The standards EN 60204-1 and EN IEC 61439-1
The reference standard for the design and construction of on-board machine panels or at the service of Machinery is:
EN 60204-1: Machinery Safety - Electrical equipment of machines. Part 1: General Requirements.
The standard analyzes the various functions required for the electrical equipment of a machine and provides sizing criteria:
- Disconnection (Cap. 5). Among the main errors is the confusion between the need for an external disconnector and the request for a door lock.
- Protection against Electrical Shock (Cap. 6). Here too there are often errors in the diagrams, also due to the fact that the standard assumes knowledge of the function of TN and TT earthing systems.
- Equipotential Bonding (Cap 8): Here, unfortunately, the standard is written in a too complex way, such that the manufacturer is led to conclude that all the structural parts of the electrical equipment must be earthed.
- Circuits and command and control functions (Cap. 9): grounding downstream of a control transformer is still under discussion.
- Verifications (Cap 18): it is here that verification of the impedance of the fault loop and the suitability of the corresponding overcurrent protection device is explained and required.
However, this is not the only rule applicable to machine switchboards. Unfortunately, EN IEC 61439-1 must also be respected, although for years it has been discussed within the technical committees that this standard contains "too severe" requirements for switchboards that are often built in a single copy.
One of the critical aspects is the Design Verification called "Short-circuit withstand" §10.11. This can be avoided:
a) For SWITCHBOARDS which have short-time rated currents (see 5.3.4), or conditional rated short-circuit currents not exceeding 10 kA rms value (see 5.3.5).
b) For SWITCHBOARDS or SWITCHBOARD circuits protected by current limiting devices having a limited peak current not exceeding 17 kA in correspondence with the maximum presumed short-circuit current allowed at the terminals of the ENCLOSURE input circuit.
c) For the auxiliary circuits of the SWITCHBOARDS intended to be connected to transformers whose rated power does not exceed 10 kVA with a secondary rated voltage that is not less than 110 V, or does not exceed 1.6 kVA with a secondary rated voltage less than 110 V, and whose short-circuit impedance is not less than 4%.
All other circuits must be verified.
We hold training courses on the compliance of the Electrical Equipment with the Current Regulations, as well as carry out consultancy activities.
Read more about the subject, machinery electrical panels products standards EN 60204-1 and EN 61439-2.