Induction motors run efficiently when they are running flat out fully loaded.
When a traditionally controlled on line / off line rotary screw compressor is operating on line it's making air at 100% load and the motor works efficiently. However once the system pressure has been reached the machine will un load and operate off line.
In this mode the compressor will not make any air but will still consume power. The motor turns the rotors in the air end and keeps the machine lubricated. In this mode the compressor will consume up to 25% of full load power to produce nothing.
As the system pressure falls the compressor will eventually load and make air again and the cycle is repeated.
A variable frequency drive eliminates the costs of unloaded operation and over pressurisation. Why supply air at 7 barg if you only need it at 6.5barg.
For every 1 bar reduction in system pressure you can save 7.5% power.
The VFD does this by speeding up or slowing down the motor to maintain a target pressure in the main plant receiver. So, the compressor will then only consume the power required to meet the air demand and you'll generally save 25% power. The more unloaded power cost you have the more you'll save.
VFD's can be fitted on any motor where this is a variable load. Pumps & Fans for example.
Payback Periods: 3 to 18 months
Installations: 4 to 300 KW
2 Year Warranty
100% Capital Allowance Qualifying
Return on investment can easily be justified and should your company qualify we can support your application for an interest free loan through the Carbon Trust. The loan repayments would be made from the energy savings so it costs you nothing!. It's a no Brainer!
Visit the Carbon Trust website ›
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