Enter the voltage across the string (volts), the number of discs, and the voltage across the disc nearest to the conductor (volts) into the calculator to determine the String Efficiency. 

String Efficiency Formula

The following formula is used to calculate the String Efficiency.

SE = Vs / (D*VD)
  • Where SE is the String Efficiency
  • Vs is the voltage across the string (volts) 
  • #D is the number of discs 
  • VD is the voltage across the disc nearest to the conductor (volts) 

To calculate the string efficiency, divide the voltage across the string, by the product of the number of discs and the voltage across the disc nearest to the conductor.

How to Calculate String Efficiency?

The following example problems outline how to calculate String Efficiency.

Example Problem #1

  1. First, determine the voltage across the string (volts). In this example, the voltage across the string (volts) is determined to be 59 .
  2. Next, determine the number of discs. For this problem, the number of discs is measured to be 59 .
  3. Next, determine the voltage across the disc nearest to the conductor (volts). In this case, the voltage across the disc nearest to the conductor (volts) is found to be 4.
  4. Finally, calculate the String Efficiency using the formula above: 

SE = Vs / (#D*VD)

Inserting the values from above and solving the equation yields: 

SE = 59 / (59*4) = .25

Example Problem #2

Using the same method as above, determine the variables required by the equation. For this example problem, these are:

voltage across the string (volts) = 934

number of discs = 49

voltage across the disc nearest to the conductor (volts) = 30

Enter these given values into the calculator or above yields: 

SE = 934 / (49*30) = .63