classic | mobile
 

Search...

SA Instrumentation & Control Buyers' Guide

 

SAIMC: Durban branch
November 2017, SAIMC


Tony Rayner, Trabtech product manager, delivered an interesting and comprehensive presentation on surge protection at the Durban branch September technology evening, discussing Lightning Electromagnetic Pulse (LEMP) due, of course, to lightning(!) and Switching Electromagnetic Pulse (SEMP) surges, due to power utility switching, inductive loads (eg motors), defective electrical devices etc.

Hennie Prinsloo (left) thanking Tony Rayner after his presentation.
Hennie Prinsloo (left) thanking Tony Rayner after his presentation.

He emphasised the key principle that surge protection is not the same as voltage regulation – surge protection devices (SPD) - cover short durations from micro second to pico second.

Lightning formation is now well understood – violent updrafts and downdrafts in storm clouds result in the separation of positively and negatively charged ice particles which can create voltage differences between cloud base and ground of as much as 100 million volts. This potential difference causes ionisation of the air and formation of plasma paths which are a precursor to the lightning strikes. Some interesting characteristics of lightning are: voltages between 108 V and 109 V; currents of 300 kA to 800 kA; core temperatures of the plasma at 300 000°C; strike speed of 150 000 km/sec!

He showed some interesting photographs and video footage of lightning formation and strikes to ground, including blowing a wheel off a 737 jetliner(!), damaged masonry and a destroyed wind turbine. Also a humorous video of a lady’s jersey igniting the fuel filler of her car through static electricity discharge!

He moved on to how we can protect our electrical and electronic devices. Three surge protection device classes are defined from two characteristic waveforms – an 8/20 microsecond (rise/duration) waveform falling under IEC Classes I and II, and a 10/350 waveform falling under IEC Class I.

• SPD Class 1 (for lightning protection and usually installed at the main incomer level: technology is typically a spark gap such as gas discharge tube).

• SPD Class 2 (for switching protection and usually installed at the main DB level: technology is typically a metal oxide varistor).

• SPD Class 3 (for device protection and usually installed at the device: technologies are typically varistor and avalanche diode).

It is generally recommended for best protection to use a combined Class 1 and Class 2 SPD arrangement.

Tony’s parting shot: “Protection against lightning is not a dark art. Reputable manufacturers are effectively able to protect against lightning and surges.”

Thanks Tony for supporting the Durban branch and delivering a most interesting talk.


Credit(s)
Supplied By: SAIMC
Tel: 086 107 2462
Fax: 086 651 5238
Email: admin@saimc.co.za
www: www.saimc.co.za
Share via email     Share via LinkedIn   Print this page

Further reading:

  • SAIMC: From the President’s desk
    December 2017, SAIMC, SAIMC
    Time to hand over the reins It is with mixed feelings that I write this, my last letter to you as SAIMC president. It is with sadness because, with the support of council, I have really enjoyed the privilege ...
  • SAIMC: Johannesburg branch
    December 2017, SAIMC, SAIMC
    At the last Technology Evening, Kenneth McPherson, managing director Beckhoff Automation South Africa, presented on EtherCAT. EtherCAT, which stands for Ethernet for Control Automation Technology, is ...
  • SAIMC: Richards Bay
    December 2017, SAIMC, SAIMC
    A well-attended technology evening sponsored by Pepperl+Fuchs was held on Thursday, 5 October at Umhambi Lodge, where the solutions manager responsible for the EPE product range, Frederik Langenhoven, ...
  • SAIMC: SAIMC supporting FIRST Robotics South Africa
    December 2017, SAIMC
    The SAIMC is now proudly supporting FIRST Robotics in South Africa. As a member of the SAIMC, you are invited to attend these robotics events and be part of an initiative where children learn by building ...
  • SAIMC: Tshwane branch
    December 2017, SAIMC, SAIMC
    For the last Technology Evening of 2017, the branch was honoured to have Rob MacKenzie, MD of Endress+Hauser and vice president of the SAIMC, on his birthday, present to a full house about the Industrial ...
  • SAIMC: Durban branch
    December 2017, SAIMC, SAIMC
    The Durban branch of the SAIMC held their November technology meeting as always at the Durban Country Club. The topic was ‘Assessment of the Credibility of Process Alarms as a Layer of Protection’ and ...
  • SAIMC: Cape Town branch
    December 2017, SAIMC, SAIMC
    Relaunch A sense of anticipation came over me the day I volunteered to travel to Cape Town to ensure a free and fair AGM is being held and that a new management team is selected for the Cape Town branch. ...
  • SAIMC: SAIMC Secunda branch Ladies High Tea
    December 2017, SAIMC, SAIMC
    The Secunda branch held its annual high tea for women in the technical field, on Friday 13 October. Despite the very ‘unlucky’ date the event was a great success. This year we strived to involve more ...
  • SAIMC: Secunda branch October Technology Evening
    December 2017, SAIMC, SAIMC
    On Thursday 12 October, the SAIMC Secunda branch held its ninth Technology Evening for 2017 at Honeywell Hub in Secunda. PJ Truter, from Sasol, presented on the topic ‘Vibration Based Condition Monitoring’. ...
  • SAIMC: From the President's desk
    November 2017, SAIMC, SAIMC
    ‘Education-to-employment’ a conundrum in South Africa Over the years, while at the desk of the SAIMC leadership, some observations, beliefs and perceptions surfaced. These however, must be tested with ...
  • SAIMC: Johannesburg branch
    November 2017, SAIMC, SAIMC
    The last Technology Evening was hosted by Endress+Hauser where Dhiren Naidoo, product manager level and pressure, presented on Heartbeat Technology. This presentation covered different diagnostic, verification ...
  • SAIMC: Tshwane branch
    November 2017, SAIMC, SAIMC
    Technology Evenings For the September Technology Evening, Jaco Marneweck from the National Regulator for Compulsory Specification (NRCS), presented to us on the subject of ‘Legal requirements for custody ...

 
 
         
Contact:
Technews Publishing (Pty) Ltd
1st Floor, Stabilitas House
265 Kent Ave, Randburg, 2194
South Africa
Publications by Technews
Dataweek Electronics & Communications Technology
Electronic Buyers Guide (EBG)

Hi-Tech Security Solutions
Hi-Tech Security Business Directory

Motion Control in Southern Africa
Motion Control Buyers’ Guide (MCBG)

South African Instrumentation & Control
South African Instrumentation & Control Buyers’ Guide (IBG)
Other
Terms & conditions of use, including privacy policy
PAIA Manual





 

         
    classic | mobile

Copyright © Technews Publishing (Pty) Ltd. All rights reserved.