Posted on 20th Dec 2023

Darwin Motion Variable Frequency Drive (VFD) is a type of motor controller that adjusts the frequency and voltage supplied to an electric motor, allowing for energy savings by controlling the motor speed. The energy savings achieved with a VFD depend on factors such as the application, motor load, and operating conditions.

To estimate energy savings using a VFD, you can use the following general steps and formula:

**Determine the Motor Power (P_motor):**

Identify the power rating of the motor in kilowatts (kW). This information is usually provided on the motor nameplate.

**Determine the Motor Efficiency (?_motor):**

Find the motor efficiency from the motor documentation or nameplate. It is usually given as a percentage.

**Determine the Motor Load Factor (LF):**

The Motor Load Factor is the ratio of the actual load on the motor to its full load capacity. It is expressed as a decimal. For example, if the motor is running at half of its full load capacity, the load factor would be 0.5.

**Calculate the Full Load Power (FLP):**

FLP = P_motor / ?_motor

**Calculate the Energy Consumption without VFD:**

Energy_without_VFD = FLP * LF * Time

**Determine the Speed Reduction Factor (SRF):**

The speed reduction factor is the ratio of the initial speed to the reduced speed when the VFD is applied.

**Calculate the Energy Consumption with VFD:**

Energy_with_VFD = FLP * LF * (1 / SRF) * Time

**Calculate Energy Savings:**

Energy_Savings = Energy_without_VFD - Energy_with_VFD

**Here's a simplified example using these steps:**

Let's say you have a 10 kW motor with 90% efficiency, running at half load (LF = 0.5) for 1,000 hours.

P_motor = 10 kW

?_motor = 90%

LF = 0.5

FLP = 10 kW / 0.9 = 11.11 kW

Energy_without_VFD = 11.11 kW * 0.5 * 1,000 hours = 5,555 kWh

Now, let's assume the VFD reduces the speed by 20% (SRF = 0.8).

SRF = 0.8

Energy_with_VFD = 11.11 kW * 0.5 * (1 / 0.8) * 1,000 hours = 6,944 kWh

Energy_Savings = 5,555 kWh - 6,944 kWh = -1,389 kWh

In this example, the energy savings would be 1,389 kWh with the VFD. Note that actual savings may vary based on specific operating conditions and the characteristics of the motor and load.

Darwin Motion offers Micro Drive- Matrix 900, DR Matrix 350 / Solar Drive, High Frequency Drive - DR Matrix 500, High Performance Drive - DR Matrix 680, Regenerative Drive - DR Matrix 880