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Number of Suspension Insulators for a Given Voltage Level 
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#1
Jul413, 10:05 AM

P: 1,089

Hello all,
I'm currently designing all the structure, equipment and grounding for a 230115kV terminal substation, and for our dead end connections consisting porcelain ball & socket type suspension insulators we are given the number of insulators required for each voltage level. (i.e. 14 for 230kV and 9 for 115kV) On what basis do they determine that 'X' number of insulators are needed for a voltage level of 'Y'? Is it the dry arcing distance? Is it the creepage distance? Is it a combination of multiple factors, or does one particular factor mostly dominate over the others? Also I've often heard that there is a rule of thumb through which one can guess at the voltage level of a given transmission line by counting the number of insulators in a given insulator string, is this true? Thanks again! 


#2
Jul413, 10:34 AM

P: 1,803

Forty years ago I worked with an engineer who had worked at a power station. He told me how to estimate the voltage of high tension power lines (in the US). He knew the standard transmission voltages, which I have long forgotten, and it was simply a matter of counting the number of insulators, multiplying by 10kV and "rounding" to the nearest standard voltage. All I still remember is the 10kV per insulator.



#3
Jul413, 08:59 PM

PF Gold
P: 1,881

Here are three manufacturers that give descriptions and specifications of their high voltage insulators:
http://www.ceramicinsulator.com/showproduct.asp?id=80 http://sunelectric.en.alibaba.com/pr...nsulators.html http://electricalengineeringportal...***insulators 


#4
Jul813, 10:19 AM

Sci Advisor
PF Gold
P: 11,900

Number of Suspension Insulators for a Given Voltage Level
I wouldn't make any final choices without asking the manufacturers themselves about this. I imagine you will need this installation checked by some insurance inspector and you'd hate to be told it was not adequate.



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