When looking at the purchase cost of motors it’s easy to get distracted and focus solely on the purchase price, ignoring the running costs and potential energy savings possible by choosing a more efficient IE3 motor over an IE2 motor.
With tight budgets it may even seem to make sense to choose the cheaper option, but it really is a false economy.
To look at the costs and savings involved we’ll take a look first of all at a small 5.5kW motor, assuming Mon-Fri operation at 8 hours per day and a unit electricity cost of 10p per kWh, and then look at a larger 20kW motor, finally we’ll take a look at much larger 160kW unit.
| TEC T2C 132S-4 5.5kW, 4 pole IE2 motor | TEC T3A 132S-4 5.5kW, 4 pole IE3 motor | |
|---|---|---|
| Original Purchase price | £247.63 | £263.89 |
| Motor/efficiency* | 5.5kW/87.7% = 6.27kW | 5.5kW/89.6% = 6.13kW |
| Annual run time | 8 hours per day x 5 days per week x 52 weeks = 2,080 hours per year | 8 hours per day x 5 days per week x 52 weeks = 2,080 hours per year |
| Annual Energy use | 6.27 x 2,080=13041.6 kWh | 6.13 x 2,080 = 12750.4 kWh |
| Running cost (assuming 10p unit cost per kWh) | 13041.6 kWh x 10p = £1304.16 | 12750.4 kWh x 10p = £1275.04 |
| Total operating cost (based on 15 years) | £1304.16 x 15 = £19562.40 | £1275.04 x 15 = £19125.6 |
| Total savings using an IE3 motor: | £436.80 | |
*Efficiency at 100% load
As can be seen, an initial additional cost of £16.26 results in a saving of £436.80 over the life span of the machine, not forgetting that the use of more efficient motors will support your companies environmental policy.
The savings increase with the size of the motor, stepping up to a 22kW motor shows an appreciable saving which is the equivalent of getting a free motor.
| TEC T2C 180L-4 22kW, 4 pole IE2 Motor | TEC T3C 180L-4 22kW, 4 pole IE3 motor | |
|---|---|---|
| Original Purchase price | £652.81 | £693.01 |
| Motor/efficiency* | 22kW/91.6% = 24.01kW | 22kW/93% = 23.65kW |
| Annual run time | 8 hours per day x 5 days per week x 52 weeks = 2,080 hours per year | 8 hours per day x 5 days per week x 52 weeks = 2,080 hours per year |
| Annual Energy use | 24.01 x 2,080=49940.8 kWh | 23.65 x 2,080 = 49192 kWh |
| Running cost (assuming 10p unit cost per kWh) | 49940.8 kWh x 10p = £4994.08 | 49192 kWh x 10p = £4919.20 |
| Total operating cost (based on 15 years) | £4994.08 x 15 = £74911.20 | £4919.20 x 15 = £73,788.00 |
| Total savings using an IE3 motor: | £1123.20 | |
*Efficiency at 100% load
And finally to look at the savings with a much larger 160kW motor
| TEC T2C 315L1-4 160kW, 4 pole IE2 Motor | TEC T3C 315L1-4 160kW, 4 pole IE3 motor | |
|---|---|---|
| Original Purchase price | £4177.40 | £4434.72 |
| Motor/efficiency | 160kW/94.9% = 168.59kW | 160kW/95.8% = 167.01kW |
| Annual run time | 8 hours per day x 5 days per week x 52 weeks = 2,080 hours per year | 8 hours per day x 5 days per week x 52 weeks = 2,080 hours per year |
| Annual Energy use | 168.59 x 2,080=350667.2 kWh | 167.01 x 2,080 = 347380.8 kWh |
| Running cost (assuming 10p unit cost per kWh) | 350667.2 kWh x 10p = £35066.72 | 347380.8 kWh x 10p = £34738.08 |
| Total operating cost (based on 15 years) | £35066.72 x 15 = £526000.80 | £34737.08 x 15 = £521071.20 |
| Total savings using an IE3 motor: | £4929.60 | |
*Efficiency at 100% load
The savings over time are far from inconsequential, especially with the larger sized motors, making IE3 the sensible choice, both financially and environmentally.
Within the EC from January 2017, new motors in the range of 0.75 kW to 375 kW have to be IE3 unless driven by variable speed control, then IE2 can be used.