Editing Residual-current device (section)

===Type (types of leakage current detected)===
IEC Standard 60755 (''General requirements for residual current operated protective devices'') defines the following types of RCD depending on the waveforms and frequency of the fault current:<ref>{{cite book |title=BS 7671 - Requirements For Electrical Installations |edition=18th:2018+A2:2022 |publisher=[[Institution_of_Engineering_and_Technology|IET]] |pages=156–157}}</ref>
;'''Type AC''' [[file:Typ AC-Symbol.png|40px|RCD type AC symbol]]: These trip on alternating sinusoidal residual current, suddenly applied or smoothly increasing.
;'''Type A''' [[file:Typ A-Symbol.png|40px|RCD type A symbol]]: These trip on both alternating sinusoidal residual current and residual pulsating direct current, suddenly applied or smoothly increasing.
;'''Type F''' [[file:Typ A-Symbol.png|40px|RCD type F symbol part 1]]&nbsp;[[file:Typ F-Symbol.png|40px|RCD type F symbol part 2]]: These trip in the same conditions as Type A, and additionally:
:* For composite residual currents, whether suddenly applied or slowly rising, intended for circuit supplied between {{Not a typo|line}} and neutral, or {{Not a typo|line}} and earthed middle conductor;
:* For residual pulsating direct currents superimposed on smooth direct current.
;'''Type B''' [[file:Typ A-Symbol.png|40px|RCD type B symbol part 1]]&nbsp;[[file:Typ F-Symbol.png|40px|RCD type B symbol part 2]]&nbsp;[[file:Typ B-Symbol.png|40px|RCD type B symbol part 3]]: These trip in the same conditions as Type F, and additionally:
:* For residual sinusoidal alternating currents up to 1{{nbsp}}kHz;
:* For residual alternating currents superimposed on a smooth direct current;
:* For residual pulsating direct currents superimposed on a smooth direct current;
:* For residual pulsating rectified direct current which results from two or more phases; 
:* For residual smooth direct currents, whether suddenly applied or slowly increased, independent of polarity.

The [[BEAMA]] RCD Handbook notes that types F and B have been introduced because some designs of types AC and A can be disabled if a DC current is present that saturates the core of the detector.<ref>BEAMA RCD Handbook - Guide to the Selection and Application of RCDs</ref>