Three-phase motors account for around 24% of New Zealand's total electricity use. Typically, these motors are more than 10 years old and up to 14% less efficient than new motors on the market.
A pilot project in 2006 indicated that when they fail, more than two thirds of these motors are repaired and returned to service, even when it's more cost effective to replace them. Improving the way machinery is commissioned and maintained, is estimated in international studies to save 10% to 15% of a company's electricity use.
Electric motor efficiency in action
Case study: Nelson Pine Industries - Improving motor controls and increasing profits
Installing variable speed drives on Nelson Pine Industries' fan systems delivered cost savings with a less than two year payback. Six months after installation, monitoring showed electricity use had reduced by 1,400,000 kWh pa for a typical production year - a 51% decrease. Read the case study.
Case study: Timing of pump replacement
As pumps age, reliability can become an increasing concern for businesses. The risk of unplanned downtime can be reduced by replacing pumps at the optimal time; monitoring in-service pumps for deterioration is also important. This guide focuses on a pump replacement project at door and window hardware manufacturer Assa Abloy. Read the case study.
Getting the best from your electric motors
Improve the energy efficiency of motors and motorised systems in your business, with these guidelines and resources:
Develop a motor replacement policy
When faced with in-service motor failures and/or aging motors that risk failure, businesses need to decide whether it's better to replace or repair motors. EECA’s Motor Replacement Policy Guide helps you develop a policy to support making these decisions. EECA has also developed a replacement payback calculator for electric motors. Read more and download the Motor Replacement Policy Guide.
Use quality-certified motor rewind workshops
Motor rewinding is an important part of good motor maintenance. However, poor quality rewinding can endanger motor efficiency and reliability. For example, a 55kW motor may lose 3 percentage points of efficiency through a poor quality rewind. If that motor then runs fully loaded for 6,000 hours per year the electricity loss could cost $1,200 per year (at 12 cents per kWh).This is before any costs resulting from reduced reliability and increased need for maintenance.
To help safeguard the efficiency of New Zealand's industrial motors, EECA supports quality certification of workshops that offer motor rewinding services.
Take note of energy performance standards
Minimum energy performance standards (MEPS) for three-phase electric motors were introduced in New Zealand in 2002. The standards were revised in 2006 and another revision is proposed for 2011.
This means importers and manufacturers may not sell three phase electric motors unless they are tested and comply with the Energy Efficiency (Energy Using Products) Regulations 2002.
In addition to specifying minimum efficiency values for motors, the Standard also specifies the minimum efficiency that a motor needs to meet in order to be able to claim ‘high efficiency'. Find out more about MEPS for three-phase motors.
Consider electronic soft starters
Starting a motor without any control of the current and torque is referred to as direct on line (DOL) starting. A DOL start typically causes motor current more than six times the rated current. The starting torque is also much higher than the rated torque of the motor, creating high loads that can stress mechanical components such as couplings and shafts. With larger motors, high starting currents can lead to flickering lights and unacceptable voltage drops across a site.
Electronic soft starters, which work by reducing the voltage supplied to the motor, provide one means of addressing these motor starting issues. Read more about electronic soft starters.* Industrial Motors Efficiency Pilot Project, Electricity Commission 2006
Help from EECA
Education and training
EECA supports a range of training, education and audit standards relating to motor systems efficiency in New Zealand industry. Find out about EECA’s industrial training courses and webinars.