Automatic Back EMF DC Shunt Motor Starter 

Automatic Time Delay DC Shunt Motor Starter

Manual Time Delay DC Shunt Motor Starter

Automatic DC Series Motor Starter

Automatic DOL Starter 

Automatic Primary Resistance Starter 

Automatic Auto-transformer Starter 

Automatic Star-Delta Starter 

Automatic DOL Starter 

Automatic Primary Resistance Starter

Automatic Autotransformer Starter

Automatic Star-Delta Starter 

Automatic DOL Starter 

 Automatic Primary Resistance Starter 

Automatic Autotransformer Starter

Automatic Star-Delta Starter 

Automatic DOL Starter

Automatic Primary Resistance Starter 

Automatic Auto-transformer Starter

Automatic Star-Delta Starter 

$\frac{I_2}{I_1}=\frac{R_2}{R_1}=\frac{R_3}{R_2}=\frac{R_4}{R_3}=\frac{R_{n+1}}{R_n}$

$\frac{I_2}{I_1}={\left(\frac{r_a}{R_1}\right)}^{\frac{1}{n}}$

$\frac{I_2}{I_1}={\left(\frac{R_{n+1}}{R_1}\right)}^{\frac{1}{n}}$

All of these 

$r_n=R_n-R_{n+1}$

$r_n={\alpha }^{n-1} r_1$

$r_n=\alpha r_{n-1}$

All of these 

$R_n=r_n+R_{n+1}$

$R_n={\alpha }^{n-1} R_1$

$R_n=\alpha R_{n-1}$

All of these 

$r_n={\alpha }^{n-1} r_1$

$r_n={\gamma }^{n-1} r_1$

$r_n=\alpha r_{n-1}$

All of these 

$R_n=r_n-R_{n+1}$

$R_n={\gamma }^{n-1} R_1$

$R_n=\gamma R_{n-1} - \frac{V}{I_1}\left(\beta -1\right)$

All of these