Changes between Version 4 and Version 5 of Playbook/Engineering/MotorSelectionPhysics

Timestamp:

Feb 11, 2018, 5:10:01 PM (7 years ago)

Author:

Timothy Lin

Comment:

--

Playbook/Engineering/MotorSelectionPhysics

@@ -1 +1 @@
 = A General Method for Choosing Motors and Gearings
 
-{{{
-#!div style="border:3pt dotted; color:red; text-align:center; font-size:150%"
-Work in Progress
-
-
-}}}
-
-With the plethora of requirements, motors, gearboxes, pulley systems, etc., how do you choose which motor and gearbox(es) to use? How do you know they will
+With the plethora of requirements, motors, gearboxes, pulley systems, etc., how do you choose which motor and gearbox(es) to use? How do you know they will meet your needs? This page provides a very basic guide to what to consider and the process to do so to choose an appropriate motor and gear ratio.
 
 The example/case study below (in the green boxes) are probably more intuitive and easier to follow than the theory presented first in each section, but the theory discusses the why and how.
@@ -354 +347 @@
 That is, breakers won't trip for short peaks.
 
-For each of the motor speeds above, there is an associated current
+These values are represented as datapoints or as a graph in fuse datasheets, like [http://files.andymark.com/MX5SpecSheet.pdf this one for the 40A FRC Circuit Breaker].
+
+For each of the motor speeds above, there is an associated current; our task now is to check the current draw and make sure the breaker won't trip:
+
+
+{{{#!th align=center
+'''Speed at Motor'''
+}}}
+{{{#!th align=center
+'''Current Draw'''\\
+(from Motor Curve)
+}}}
+{{{#!th align=center
+'''Percent of Current Rating'''
+}}}
+{{{#!th align=center
+'''Trip Time for 40A Breaker'''\\
+(from Spec Sheet)
+}}}
+|----------------
+{{{#!td align=center
+10,800 RPM
+}}}
+{{{#!td align=center
+60 A
+}}}
+{{{#!td align=center
+150%
+}}}
+{{{#!td align=center
+3.9-47 s
+}}}
+|----------------
+{{{#!td align=center
+8500 RPM
+}}}
+{{{#!td align=center
+70 A
+}}}
+{{{#!td align=center
+175%
+}}}
+{{{#!td align=center
+2.2-9.2 s
+}}}
+|----------------
+{{{#!td align=center
+5500 RPM
+}}}
+{{{#!td align=center
+90 A
+}}}
+{{{#!td align=center
+225%
+}}}
+{{{#!td align=center
+1-3 s\\
+(interpolated)
+}}}
+|----------------
+
+In this particular situation, we are not going to be pulling that current for more than a second, at most 2 seconds, so we could choose any of the three gearings, but it'd be best to ''not'' choose the 1:60 speed. 1:80 gear ratios and above are your best bet in this situation.
 
 }}}