Construction of low voltage plants – Part 530: Selection and erection of electrical operating equipment – switching and control device
The new version of these installation regulations was published in June 2018. It is a complete reworking and amendment of the previous version from June 2011.
The numbering of a few paragraphs and annexes differs from the previous version. It includes requirements for the selection of isolation and switching devices that were previously published separately (1).
Here is a summary of the amendments regarding the use of residual current operated protective devices (RCDs).
Type F RCDs have been included for the detection of rated frequency sinusoidal AC and pulsating DC residual currents and AC residual currents with mixed frequencies (2).
There is a table and 13 diagrams containing information on which RCDs are suitable for which types of load and residual currents (3). Four new diagrams have also been added since the previous version and are highlighted in grey to make them quicker to find. They depict switches with frequency converters which should only be operated with Type F or B RCDs, or only with type B. We have made the diagrams below available to you in PDF format. In order to improve understanding and for the sake of completeness, we have also added the variant ‘single-phase without rectification’. This very simple, classic fault is not specified in the standard. Diagrams 2–14 correspond to the 13 diagrams in the standard.
The use of type AC RCDs is generally not permitted in Germany for new installations. Type B+ RCDs can be used as an alternative to type B RCDs (4).
In order to avoid unintended switch-off of RCDs due to operational leakage currents in protective cover systems, these leakage currents should be set to a maximum of 0.3 times the rated residual current (5). In the previous version DIN VDE 0100-530, 0.4 times the rated residual current was permitted. It is also recommended that the circuits to be protected are distributed across multiple RCDs.
There is now also a detailed description of how RCDs should be selected depending on who has access to the electrical system. In systems that are accessible to lay-persons, children or disabled people, only type A residual current circuit-breakers (RCCBs) (6), type A residual current operated circuit-breakers with integral overcurrent protection (RCBOs) (7) or type F or B RCCBs/RCBOs (8) should be used (9). In systems to which only trained electricians have access, circuit-breakers with residual current trip (CBRs) and type A or B residual current devices (10) can also be used. The various protective devices along with their functions and product standards are listed in table 536.1.
Unfortunately, the instructions for operation-relevant switching are extremely confusing. On the one hand they state that protective devices (which include RCDs) should not be used for operation-relevant switching (11). On the other hand however, they claim that RCCBs and RCBOs are suitable for operation-relevant switching (12) but advise that “the device is not recommended for frequent operation-relevant switching.” What is meant by this is that, for example, a residual current circuit-breaker (RCCB) can be used as a breaker for emergency switch equipment (13). In this context, ‘operation-relevant’ means: A residual current circuit-breaker is switched in the event of an emergency stop or an isolation class fault. Residual current circuit-breakers are not, however, suitable for the day-to-day on and off switching of electrical circuits or individual consumers. Emergency stop devices must be suitable for isolation (14).
Automatic restart of protective devices is permitted in systems to which only trained electricians have access (15). According to local and national guidelines, however, devices with automatic restart should be used for retention of power supply in areas to which lay-persons, children or disabled people have access, only if certain evaluation criteria for restart are met.
The benefits at a glance
1 previously: DIN VDE 0100-537
2 Section 531.3.3: This section specifies the different types of RCD in correspondence with the types of residual current to be detected.
3 Annex A, p. 53–55
4 Annex A, p. 55, note 2
5 Section 531.3.2
6 as per DIN EN 61008-1
7 as per DIN EN 61009-1
8 as per DIN EN 62423
9 Section 531.3.4
10 as per DIN EN 60947-2
11 Section 530.4.5
12 Annex B in table B1
13 as per section 537.3.3
14 Section 5188.8.131.52 and table B1 in annex B
15 Section 531.1
Head of Standardisation/Certification