How to Select Your Brushless DC Motor

Selection Criteria

Motor type

For the new Ultra EC series, Portescap offers 3 different types of brushless DC motors, identified by B for the slotted series (high torque, high speed, autoclavable option), BH for the slotless series (high speed, high efficiency), and EC (for Electronically Commutated).

This product line is offered with various options: S (high-speed optimization), T (high-torque optimization,) and H (medium torque and speed), directly linked to the needs of your applications.

Motor size

Typically the best place to start when sizing a brushless DC motor is matching motor size (diameter, length). Diameter ranges from 13 mm to 30 mm. Brushless DC slotted motor diameter and length are specified in inches. Brushless DC slotless motor diameter is specified in milimeters, and length as a coding (S, M, L, ...). Ultra EC Series motor diameter and length are specified in milimeters.


Various winding options are proposed to best match with the application requirements – voltage, resistance and torque constant are the basic parameters for selection.


Generally with three winding phases, brushless DC motors are electronically commutated. A simple way to drive these motors is to power two phases at a time, using hall sensors to know the rotor position, with a simple logic to allow optimal energizing of the phases as a function of rotor position. Another way is to use sensorless electronics, working with the zero-crossing criteria to determine rotor position and commutation cycle. This electronics format is well suited for constant speed applications as they are highly insensitive to hostile environments.

 Brushless DC Slotted
 B 05 08 NO24A R 00 05 R
 B  B = Brushless DC
 05  Diameter (in)
 08  Stack length
 NO24A  Winding
 R Motor shaft option
R = Round
0 = Gearhead
 00 Type
00 = Motor only
0G = Gearhead
 05 Gearbox ratio
Ex: 05 = 5:1
 R Gearhead shaft
R = Round
 Brushless DC Slotless
 22 BH M 8B P 1
 22  Diameter (mm)
 BH  Brushless DC
 M Body length
S, C = Short
M = Medium
L = Long
F = Flat
 8B 8B = Hall sensor, 8 wires
3C = Sensorless, 3 wires
6A = On-board electronic, 6 wires
2A = On-board electronic, 2 wires
P Winding
 1 Execution coding
 Ultra EC Series
 22 EC S 45 10B 24 1
 22  Diameter (mm)
 EC  Brushless DC
 S Ultra Platform designation
S = High speed
T = High torque
P = Price-to-performance cost advantage
 45 Length (mm)
10B 10B = hall sensor with thermal sensor, 10 wires
8B = hall sensor, 8 wires
3C = sensorless, 3 wires
 24 Winding
 1  Execution coding