 7 hours.

b) I had to estimate the load of her household to determine the size of the inverter

c) i had to consider the nos of hrs she would want the electricity on. this would determine my power capacity.

1 The Load
5 units * Energy Saving Bulb @ 20W each
3 units * Fan - 70W @ each
1 unit * Television - 120W
1 unit * Dstv Decoder - 10W

2 Time
The time she needed it to run was from 11pm to 6am [7 hours]


From this data, i need to calculate the following:
1. Calculating your power need
2. Calculating required inverter's capacity
3. Calculating battery capacity

very educative, keep up d good work.

djaybaba: very educative, keep up d good work.

Thanks

How To calculate the power for Inverter

1. Calculating your power need
Now I'll explain you how to use above table to calculate the right capacity Inverter for your need. Let's say you need Inverter to run 5 Tube lights, 3 Fans, 1TV and 1 Decoder.

As per the table above, you'll need a total power of
(5X20 + 3X70 + 1X120 + 1X10) = 440W

This will support all your equipment at the same time.
♣ Your Total Power Need = 440W

2. Calculating required inverter's capacity

Now that you know how much power is required, it's easy to get the VA rating of inverter. In ideal condition, the VA rating would have been same as the power need i.e. 440VA. But in practical conditions, the power factor of Inverter is less than 1 hence power supplied by 440VA Inverter won't be 550W but lesser than that. Assuming power factor of Inverter to be 0.7, following are the details of calculation -

Required VA of Inverter X 0.9 = 440W
♣ Required VA of Inverter = 440/0.9 = 488 VA

Now luckily we have inverters available in the market with 800VA capacity, so such inverters will fit into my requirement.

3. Calculating battery capacity

Till now, you will have clear understanding of the Inverter capacity required for your need. But the next question is that how much back up will the inverter provide and for how many hours you can run all of your equipments. And that's where battery capacity comes into picture. It's the battery which determines the back-up hours. The higher capacity battery you have, the more back-up hours you'll get. So lets get into the calculation fast.

Required power(in Wattage) X Required back-up hours(in Hours) = Inverter Voltage(in Voltage) X Battery Capacity (in Ampere Hours)

Let's look for an Inverter which can give back-up of up to 3 hours, so for our case -

488W X 7 Hours = 12V X Battery Capacity

♣ Battery Capacity = (488 X 7)/12 = 284 Ampere Hours

So we need a battery of 284AH capacity but if you check the market you won’t find any battery of 284AH capacity.
We have 12V/100AH and 12V/200AH Batteries available, there is nothing like 12V/284AH

So what do we do?

Pls help. Just bought a Mercury 1200pro ups. My decoder and LED tv are plugged in but when power does out the decoder also goes off. The tv stays on. What's wrong here? What am I not doing right?

Please what is the size of inverter do I need to power my AC?

Pls help. Just bought a Mercury 1200pro ups. My decoder and LED tv are plugged in but when power goes out the decoder also goes off. The tv stays on. What's wrong here? What am I not doing right?

nice one bro...it's really superb

Deltaicc:
Please what is the size of inverter do I need to power my AC?

Depending on the horse power of your AC converted to watts. You'll need an Inverter of 1200watts to 2500watts to handle an AC with more than one 12v 200AH batteries connected in parallel.

OP this is the best thread I've seen sofar on thus topic. My eye done clear now.

Pls don't tell me you are gone. We still need more from you.

Nice thread let's also give hand to people so that quacks will not destroy our gadgets.

Spike88:
Pls help. Just bought a Mercury 1200pro ups. My decoder and LED tv are plugged in but when power does out the decoder also goes off. The tv stays on. What's wrong here? What am I not doing right?

Let's know the rating of your LED and decoder

Can one use a USA 240V 60HZ multi split inverter AC in Nigeria's 240V 50Hz power supply? Thanks.

Yes you can. Provided the equipment you want to power is rated for dual frequency (ie 50/60hertz). Else you'll have a roast.

Juokorow:
Can one use a USA 240V 60HZ multi split inverter AC in Nigeria's 240V 50Hz power supply? Thanks.

Hello great minds in the house.
Jst wanna ask this question going through the mail trails above. Identifing Battery capacity... With 12v inverter, 488watts of load and 7hrs of expected use. We got 285amps I. e you need 2pcs of 200amp battery. While using same . That means using a 24v of inverter with same parameters we'll get 142amps of battery I. e 2pcs 100amp battery. Finally this shows that 24v inverter is much better can also deliver more. Please kindly confirm if my calculations and inference conforms with reality. Thanks to all.

Hello, I have a 3.5kva inverter for sale call 09097790817

[s.

OracleHex:
4 Should I leave my inverter ON or OFF when PHCN is available?
When PHCN is available, you may leave your inverter ON or OFF. There are advantages and disadvantages to both methods. If the inverter is left ON, you have immediate backup AC power if you lose PHCN. You may not be aware PHCN is lost until your batteries are fully discharged. If you choose to leave your inverter OFF you have the advantage of knowing when you have lost PHCN. This, however, is at the expense of losing automatic backup power capabilities.

Good day my able people.

I use a 1000WATS inverter which malfunctions in such a way that borders me.
The image of the front view is uploaded. Please refer.


Let me first define some terms/indicators on the inverter for a clear explanation.

1. Battery working indicator-The indicator shows its light when when there is power outage. When battery is working. It goes off when light is restored.

2. City Power Working (CPW) indicator-The indicator interchanges its light with Battery working indicator. It light goes off when there is power outage and vice versa.

NOW MY QUESTION:

Why does the CPW go off, cutting off power supply, even when there is power supply? This makes all my appliances go off like power outage when on bye pass. Please somebody help.

reopen thread pls