High voltage protection

Hi.

I am on a new project for Gas Stations to check if the Tankers have good earth before un loading fuels to the station.

My concern is about the protection of the electronics, especially the PIC®.

The design will check for more than 10 ohms resistance in the loop. So inputs of the circuit will be exposed. I think of adding a device like the one in the attached pdf from the inputs to ground.

A Tanker may have up to 200KVolt before grounding. Will a device like TRANSZORB® help to protect my circuit?

Ioannis

I had worked on an almost identical product, for the very same application. Except the requirement was to detect resistances of more than 2 ohms.

Mine was a very simple device based around a 12F675, using its ADC. I wasnt aware of the static buildup on the tanker being of that magnitude at all. Perhaps it also has to do with the geographical location you are in? I thought the few volts of static would get grounded when the cable gets connected. Or maybe I need to recall all units...

But if it really goes up that high, shouldnt you also worry about discharging it at one go? I mean, it would be much safer to dissipate it slowly, wouldnt it?

Regards,

Anand

The www.newson-gale.co.uk company has a lot of infos about the case.

Now, my next step was to measure the resistance of the earth. Newson-Gale turn off the fuel valves when this resistance is more than 10ohms.

I would be greatfull for any infos you can share on your project.

Ioannis