Guessing power line voltage from the number of disc insulator

In general, probably not.

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25KV Low Voltage Silicone Rubber Composite Tension Suspension Electric Insulator for Railway

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Low Voltage 220kV Polymer Composite Power Line Insulator

Images are from http://www.tjskl.org.cn/images/cz154fccb-pz2297256-66kv_polymer_composite_tension_suspension_transmission_line_insulator.html


In a specific country, with a single supplier of high-voltage transmission tower systems, for a small group of towers built at similar times, the answer may be yes.


Is there a good way to guess the power line voltage based on the number of insulator discs that attach the line to the transmission tower?

We usually use as a rule of thumb for determining the number of porcelain/glass suspension disc insulators: 10kV for each disc (standard 5-1/4' x 10").

For typical system voltages in North America, this would be:
69kV: 4-6 discs; 115kV: 7-9 discs; 138kV: 8-10 discs; 230kV: 12 discs; 345kV: 18 discs; 500kV: 24 discs.

You may check Electric Power Generation, Transmission & Distribution by Grigsby, et al.


Table4-6

See attached Table 4-6 from the USDA-RUS Bulletin 1724e300.