Proteus 63 AMP 2 POLE 30 mA 2 MODULE RCD 63/2/30T

Product Information

Industrial installations using uninterruptible power supplies (UPS) and variable speed drive (VSD) frequency inverters for the speed control of motors. Some test instruments have a variable trip current setting, if a tripping current of 50 mA at five times I Δn was selected on the Type A setting, a trip current of 350 mA could be simulated (50 x 5 x 1.4 = 350 mA). However, the variable test current feature is not available on all test instruments.

RCDs are far more sensitive than circuit-breakers. The sensitivity being rated in milliamps (mA) as opposed to amps (A). Different Types of RCD NOTE 5: Some typical fault currents in circuits comprising semiconductors are given in Annex A53, Figure A53.1.” What are the effects of DC residual fault current on RCDs? When the Type A setting is selected on the instrument, a half wave pulsating residual test current superimposed on a smooth direct current of 6 mA is produced, which effectively applies a 1.4 multiplier to the rated residual current (I Δn). For example, if the 30 mA setting is selected, the RCD will be subjected to a test current of 42 mA (30 x 1.4 = 42 mA).

What are the different characteristics of the Type A setting on the test instrument?

Further information on RCD operating and non-operating times can be found in the relevant product standards. Type A and Type AC RCCBs and RCBOs are manufactured to BS EN 61008 and BS EN 61009 respectively, whereas Type F and Type B RCCBs and RCBOs are manufactured to BS EN 62423. If you think you may have a faulty RCD, firstly ensure there are no factors within the installation that are influencing the results. Always carry out RCD testing in accordance with industry guidance and manufacturer’s instructions.

It is important to understand that RCDs cannot limit voltage or current, they provide protection by limiting the time a specific maximum current can flow to earth. Many of the issues encountered when testing RCDs are down to user error as opposed to faulty RCDs. It may come as a surprise to some, but RCD testing should be carried out at the RCD with the outgoing wiring disconnected. However, this is not usually done. The usual live working procedures must be considered, and suitable precautions taken when carrying out work near live parts. Sub Committee A of JPEL/64 scrutinized the product standards for RCDs and noted the complexity of testing parameters, as well as the results permitted by the standards that could be used to prove the functionality of an RCD when bench tested in a laboratory.Some equipment will have DC leakage current by the nature of design, other equipment may produce DC currents during fault conditions, dictated by the construction of the equipment. BS EN 61008-1:2012+A12:2017 Residual current operated circuit-breakers without integral overcurrent protection for household and similar uses (RCCBs). General rules. BS EN 62423:2012+A11:2021 Type F and type B residual current operated circuit-breakers with and without integral overcurrent protection for household and similar uses. The early style Residual Current Devices (RCDs) were highly effective protective devices but they have proven to be less reliable in modern buildings as a consequence of DC leakage and DC fault currents caused by electronic equipment. Subsequently, new types of RCD have been developed.

If equipment contains Power Electronic Converter Systems (PECS), more commonly known as inverters or VSDs, BS 62477-1 Safety requirements for power electronic converter systems and equipment sets out the requirements and Annex H provides guidelines for RCD compatibility. Manufacturers must define the safety requirements clearly for suitable RCDs. If this information cannot be obtained, a Type B RCD should be installed to cover the worst-case scenario. It was therefore agreed that the testing procedure could be greatly simplified and safety would remain unaffected since RCDs are, in any event, tested extensively by manufacturers prior to sale. What are the changes to the requirements for RCD testing? Domestic properties with modern equipment and appliances, such as LED lighting, induction hobs, IT equipment and electric vehicle charging equipment.

What is the expected endurance of an RCD?

To help explain, it might be worth thinking about some older models of earth fault loop impedance testers, which could cause the RCD to operate unintentionally. To prevent this, some types of earth fault loop impedance testers imposed a DC current on the AC test current. This DC current saturated the magnetic core of the RCD preventing it from tripping under the test condition. Where electric vehicle charging equipment is likely to create a residual DC fault current, manufacturers may provide the correct type of RCD within the charging equipment. However, problems could arise if the charging equipment is installed downstream of an existing Type AC RCD, which could be blinded by the residual DC fault current. In some types of DC charging equipment, the AC input side is galvanically isolated from the DC output which, hence, provides electrical separation. This means that faults on the DC output side, connected to the vehicle, would not be detected by an RCD on the input side of the circuit. What are the hazards and problems?

It is essential to understand the limitations of the test instrument and product standard requirements when testing RCDs using the available RCD Type settings on the test instrument. Before we look at testing RCDs, it is worth pointing out that the requirements for selection and erection of RCDs have been amended. Regulation 531.3.3 of BS 7671:2018+A2:2022 states that the appropriate RCD shall be selected according to the presence of DC components and AC frequencies. Further, Type AC RCDs shall only be used to serve fixed equipment, where it is known that the load current contains no DC components. Similarly, for instruments with a setting for Type B RCDs a multiplier of two times I Δn is applied as required by the product standard, BS EN 62423:2012 Type F and type B residual current operated circuit-breakers with and without integral overcurrent protection for household and similar uses. NOTE 1: For RCD Type A, tripping is achieved for residual pulsating direct currents superimposed on a smooth direct Type A RCDs are used for alternating sinusoidal residual current and for residual pulsating direct current up to 6 mA.Commercial installations comprising LED lighting and large quantities of IT equipment which can also cause other issues, such as protective conductor current which should also be considered. For further information on the different RCD Types and the selection process, see IET Wiring Matters article (Issue 77 September 2019), ‘Which RCD Type?’