IEC 61051-2-2021 pdf free download – Varistors for use in electronic equipment – Part 2: Sectional specification for surge suppression varistors.
When the configuration is other than described above，the detail specification shall statesuch dimensional information as will adequately describe the varistor. When the varistoris not designed for use on printed boards，this shall be clearly stated in the detailspecification.
7.3Mounting
The detail specification shall specify the method of mounting to be applied for normal use andfor the application of the vibration and the bump or shock tests. The varistors shall be mountedby their normal means.The design of the varistor may be such that special mounting fixturesare required in its use. In this case, the detail specification shall describe the mounting fixturesand they shall be used in the application of the vibration and bump or shock tests. For the lattertests, the mounting shall be such that there shall be no parasitic vibration.
7.4Ratings and characteristics
The ratings and characteristics shall be in accordance with the relevant clauses of thisspecification.
7.5 Marking
IEC 61051-1:2018,4.3 applies.
The detail specification shall specify the content of the marking on the varistor and on thepackage.
7.6Ordering information
The detail specification shall specify the ordering information.
When coding is used, the method shall be preferably selected from those given in lEC 60062.
8Quality assessment procedure
8.1 General
IEC 61051-1:2018,Clause 5 applies.
8.2Primary stage of manufacturer
The primary stage of manufacture is defined as the initial mixing process of ingredients.
8.3Structurally similar components
IEC 61051-1:2018,5.4 applies.
Varistors within the scope of this specification may be grouped as structurally similar for thepurpose of forming inspection lots provided that the following requirements are met:
a) They shall be produced by one manufacturer on one site using essentially the same design,materials, processes and methods;
b) For electrical tests,devices having the same electrical characteristics may be grouped
provided that the element determining the characteristics is similar for all the devicesconcerned;
c)For environmental tests,devices having the same encapsulation, basic internal structure
and finishing processes may be grouped;
d) For visual inspection (except marking) devices may be grouped if they have been made on
the same production line, have the same dimensions encapsulation and external finish;
The grouping may also be used for robustness of terminations and soldering tests where itis convenient to group devices with different internal structures (see item c) above);
e) For endurance tests，devices may be grouped if they have been made with the same
production process in the same location using the same design and differing only inelectrical characteristics. lf it can be shown that one type from the group is more heavilystressed than the others, then tests on this type may be accepted for the remaining membersof the group.
8.4Qualification approval (QA)8.4.1Qualification approval (QA) procedures
The procedures for qualification approval testing are given in the Generic Specification,IEC61051-1:2018，5.5.
The schedule to be used for qualification approval testing on the basis of lot-by-lot and periodictesting is given in 8.5 of this document.
The procedure using a fixed sample size schedule is given in 8.4.2 and 8.4.3.8.4.2Fixed sample size procedure
The fixed sample size procedure is described in lEC 61051-1:2018,5.5.3 b).
The sample shall be representative of the range of values for which the approval is sought to.This may or may not be the complete range covered by the detail specification.The proportionof specimens having the different characteristics shall be proposed by the manufacturer’s chiefinspector and shall be to the satisfaction of the national supervising inspectorate.
When additional groups are introduced into the qualification approval test schedule, the numberof specimens required for Group “o” shall be increased by the same number as that requiredfor the additional groups.
8.4.3Test schedule
The complete series of tests specified in Table 4 are required for the approval of varistorscovered by one detail specification.The tests of each group shall be carried out in the givenorder.
The whole sample shall be subjected to the tests of Group “0” and the divided for the othergroups.For insulated varistors, the tests of Group 1 shall be made before the tests of Groups to 7.
Specimens found defective during the tests of Group “0” shall not be used for the other groups.IEC 61051-2 pdf  download.