To keep the transmission line in healthy condition it is utmost essential that all the Strings are in extremely good condition.

To keep the String in extremely good condition we have to ensure that apart from no visible mechanical damages the number of defective insulator should not be more than

• 2 Nos in – For 400 kV
• 2 Nos in – For 220 kV
• 1 No in – For 132 kV
• 1 No in – For 66 kV

The above detection of insulator strings Scanner detection is based on the induction effect.

The Scanner is slid over the insulators at a definite distance. Due to induction across individual insulators the corresponding voltage induced in scanner is monitored.

The graph of such induced voltages of all the insulators will show the health of individual insulator.