November 2018

 
November 2018

LIGHTNING SEASON IS UPON US

It is summer again and that means storm season. Southern Africa has an incredible number of lightning strikes, with each ground strike normally approximating one billion volts and 30,000 amps.

With weighbridges being vulnerable to lightning, and lightning is so common in our region of the world, one would have thought that the scale and weighing industry would have sound and consistent approaches to this critical installation issue, but after surveying the multitude of approaches used to protecting weighbridges from lightning, this is plainly not the case.

To be clear there are three “electrical protection issues” to consider with a weighbridge installation and these are:

(1) protection from 220V AC current power surges caused by poor quality electrical supply,

(2) weighbridge grounding and

(3) weighbridge lightning protection.

Sasco lightning protection

The African summer is upon us. 

It is not possible to protect a weighbridge from the consequences of a direct lightning strike on the deck. Thankfully such strikes are rare and the more common effects of lightning are close proximity ground strikes and close proximity cloud-to-cloud strikes capable of producing a significant EMP pulse. 

Close proximity strikes and cloud-to-cloud strikes can be effectively protected against and Sasco achieves this, either at the time of installation or as a retrofit, by doing the following:

  • Installing, into the ground or concrete, thick copper wire around both the perimeter of the weighbridge deck and weighbridge cabin. This cable is brought back to a single ground earth point;

  • Installing an appropriate surge protection device on the communications cable between the indicator and junction box, 

  • Installing an appropriate surge protection device on any external communications cable coming into the indicator; and

  • Finally, installing an appropriate surge protection device on the AC power supply to the weighbridge cabin which must be located inside the weighbridge cabin Faraday cage.

  • Installing copper wire that bonds the weighbridges deck, junction box and loadcell earth strap (shunt) to the single point ground.

Contact us if you are in doubt as to your lightning protection status.

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For further information on the above, contact info@sascoafrica.com or call +27 11 746 6000.

 
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