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Using a 40HP 600V Fan or Centrifugal Pump Application

Switching a 40HP, 600V fan from a Direct-On-Line (DOL) starter to a Variable Sine Wave Drive (VFS – the latest advancement in VFD Technology):

  • Running at 55Hz instead of 60Hz typically produces substantial cost savings on the monthly electrical charges due to the affinity law for fans and Centrifugal pumps, which states that power consumed drops cubically with speed reduction.
  • 11 Month ROI @ 55Hz: Save $547/month on the electrical bill when SmartD runs the fan at 55Hz instead
    of 60Hz speed. Calculation and conditions shown below.
  • 7 month ROI @ 50Hz: Save $987/month when using the same calculations and conditions but averaging
    50Hz.

Note that with this conservative 55Hz example, we are not yet including the following additional savings. With Smart-D VFS product (which can even exceed the basic savings calculated below):

  • The calculations for automating the speed variation below the fixed speed
  • The calculations for eliminating hard starts (inrush current draw)
  • Motor extended life from Smart-D’s Sine Wave power (not traditional VFD square waves)
  • Driven Equipment extended life due to the best available soft starting
  • Elimination of all external VFD filters and meeting IEEE-519 Hamonic mitigation at the VFD.
  • Reduced footprint and labour reductions for traditionally filtered VFD cabinets and MCCs

Power Reduction Calculation Example – Using a conservative 8% drop in speed (55Hz instead of 60Hz):
Running a fan at 55Hz instead of 60Hz means the speed 55⁄60 = 0.917 is reduced of full speed.
According to affinity laws, the power drawn by the fan drops by the cube of this ratio:

Power55Hz = Power60Hz × (55⁄60)3 ≈ 40HP × 0.77 = 30.8HP

Hence, the fan at 55Hz consumes about 77% of the power it does at 60Hz.

Monthly Savings Estimate
Assuming the fan runs continuously (24/7) and the efficiency (including motor and drive) is about 95%. Convert HP to kW for energy calculations:
1HP = 0.746kW
Full load power at 60Hz = 40HP × 0.746 ≈ 29.84kW

Power at 55Hz:
29.84kW × 0.77 ≈ 22.18kW

Energy usage per month (30 days, 24 hours per day):
EnergyDOL = 29.84kW × 24 × 30 ≈ 21,484kWh
EnergyVFD = P22.18kW × 24 × 30 ≈ 16,017kWh

So, anticipated monthly energy savings:
21,484kWh − 16,017kWh ≈ 5,467kWh

Assuming an Alberta commercial electricity rate of $0.10/kWh:
Monthly savings ≈ 𝟓, 𝟒𝟔𝟕kWh × $𝟎. 𝟏𝟎 = $𝟓𝟒𝟕

Actual savings may go up or down with fan load profile, utility rates, and seasonal usage patterns.

Summary Table

Operating ModePower Draw (kW)Monthly Energy (kWh)Estimated Cost (@$0.10/kWh)Monthly Savings
DOL, 60Hz29.8421,484$2,148—
VFD, 55Hz22.1816,017$1,602$547

Typical User cost for a SMART D SDB Series NEMA 1 VFD Panel (S3L Frame) with the following:

a. 1 VFD, 40HP, 600V, 44A, 110% OL
b. 1 Input Low harmonic Filtration system containing
c. 1 of a 3-Level Active Front End (For IEEE-519 Levels at the VFD <5% THDi)
with regeneration braking (no Dynamic Brake Resistor needed)
d. 1 Output Sine Wave and Common Mode filtration systems
e. 1 Touch Screen HMI (Programmable)
f. 1 Controls terminal block; 6 DI, 3 DO (1 Form C relay, 2 Form A relays), 2 STO DI, 3 AI, 2 AO
g. 1 Modbus TCP Ethernet native protocol software
h. 1 Ethernet IP native protocol software
i. 1 BACnet IP Ethernet native protocol software
j. 1 Pair of Ethernet Ports
k. 1 3C3 level Conformal Coating Treatment

NO MORE 6 to 8 ft Cabinets ↑

With the elimination of any Line & Load, filtering can now savespace and cost on cabinets.

Typical Price is $7,034 CAD per panel, before shipping costs.
Not including Installation, Start-up & Commission.

KEEPING THE PANEL SMALL ←

This SmartD VFS (VFD system) INCLUDES all possible Advanced Line & Load Filter options.

Filters are re-engineers to be embedded at the PCB (Solid State) level.

APPENDIX – SAVINGS ON VFD PANELS
Adding Filtration can make your Panel or MCC much larger and more expensive than it needs to be.

SHRINKING THE VFD PANEL FOOTPRINT:
ELIMINATE THE NEED FOR EXTERNAL FILTERS

A TRUE SINE WAVE IS DRAWN FROM THE GRID
A TRUE SINE WAVE IS GIVEN TO THE MOTOR

This upgrade in technology means we can do the following:

  • Keep healthy old motors and cables in place.
  • Allow unlimited cable lengths to the motors.
  • Eliminate the need for insulated bearings and shaft grounding.
  • Eliminate the need for VFD duty motor insulation and cables.
  • An Active Front End meets IEEE-519 low harmonic requirements & enables “Green”regeneration.

SmartD is a Canadian Company.
Main Manufacturing and Engineering is in Montreal.
Mass production for large projects can be done with our Malaysian facility.

  1. https://primelines-hvac.com/2025/03/tecnicas-y-sistemas-de-refrigeracion-en-centros-de-datos/
  2. https://smartd.tech/your-benefits/energy-efficiency/
  3. https://api.sprecherschuh.com/ecatalog/get/Other/hp-volts-fla_charts.pdf
  4. https://www.greenheck.com/resources/blog/overspeeding-and-underspeeding-fan-motors
  5. https://www.se.com/ca/en/product/ATV630D30S6/variable-speed-drive-altivar-process-atv600-atv630-40hp-600vip20/
  6. https://www.reddit.com/r/ElectricalEngineering/comments/ihg7uz/is_it_okay_to_run_3phase_motor_rated_for_60hz_at/
  7. http://www.50hz60hz.com/60hz-motor-running-on-50hz-power-supply.html
  8. https://www.variablefrequencydrive.net/variable-frequency-drive-for-fans.html

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