Why umbrella? is it because the high voltage transmission lines are protected against the bad weather by huge umbrellas? No, of course!

In fact this site deals with the way the short circuits are detected on the high voltage  overhead lines. What more simple? You have in your house, as everybody, a circuit breaker which trips thanks to overcurrent detectors if,  when you are tinkering on your electric installation, you make wires touch together, ore if a wire in your washing machine touch the tin, or if you install too many electric apparatuses. We have only to do the same on the high voltage lines. After all, it is always electricity!

Not so simple! Firstly the voltages and currents of the described lines are much higher than in your house: up to 400 000 V and 4 000 A, versus 220 V and 30 A (or a little more if you have an electric heating) in your home. So it is no more possible to make the detectors work with such data, but you must use reducers giving of them an image as accurate as possible, but with a  reduced scale.




Then, as there is in your house only one wire which comes in and another which comes out, on the high voltage lines there are three wires, or three bundles of wires, run by different voltages. More, when in your home the energy comes always from the outside, it may flow here indifferently in one sense ore in another, depending on the mood of the great sorcerers which manage the network. Finally the people who operate the circuit breakers cannot see what happends on the line, and must however avoid accidents

All this leeds to develop some equipment, rather complicated to design, to manufacture, to install and to set. It must even be created, to set a number of them, a program named Umbrella. This is the translation of a french sigle, but I like it as I like to walk under an umbrella when it rains. You not? So each time you see the word Umbrella written, or you see a drawing or a picture with an umbrella, click on it and you will change your opinion.





And this sigle means                                                                                  "Programme d'Aide au Réglage des Appareils de Protections de  Ligne  Utilisant  l'Impédance  Electrique"

(program to help the setting of the line protective relays using electrical impedance) 

This is a program reckoning the setting of equipment situated on each end of the electric energy transmission lines, ...                                                                                                      otherwise, of  the high voltage overhead lines which embellish the landscape of our beautifull country;                                                                                                                these devices make trip the circuit breakers placed on each end of these lines, when a short circuit due to lightning or else, disturb them.


Is this quite clear for you ? Probably not, and that is why I put on this website a book explaining how the disturbances of all kind likely to appear on the french network are cleared  Why the french network? Simply because it is the one I know the best. But each time I could, I noticed how other networks are protected.

(the transmission network is the whole of overhead lines, underground cables and power transformers having in charge the transmission of electrical energy from the power plants to the 20 000 V networks. These assets work at voltages from 63 000 V  to 400 000 V on the french network, and even 730 000 V on other countries, Canada for example)


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If all this does not interess you,  so good bye and thank you for your visit.

If you are interested, here are the documents you will find :

Ì Book" protection and monitoring of the transmission network"               (this document contains among others the presentation of the program umbrella in appendix 8, and its guidebook in appendix 9)

Ì Program Umbrella

If you want more explanations, contact me at:



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If you do not find the further documentation, send me a mail to the address, with your own post address. I shall send you a CD with the whole documentation.


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