Electrical installation & energy efficiency

This is a very interesting comment because you give me the opportunity to clarify the end of life mode of SPD (including MOVs and gas tube):
Let me explain two cases.
A surge arrester can happen at the end of life in the following cases:
a) by thermal runaway due to an accumulation of excessive constraints of not exceeding its lightning
attributes, leading to a slow destruction of its internal components.
The disconnection of the SPD is provided by a thermal fuse associated with the electronic components (MOVs) inside the SPD
b) by short-circuit due to exceeding the maximum flow capacity or due to a fault under 50hz from the electrical distribution network (neutral rupture ,…). The disconnection of the SPD is provided by an external or integrated short circuit protection device like fuse or circuit breaker.

Considering the short circuit protection device(b), why choose circuit breaker instead of fuse?
● Choose the rating must consider both surge withstand and low short circuit breaking capability
● Compare to fuses, CBs have good compromise between surge withstand and low short circuit breaking capability
*The same rating CB has better surge withstand capability than fuse
*The lower rating CB has better short circuit breaking capability

For instance, SPD with following characteristics : In=5kA, Up=1,3kV is coordinated with its short circuit protection device:
* circuit breaker C curve 20A
* or fuse 22x58 63A

The information you include about SPD´s iwill mislead the opinion of
engineers

because there´re manufacturers that had consider the problem and
include a fuse in front
of each MOV, designed to open the circuit in case of a failure or end of life of the varistor.

but it´s not any fuse, because it goes in the protection module in front of each MOV. On the other hand a limiting fuse for protection will jeopardize the function of the SPD

Hello,

Nice article. I think to avoid the fire of a building we will use the “external” lightning protection system such as lightning conductor or meshed cage. Thanks for sharing all the useful information with me. Keep it up.

Hello, tree-phase protection at the building entrance (using heavy discharge tubes made by TTI Puerto Rico) has solved most problems in Venezuela. However there is a ever growing problem present, probably world-wide. The problem is as follows:

Most computer users buy "stabilyzers" using MOV type surge protectors. These are single-phase devices and see what the happens doring a lighning storm: when surge arrives, the sinle phase MOV will cut the overvoltage surge to a save level for the computer it is ment to protect. But now the catastrophic effect is because the power clippling at one phase rises very dangerously spikes at athe other two phases at the whole building. I have seen a chane of PC failures that did not have MOV protection.

This effect should be communidated to all computer-users !

The real solution is really a building-entrance protection, while the individual MOV protection at the consumer load is too danderous !

Please comment your experience ! Rehards Hans Stauffer, Caracas Venezuela (stauffer@cantv.net)

Iwould say you have to install a 3 phase protector at the service entrance to avoid this problem.

I would like to ask if someone have made measurements of the shape of the wave at the service entrance in any distribution system of any electrical utility co.in any city or country.
I´m curious to learn if a SPD should include EMI/RFI noise filtering or if a SINE WAVE TRACKING WILL BE ENOUGH in order to supply a clean signal to the utility customers.

thanks for your help,

GERARDO TAMA

hi
could you help me for finding INDELECT software for finding the best place for installing prevectron?

Hi

Isn't the surge protective philosophie concerning T2 arresters described in Wiki-EIG a little bit old -fashioned?

http://www.electrical-installa…..Type_2_SPD

I understand that it is coming from the time when France had own standard which knew only todays T2 arresters and they were suggested to be choosen concerning by risk of lightning (and by more valuable equipment).

Today, when international standard uses 'german' (my term) approach - T1, T2, T3 arresters – I do not see the reason  to split T2 arresters (which are mainly varistors) into so many different levels.  The Up of smaller varistors is mainly lower only for the reason that Up is always measured by In, so by the same surge current the actual  Ures is the same , or by same cases – more powerful arresters have even lower Ures thah the smaller ones.

 There is not significant price difference either (at least on our market) between T2 arresters having  Imax 40, 20, 15 , or 5 kA.

T2 arresters having Imax 65 kA are today sold under label  T1+2  with Iimp =7kA

Price depends more from how famous is the brand name of the producer or of his activity on the market.

I find that there is enough to have one standard T2 arrester  40/20kA  and in the last end  to use T3 arrester.

Btw. If I read the definition  of  the "Lighting  Protection Zones" in  EN 62 305 , than I understand, that LPZ 3 requires defenitely screening of the zone. So – it means that there is no sense to install T3 arrester into distribution board if the device to be protected is located not in the same DB but  situated somewhere in distance and feeded via normal PVC cable without screen?

(of course – installation T3 there makes not the situation worse)

PS

What You as specialists think about so called 'T1+2'  arresters, which itself are only a little bit more powerful varistors.

Is their effect really comparable with devices where  2  physically different devices (spark gap and varistor) are mounted beside each other (sometimes on the same base only, sometimes into the same housing)?  

Hi..
Thanks for info thats you give…this relay helf me…