In your factory or offices you will find electric motors all over the place. They drive the air compressor that supply your factory’s air and power the fans that blow the air in your offices from your air conditioning. They are the thing that you switch on in the morning and off in the evening and take for granted. Fortunately electric motors and in particular AC induction motors (90% of all the motor in industry and offices) are a very reliable workhorse and rarely let you down. When they go wrong you can usually find a replacement cheaply and easily without too much fuss.
So why mess with something that is so reliable? You know the old adage, ‘if it ain’t broke don’t fixit?’
Why Use an Inverter
Well, it is simple really, they cost you money. When your system was designed, engineered and installed an engineer would have given very careful consideration to the requirements of the system and worked out what size motor was needed. Unfortunately there almost certainly wasn’t a motor available to meet his exact calculations and he had to pick a motor from a standard set of sizes. This meant going to the next size up, a bit like buying anything really as you rarely ever find the perfect requirements ‘off the peg’.
What this means is that nearly every motor installed is too big for the exact requirements of what the system was designed to do. This is doubly important as most fans and pumps are rarely ever made to measure and come in standard sizes as well. So you end up with a fan or pump slightly too big fitted with a motor that is slightly too big as well. It is then normal to restrict the flow by some sort of mechanical limits, for example a damper or venturi. Ok this saves a little bit of money but the motor and fan or pump are still going along at the same fixed speed as this is determined by the mains frequency and the number of poles in the motor. What if you could change the speed of the motor to change the flow of your pump or fan? You can hardly ring up your electricity supplier and ask them to change the mains frequency or change the motor every time you wanted to slow things down so you need something else.
That something else is an inverter. They have lots of other names as well: drive, VSD, frequency converter and so on. We put this between the mains and your motor and that allow us to vary the speed of the motor and open up all of the restrictions and allow your fan or pump to operate in the way it was originally designed. This can save a lot of money. For a typical centrifugal fan or pump you can save more than 25% of the energy used by reducing the speed by 10% and by reducing the speed by 20% you can save up to 50% of the energy. The payback on your investment can be as little as a few months. WHY WASTE MONEY FIT INVERTERS.
Lots of other things that have motors can have inverters and not always to save money. For example you might have one conveyor feeding another so fitting an inverter to one of them can make them go at the same speed. This saves money as well really as your goods are not damaged when the go from one conveyor to another.
A lot of companies now look very hard at saving money and control their process more accurately. Here are a few examples where inverters can be retro-fitted to save money:-
Air compressors 10-15%
Hydraulic power packs 10-15%
Extract fans – up to 50%
Supply fans – up to 50%
If you would like clarification on any of the points raised in this article or if you would like to book an energy efficiency motor audit please contact our inverter engineers on 0115 944 1036 or email [email protected]