Electric motor systems

Get more grunt for less energy by running your electric motor as part of a bigger system.

THE MOTOR IS PART OF A BIGGER PICTURE

If you have a system run by an electric motor – such as a pump, fan or compressed air system – there are bound to be ways to save costs, energy and emissions. But the motor itself may not be the easiest place to find them.

Most electric motors are highly efficient – and all new three-phase electric motors sold or hired in New Zealand (0.73kW-185kW) must comply with Minimum Energy Performance Standards (MEPS), so you’re guaranteed a minimum standard of efficiency. Once you’ve invested in an efficient motor, focus on the whole system – how it’s installed and how it’s operating.

Compressed air

Pumping and fan systems

MEPS factsheet

Use quality-certified motor rewind workshops

Rewinding an old motor revitalises it and can restore efficiency – but it has to be done well. A poor quality rewind to a 55kW motor can result in a 3% reduction in efficiency. If that motor then runs fully loaded for 6,000 hours per year, you’ll be wasting energy worth around $1,200 a year (at 12 cents per kWh). Reduced reliability and increased maintenance can cost you more on top of this.

Make sure you only use rewinders who are quality certified with either:

  • ISO 9001 Quality Management System
  • Telarc Motor Rewind Workshop Quality Code.

 

A policy eases motor replacement decisions

If you often need to replace or repair older, lower-efficiency three-phase motors, invest time in developing a site-wide motor replacement policy that pins down your priorities, such as efficiency and payback period. The policy can then guide decisions whenever an in-service motor fails or is reviewed as part of a preventative maintenance programme, and help you make consistently good business decisions.

 

Minimise energy losses from electronic soft starters

Electronic soft starters reduce the stress load on electric motors caused by direct on line (DOL) starting. They reduce the voltage supplied to the motor – but they result in energy losses of about 0.7%.

You can eliminate unnecessary energy losses by having an internal or external contactor electrically bypass or bridge out the SCR’s soft starter once the motor reaches its full speed. Some soft starters include a built-in bypass contactor, others require an external bypass contactor.