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EARTHING + LIGHTNING PROTECTION
Abbreviations/Acronyms
DB
– Distribution Board
MCR – Measurement, Control and Regulation
SPD
– Surge Protection Device
I
have just finished reading an article about ‘lightning strikes and
surges’. Even though I have been in the industry for many years,
it was difficult to understand and rather boring. In this light, I
have attempted to simplify surge and lightning protection dynamics,
thereby, hopefully, making it easier for prospective users to make an
informed choice when purchasing protection systems. To simplify
my explanation I have divided Surges into two categories, namely
Lightning strikes and Other Surges.
Why do we need protection?
Lightning strikes
Around the world there is lightning activity, some areas minimal,
others moderate, and others extreme. Where ever there is lightning
activity, huge amounts of energy may be induced into electrical reticu-
lation, causing, in many instances, catastrophic damage. To protect
systems against this phenomenon, lightning protection is required.
It is also important to know that lightning protection should always
be used in conjunction with surge protection.
Other surges
Surge (other) protection is another matter. In general surges are
manmade and mostly generated by electrical switching operations.
Examples of these (amongst many others) could be the starting of
inductive loads or power failures. Obviously these transients are pre-
sent 24/7 affecting electrical supplies. Therefore it goes without saying
that surge (other) protection is an imperative. So, even if you are not
situated in a lightning area, surge (other) protection is still necessary.
These extremely fast voltage and current disturbances, including
lightning, which I prefer to call transients, cause hundreds of millions
of Rands worth of damage to equipment every year.
What do we use for protection?
Protection is broken up into three categories, namely:
• Type 1 (Class I) – Coarse protection.
These devices are used for
protection against Lightning Transients. Normally situated in
the primary mains supply DB (Distribution Board) and used in
conjunction with Type 2 devices
Brief guide to the selection of
lightning and surge protection
Tony Rayner, Phoenix Contact South Africa
A basic explanation of what to consider when selecting lightning and surge protection.
OPINION
21
October ‘16
Electricity+Control