Electrical motors are one of the significant high electricity consumption loads and present almost in all electricity application systems as far as they represents nearly 60 % of total loads in industrial electricity application.
Now I will tell you briefly two ways (passive and active efficiency) that can efficiently reduce electricity consumption of electrical motors and their applications like fans, pumps and compressors.
Passive Energy Efficiency to Reduce Motor Electricity Consumption:
Reducing electricity consumption can be done by doing the following:
1-Stop motor if you don’t need it as it consume electricity at no load.
2-Try to not oversize electrical motor and use the optimal (kW) power motor that suit your electrical load demand (60 % - 100 % loading percent is the optimal) as this will lead to waste electricity uselessly.
3-Replace the older, less efficient, rewinding motor with anew more efficient one as the most efficient motor can improve efficiency by 10 % and motor subjected to rewind is less efficient by 3 % to 4 % compared to original one, If the efficiency increases electricity waste reduces.
4-It’s very important to review the coupling between motor and the drive chain as 0.6 mm aligning of the shaft will lead to nearly 8% more electricity losses.
Active Energy Efficiency to Reduce Motor Electricity Consumption:
Very intelligent with high amount of electricity saving,… your electrical motor is working at full speed to meet your max demand of flow in fan or pump or other application but sometimes you needn’t this max flow so you use a valve or a damper or a throttle to reduce the flow of fluid by making friction losses that consider an energy waste. If you use variable speed drive to control the flow of the fan or pump you will save much electricity.. Let me approve this to you by affinity laws which stated that:
Flow is proportional to electrical motor shaft speed.
Pressure is proportional to electrical motor shaft speed square.
Motor electricity consumption is proportional to motor shaft speed cubed.
So if you reduce the electrical motor shaft speed to the half, the flow will reduce to the half also, pressure will reduce to the quarter and fantastically energy consumption by the motor will reduce to one eighth.
So it is very obvious now that small reduction in motor shaft speed (flow or pressure) will lead to significant reduction in electricity consumption.
More Electricity Saving by Using Variable Speed Drives in Conjunction with Control Devices:
Many other electricity saving advantages can be obtained when we use control devices with variable speed drives to meet individual requirement.
For example, at water distribution systems control devices will change the flow of the motor throw variable speed drive according to the value of the flow and pressure required in the piping system.
Another example is in heating and cooling system as the control device will change motor flow throw variable speed drive according to the temperature value, also as a third example in pumping application systems ,control devices will change the flow throw variable speed drive according to to pressure difference come from level difference .
Advantages of Using Control Devices in Conjunction with Variable Speed Drives:
1-Greater accuracy of pressure and flow values.
2-Reduce transient effect in electrical networks and reduce motor vibration.
3-More smoothing in start and stop motor operation.
Ultimately of course significant reduction in electricity consumption can be achieved with a little regard to electricity consumption of electrical motors and its applications especially fans and pumps.
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