# Chapter 4: Special Purpose Machines¶

## Example 4.1, Page 281¶

In [6]:
#Given data :
P=8;#no. of poles
T=5;#no. of teeteh in each pole
Nr=50.;#no. of teeth in rotor

#Calculations
Ns=P*T;#no. of teeth
Beta=(Nr-Ns)*360/(Nr*Ns);#in degree

#Result
print "Stepping Angle(in degree) : = ",Beta;

Stepping Angle(in degree) : =  1.8


## Example 4.2, Page 282¶

In [3]:
#Given data :
Beta=2.5;#in degree
f=3600;#in PPs
Resolution=360;#in degree

#Calculations&Results
print "Resolution : ",Resolution;
Beta1=Resolution/Beta;#steps/revolution
print "Steps per revolution : ",Beta1;
n=Beta*f/360;#in rps
print "Steps required for making 25 revolution(in rps) : ",n;

Resolution :  360
Steps per revolution :  144.0
Steps required for making 25 revolution(in rps) :  25.0


## Example 4.3, Page 282¶

In [7]:
#Given data :
Beta=15;#in degree
Phase=3;#no. of phase

#Calculations&Results
#Formula : Beta*Nr=(360/phase)
Nr=(360./Phase)/Beta;#unitless
print "No. of rotor :",Nr;
#Case (i) : when Ns>Nr : Formula : Beta=(Ns-Nr)*360/(Ns*Nr)
Ns=Nr/(1-Beta*Nr/360);
print "No. of stator poles if Ns>Nr :",Ns;
#Case (ii) : when Nr>Ns : Formula : Beta=(Nr-Ns)*360/(Ns*Nr)
Ns=Nr/(1+Beta*Nr/360);
print "No. of stator poles if Nr>Ns :",Ns;

No. of rotor : 8.0
No. of stator poles if Ns>Nr : 12.0
No. of stator poles if Nr>Ns : 6.0


## Example 4.4, Page 282¶

In [5]:
#Given data :
Beta=1.8;#in degree
m=4;#no. of phases

#Calculations
#Formula : Beta*Nr=(360/m)
Nr=(360/m)/Beta;#unitless

#Results
print "No. of rotor teeth : = ",Nr;
print "In multi stack motor rotor teeth equals to stator teeth equals to : ",Nr;

No. of rotor teeth : =  50.0
In multi stack motor rotor teeth equals to stator teeth equals to :  50.0