Last edit: 27/08/2024
Chapter 18 of the Standards details the verification to be perform by the Manufacturer.
The extent of verification will be given in the dedicated product standard for a particular machine. Where there is no dedicated product standard for the machine, the verifications shall always include the items a), b), c) and h) and may include one or more of the items d) to g):
a) verification that the electrical equipment complies with its technical documentation;
b) verification of continuity of the protective bonding circuit (Test 1 of 18.2.2);
c) in case of fault protection by automatic disconnection of supply, conditions for protection
by automatic disconnection shall be verified according to 18.2;
d) insulation resistance test (see 18.3);
e) voltage test (see 18.4);
f) protection against residual voltage (see 18.5);
g) verification that the relevant requirements of 8.2.6 are met;
h) functional tests (see 18.6).
The continuity test was only meant to verify the connection of “exposed conductive parts” to the protective circuit, which is necessary for the fault loop.
However, the grounding of metal parts is also necessary for the safety of control systems. In the new Version of EN 60204-1:2018, the language is as follows:
9.4.3.1 Insulation faults.
9.4.3.1.1 General
Measures shall be provided to reduce the probability that insulation faults on any control circuit can cause malfunction such as unintentional starting, potentially hazardous motions, or prevent stopping of the machine.
This results in grounding the control transformer common and grounding all metal parts that could affect a control function.
In the next photo there is a Stop button and an Emergency button.
As seen in the next photo, the metal part must be grounded for the safety of the control systems and not because it is an electrical ground.
So even if the control transformer is SELV, the metal enclosure must be connected to the equipotential protection system.
So the continuity test also covers this metal part, although it is not “grounding for protection against indirect contacts.”
The new version of the standard changes the language by requiring a continuity test separate from the verification of protection against indirect contacts, to be applied where necessary, such as in the case of safety of control systems.