HV Electrical Distribition Lines Protection

How make 15,8KV and Over Voltage HV Electrical Distribition Lines (City int.) Protection ?




Edit:Sorry Under-->Over

Protection from what? Don't think you'd have to worry much about people stealing power, stepping it down to something more useful would be costly, and the should be able to detect the loss (they would need to shut it off to tie into it).

Protection for kids climbing high tension towers... ? I survived, but never went as high as the wires, great view though.

Why would you need undervoltage protection on high voltage transmission lines? THat's the kind of thing that's dealt with at the power plant.

Over Current (and Over Voltage) Protection...

WOuldn't that still be dealt with at the power plant's regulation? All the kinds of overvoltage protection I know cut power off altogether...not the best thing to do if there is a spike in the transmission line...

Gas discharge tubes and spark gaps (e.e. Jacob's ladder are normally used for overvoltage protection.

Hayrettin Demir said:

How make 15,8KV and Over Voltage HV Electrical Distribition Lines (City int.) Protection ?

Edit:Sorry Under-->Over

Click to expand...

There are high voltage fuses designed for that sort of voltages.

And then, of course, automatic breakers that are tripped from the signal received from current transformers.

When I worked on medium voltage (6.6-25kV) gear there was a system which consisted of a copper tube filled with explosive and a circuit that monitored the current. If the rate of rise of the current exceeded a set value then the explosives were detonated. It was used to protect switchgear that could handle the normal 650A but would be destroyed by the 21kA fault current.

BTW, this was about 30 years ago. I,m sure things have progressed since then.

Mike.

Some kids removed the huge nuts at the bottom of high voltage transmission towers a few blocks from my home.
The towers fell down and the wires were across a big busy road. Luckily nobody got zapped.

Pommie,

I experienced one of those "tripping". Was standing at a bus stop when one, on top of a power pole across the street, detonated. So then I'm on the ground, behind the bench. Not too long back from Viet Nam.

Ken

In most cases the voltage regulation is dealt with in the area substations.

In our part of the world we have 66 / 22 kV and 33 / 11 - 6.6 kV area substations which do the voltage regulation and keep the voltage stabilized for the 22, 11 and 6.6 distribution networks.

These area substations are fed from the 33 and 66 kV subtransmission network which are fed from the 110 and 220 kV national grid.

This is done by means of TCOL ( Tap Changers On Load ).
These will step up or down the voltage at the primary side of the substation TX.
The reference voltage is taken of the substation VT (voltage transformer)

The street distribution TX do have also a tapchanger for a local adjustment. These are not designed to switch on load and the TX has to be deenergized before a tap can be altered.

To protect OHUG cables, often lightning arrestors are fitted which clamp excessive short time duration voltage spikes.