In case of sf6 gas leakage in the current transformer below the safe limit value, what happen to the current transformer?
Tarak

The SF-6 gas used in current transformers perform two functions. One is electrical insulation, the second is cooling. Loss of the SF-6 gas also means that the CT is open to the atmosphere and may be incurring moisture and air infiltration. Since most SF-6 gas insulated CTs are high voltage devices, 200 kV to 745 kV, going below the safe limits means the risk of a short circuit of the primary lead to ground. As mentioned above you may also experience CT failure do to loss of cooling. Hope this helps.

I thought they came with built in safety mechanisms. Some valve that if the pressure isn't maintained, or there is current leak then it shuts off.

Never mind, I read the question wrong. To add something more constructive... don't forget how SF6 is used as arc preventative, not only because of its insulating qualities but because of its reactivity. A leak without shut down could fry the whole unit.