MT 25 - TC 85/MT 25

IEC 60477-1:2022 applies to resistors intended for use as laboratory DC resistors (hereinafter referred to as "resistors") comprising standard resistors, single or multiple resistors of accuracy Classes 0,000 05 to 10 and single or multi-dial resistors of accuracy Classes 0,000 5 to 10.
This document does not apply to:
1) resistors which are intended for use solely as permanently mounted circuit components,
2) resistors used on alternating current or on pulsed current,
3) active resistors,
4) series resistors and shunts which are considered as accessories of electrical measuring instruments in the relevant IEC document (examples of these are as follows).
IEC 60477-1:2022 cancels and replaces the first edition of IEC 60477 published in 1974, and its Amendment 1:1997. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) extended the resistor accuracy classes;
b) deleted the resistor accuracy class expression in parts per million (ppm);
c) excluded the active resistor from the scope of this document;
d) updated the terms and definitions according to new IEC 60050 series;
e) changed the term "resistance decade" to "resistance dial" to cover the multi-dial resistors with other resistance step values;
f) updated the intrinsic error to intrinsic uncertainty according to IEC 60359;
g) added the limits of relative stability for resistors of classes 0,000 05 to 0,01;
h) added the requirements of high voltage resistors;
i) updated the safety symbols and requirements according to the new IEC 61010 series;
j) updated the insulation resistance requirements of resistors;
k) added the requirements of temperature coefficient;
l) updated the temperature requirements for transport and storage of resistors.

IEC 60477-2:2022 applies to resistors intended as laboratory AC resistors for use over a range of frequencies from DC up to a stated frequency which is not in excess of 1 MHz. Such resistors are hereinafter referred to as "AC resistors".
In addition to satisfying the requirements of IEC 60477-1, resistors satisfying the requirements of this document are designed to have a small variation of resistance and a small phase displacement over the stated frequency range.
IEC 60477-2:2022 cancels and replaces the first edition published in 1979, and Amendment 1:1997. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) extended the AC resistor frequency range to 1 MHz;
b) updated the terms and definitions according to IEC 60050 series;
c) added the definition of AC/DC difference of an AC resistor;
d) added the resistor classification according to the AC resistance or AC/DC difference index;
e) updated the classification according to the AC resistor construction;
f) updated the safety symbols and requirements according to IEC 60477-1;
g) added the three-element equivalent circuits of an AC resistor in Annex C;
h) added the annex on constructions of AC resistors.