## Selection Criteria For every application determine the TORQUE and MAXIMUM RPM. Example Selection Criteria

 Metric English Line Tension (T) 8N 1.8 lb Full Spool Radius (r) .15m 5.9 in Spool Core Diameter (d) .125m .41 ft Line Speed 90 m/min 295 ft/min

Step 1Calculate Maximum Torque
The line tension multiplied by the radius of a
full spool.

Example:
Full Spool Radius (r) x Line tension (T)= Torque
.15m x 8N =1.2Nm or 5.9 in x 1.8 lb= 10.6 lb-in

Selection: In this example select Model EB-140 or larger.

Step 2 Calculate MAX RPM
When a magnetic brake shaft is turning, mechanical energy is converted into thermal energy (watts). The amount of thermal energy (watts) is a function of RPM and TORQUE.

 Example Max = Line Speed______ = 90m/min___ =295 ft/min__ =229 RPM Calculation: RPM   3.14x Core Dia (d) 3.14 x .125m 3.14 x .41 ft

Step 3 Calculate Power Dissipation

 Example Calculation: P (watts) = T(lb-in) x RPM = 1.2 x 229 = 29 watts 9.55 9.55
 Example Calculation: P (watts) = T(lb-in) x RPM = 10.6 x 229 = 29 watts 84.36 84.36

Selection: In this example P=29 watts. The Model EB-140 is rated for 75 watts continuous and 500 watts for 5 minutes.

Step 4Determine Operating Current
From the product data sheets examine the Performance Curve to determine the approximate operating current.

Solution: In this example the EB-140 Performance Curve is shown below. Our previously determined 1.2Nm, requires a maximum current of 270mA @ 24VDC. Typically the brakes have a 15-35% safety factor, so that the actual current will be 230mA (from the chart below) 