# Chapter 2 : Transmission Line Structures and Equipment¶

## Example 2.1 Page No : 77¶

In [1]:
import math

# GIVEN DATA
t_s = 0.49 ; # Human body is in contact with 60 Hz power for 0.49 sec
r = 100 ; # Resistivity of soil based on IEEE std 80-2000

# CALCULATIONS
# For case (a)
v_touch50 = 0.116*(1000+1.5*r)/math.sqrt(t_s) ; # Maximum allowable touch voltage for 50 kg body weight in volts

# For case (b)
v_step50  = 0.116*(1000+6*r)/math.sqrt(t_s) ; # Maximum allowable step voltage for 50 kg body weight in volts
# Above Equations of case (a) & (b) applicable if no protective surface layer is used

# For metal to metal contact below equation holds good . Hence resistivity is zero
r_1 = 0 ; # Resistivity is zero

# For case (c)
v_mm_touch50 = 0.116*(1000)/math.sqrt(t_s) ; # Maximum allowable touch voltage for 50 kg body weight in volts for metal to metal contact

# For case (d)
v_mm_touch70 = 0.157*(1000)/math.sqrt(t_s) ; # Maximum allowable touch voltage for 70 kg body weight in volts for metal to metal contact

# DISPLAY RESULTS
print " a) Tolerable Touch potential , V_touch50 = %.f V , for 50 kg body weight "%(v_touch50) ;
print " b) Tolerable Step potential , V_step50 = %.f V , for 50 kg body weight "%(v_step50) ;
print " c) Tolerable Touch Voltage for metal-to-metal contact , V_mm_touch50 = %.1f V , for 50 kg body weight "%(v_mm_touch50) ;
print " d) Tolerable Touch Voltage for metal-to-metal contact , V_mm_touch70 = %.1f V , for 70 kg body weight "%(v_mm_touch70) ;

 a) Tolerable Touch potential , V_touch50 = 191 V , for 50 kg body weight
b) Tolerable Step potential , V_step50 = 265 V , for 50 kg body weight
c) Tolerable Touch Voltage for metal-to-metal contact , V_mm_touch50 = 165.7 V , for 50 kg body weight
d) Tolerable Touch Voltage for metal-to-metal contact , V_mm_touch70 = 224.3 V , for 70 kg body weight