How safe are your safety devices

Any one would expect a safety device like SPD- Surge protection Device to “fail safely” in case of any abnormalities above the SPD’s limit. Also, situations like Neutral cut or shift in a power supply system is not un- common. There were few incidences of SPD explosion & ÀUH DFFLGHQWV LQ ,QGLD. 1RZ, PDQXIDFWXUHUV RI 63'V
no longer get away with this problem that, the failure
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addresses this issue apart from all other safety issues.
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need to be tested as per the latest international standard so that the safety is not compromised. When it comes to safety devices, it is all the more important to adhere to latest standards because more & more safety features are getting added to ensure that safety devices- in this case SPDs act & save the electronic equipment & in case of failure due to abnormalities in the incoming supply, VKDOO ´)$,/ 6$)(µ ZLWKRXW FDXVLQJ ÀUH KD]DUGV.
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all testing methods are totally new. SPDs tested as SHU ,(& 61643-1 QHHGV WR XQGHUJR IHZ VDIHW\ WHVWV WR JHW TXDOLÀHG. %HFDXVH, ,(& 61643-1 WDONV RQO\ DERXW
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about “Safety & Performance Tests”.
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all the important safety parameters which are added  

 

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by the customer and  also  enable  them  to  use  more & more safety compliance SPDs to protect their electronic & electrical equipment from lightning and switching surges.

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in the medium and high voltage system.

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of neutral. After this test, either SPD shall withstand this stress of high voltage or “fail safe” without FDXVLQJ ÀUH RU H[SORVLRQ KD]DUGV.

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h Additional tests are added for SPD failure mode simulation.

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each of the above points.

 

TOVs caused by “faults” in the medium and high voltage system

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under “Medium Voltage”

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“High Voltage”.

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safety feature required in SPD.

This can be best understood by the below example.

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power  distribution  systems shall  be tested at a voltage

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&  protective  conductors for  more  details. The revised

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these details, when released.

 

New TOV test parameter of 120 minutes for LV system faults and loss of neutral.

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fault or loss of neutral, either the SPD shall withstand this abnormal condition or “fail safely” without causing H[SORVLRQ RU IDLOXUH. ,W LV REYLRXV WKDW, DQ 63' GHVLJQHG

to withstand this abnormal condition is costlier than the

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decides which one is best suited.

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minutes or “fail safely” after getting stressed to this high YROWDJH OHYHO IRU 120 PLQXWHV. ,Q QHLWKHU FDVH, 63' VKDOO H[SORGH RU FDWFK ÀUH 

Class II Operating Duty Test is made more stringent by applying 15 impulses at

crest value of Open Circuit Voltage of the Combination Wave Generator

This  is  very  simple  parameter  because,  when  SPD

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more on SPDs & they shall withstand these stringent FRQGLWLRQV ZKHQ FRPSDUHG WR PRUH UHOD[HG 10 LPSXOVHV DW SURJUHVVLYH YDOXHV RI RSHQ FLUFXLW YROWDJH DV GHÀQHG LQ ,(& 61643-1. (G 2, 2005.

 

Pass criteria has been increased significantly.

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Additional tests are added for SPD failure mode simulation.

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safety  parameters, following  additional tests are added

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abnormal conditions.

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h     SPD with separate isolated circuit test

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harsh conditions when compared to SPDs tested as per

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SPD manufacturers, who have tested their SPDs as per 

 

 

TABLE- 1: Quick- Comparison Chart

 

 

Sl No.

IEC 61643-1 ed 2 2005 -03

IEC 61643-11 ed 1 2011-03

1

addresses performance test ONLY

addresses safety and performance test

2

talks about AC and DC in the scope

talks only about AC in the scope

 

 

3

normative references have several unwanted standards which are not connected with this subject.

while normative references removes, unwanted standards, it adds IEC 61000 all parts- EMC & IEC 61180 -1 HV test techniques for LV equipment

4

Class II test is for Imax

class II test is for In

 

5

 

12.5 and 25 kA for I impulse is added and charge 6.25 and

12.5 As added

6

 

preferred value of Uc many voltages are added

 

7

 

installation instructions for type of LV system that is TN, TT and IT are added

 

8

 

behavior under TOV caused by faults in MV and HV are added

9

 

EMC is added

10

 

test on terminals are added

 

11

 

metallic screen test setup and use of tissue paper is added in general testing procedure

 

12

preconditioning test is performed to prepare this sample for the test

there is no preconditioning test ; EUT is directly used for the test.

 

 

 

13

class III operating  duty  test  involves  applying a total of 10 impulses BUT @ 10%, 25%, 50%,

75%, 100% of open circuit voltage

 

class III operating duty test involves applying 15 impulses at crest value of open circuit voltage

 

14

Number of pass criteria is much lesser (3 - 4 conditions)

 

pass criteria A-O (15 conditions)

 

15

muslin paper and cheese cloth are used for testing

 

tissue paper and metallic screen are used for testing

 

 

 IEC 61643-1 Ed 2 to test only some extra features so that they comply with IEC 61643-11 Ed. 1. In fact, it is possible that some manufacturers falsely claim that their SPDs have “pass criteria” by testing as per IEC 61643-1, Ed 1, 1998, which is much more dangerous. Because in 1998 edition, Voltage protection level was declared for a spark gap by taking into account the “AVERAGE VALUE” of 10 test impulses. Say, for ex, as per 1998, an SPD would have been declared to have Voltage protection level of 1.2 kV (say) but as per 2011, voltage protection level should be declared as 4 kV (say), because in this case, is the “MAXIMUM VALUE” of 10 test impulses. One small change in the testing procedure has a very high impact on the declared value, which  one should not fail to note. Hence all the users of SPD  shall  ensure that, the SPDs they buy for their requirement complies all the safety & performance test as per IEC 61643-11 so that their installation is safe for both the people and the equipment.

 

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