Which electric motor do I need? Find the right electric motor in 5 steps.
You need to replace your electric motor and want to know which electric motor you need. It is not always easy to find the correct replacement motor. You might need to replace an older model that is obsolete or discontinued. To help you, we will explain in 5 steps how to choose the right electric motor in the ABF webshop.
In this blog, we assume a 3-phase motor, as this is the most commonly used type of electric motor. In many cases, all the information can be obtained from the nameplate on the motor.
Below, you will find an example of a nameplate for an older generation of a Siemens electric motor. You can use this information to check for yourself whether a similar product is available in our webshop.
Which electric motor do I need?
STEP 1: Determine nominal power
The nominal power of an electric motor is normally expressed in kilowatts (kW). On older motors, the power may also be expressed in horsepower (hp). The conversion is: 1HP = 0,75kW.
The power of an electric motor is based on the maximum power for a constant load. In this example, the electric motor has a nominal power of 1.5kW (or 2HP).
- B3: Foot only
- B5: Outer flange (flange diameter exceeds that of the motor)
- B14: Inner flange (flange diameter is smaller than that of the motor)
- B35: Foot mounted + outer flange (combination of B3 and B5)
- B34: Foot mounted + inner flange (combination of B3 and B14)
The design can often be read from the nameplate. However, it can also be determined using the drawings below.
- A (distance between mounting holes, perpendicular to motor)
- B (distance between mounting holes, parallel to motor)
- C (shoulder of shaft to the first mounting hole)
- D (diameter of output shaft at drive end – D.E.)
- E (Shaft length)
- H (Shaft height)
For electric motors adhering to IEC Standards, most dimensions are directly related to the Shaft Height, or Frame Size of the motor. This is the distance between the centre of the output shaft and the centre and bottom of the feet of a B3-style motor, as indicated in the diagram below by the letter “H”.
- IE1 = standard efficiency (EFF2)
- IE2 = high efficiency (EFF1)
- IE3 = premium efficiency
- IE4 = super premium efficiency
Since 1 January 2017, all new electric motors with a power rating of 0.75kW or above must meet the IE3 standard (however, there are exceptions to this rule).
The electric motor in our example has an energy efficiency of IE1. In order to meet current regulations, select IE3 in our webshop (view in webshop).
The right electric motor?
In our webshop, we have now selected the following filters:
- Nominal power: 1.5kW
- Mounting B14 (inner flange) and B34 (foot + inner flange)
- Nominal speed: 2 poles / 3000 rpm
- IEC frame size: 90
- Energy efficiency: IE3 = premium
You should now have found the correct electric motor. The selection of motors shown should meet the specifications of the electric motor you are trying to replace (view in webshop).
When comparing the nameplates of the old, and the replacement motor, it is clear that the specifications match. Please note, this particular motor is of mounting “B34” but is fitted with detachable feet and inner flange (an option Siemens provides).
Siemens nameplate
The following image shows an explanation of a Siemens nameplate. Please note that this image refers to a “standard” Siemens motor. Non-standard Siemens motors, or motors with certain extra options are denoted with the addition of “-Z” at the end of the Article Number.
In the examples used above, the “-Z” stands for the option of detachable feet on a B34 motor.
Hopefully, by following these 5 easy steps, you will find the right electric motor in the webshop. However, if you have further questions, please do not hesitate to contact the electric motors specialist for more advice on the matter.
This blog is brought to you in cooperation with ABF. For more blogs, please visit www.abf.store/blog