Chapter 14 , Electronics Instruments

Example 14.1 , Page Number 516

In [2]:
#Variables

Im = 50.0 * 10**-6                     #Full scale deflection current (in Ampere) 
Rm = 1.0 * 10**3                       #Instrument resistance (in ohm)
I = 1.0                                #Total current to be measured (in Ampere)

#Calculation

RS = Rm/(1/Im - 1)                     #Resistance of ammeter shunt required (in ohm)

#Result

print "Value of shunt resistance required for the instrument : ",round(RS,7),"ohm."

Value of shunt resistance required for the instrument :  0.0500025 ohm.

Example 14.2 , Page Number 518

In [4]:
#Variables

Im = 1.0 * 10**-3                      #Full scale deflection current (in Ampere) 
Rm = 1.0 * 10**2                       #Instrument resistance (in ohm)
V = 100.0                              #Voltage to be measured (in volts)

#Calculation

R = V/Im - Rm                          #Required series resistance (in ohm) 

#Result

print "Required series resistance ",R,"ohm."

Required series resistance  99900.0 ohm.

Example 14.3 , Page Number 528

In [8]:
#Variables

num = 3.0                   #Number of full digits on display

#Calculation

R = 1/10**num               #Resolution
V1 = 1 * R                  #Resolution for full scale of range 1 V (in volts) 
V10 = 10 * R                #Resolution for full scale of range 10 V (in volts)
dig = 5.0 * 1/10**3         #Least significant digit
toterror = 0.5/100 * 2 + dig #total possible error (in volts)

#Result

print "Resolution for full scale of range 1 V :",V1,"V."
print "Resolution for full scale of range 10 V : ",V10,"V."
print "Total possible error : ",round(toterror,3),"V."

Resolution for full scale of range 1 V : 0.001 V.
Resolution for full scale of range 10 V :  0.01 V.
Total possible error :  0.015 V.

Example 14.4 , Page Number 528

In [9]:
#Variables

num = 4.0                   #Number of full digits on display

#Calculation

R = 1/10**num               #Resolution
V1 = 1 * R                  #Resolution for full scale of range 1 V (in volts) 
V10 = 10 * R                #Resolution for full scale of range 10 V (in volts)

#Result

print "Resolution of 1 V range is ",V1,"V.\nAny reading upto 4th decimal can be displayed.\nHence 0.5243 will be displayed as 0.5243."
print "Resolution of 10 V range is ",V10,"V.\nAny reading upto 3rd decimal can be displayed.\nHence 0.5243 will be displayed as 0.524 instead of 0.5243."

Resolution of 1 V range is  0.0001 V.
Any reading upto 4th decimal can be displayed.
Hence 0.5243 will be displayed as 0.5243.
Resolution of 10 V range is  0.001 V.
Any reading upto 3rd decimal can be displayed.
Hence 0.5243 will be displayed as 0.524 instead of 0.5243.