What is BS EN 61810‑2-1‒ Electromechanical elementary relays about?
BS EN 61810‑2-1 is a part of an international product standard that focuses on electromechanical elementary relays.
BS EN 61810‑2-1 specifies reliability test procedures for electromechanical elementary relays when enhanced requirements for the verification of reliability apply. Particular provisions are given for relays incorporated in safety-related control systems of machinery in accordance with IEC 62061 and ISO 13849-1. It specifies B10 values for dangerous failures (B10D values) are derived from the tests, for such relays.
Note 1: For the calculation of MTTFd for electromechanical relays, the data provided by the manufacturer for B10D can be used.
Who is BS EN 61810‑2-1‒ Electromechanical elementary relays for?
BS EN 61810‑2 on electromechanical elementary relays is useful for:
- Manufactures of electromechanical elementary relays
- Suppliers, dealers, and importers of electromechanical elementary relays
- Installers and service providers for electromechanical elementary relays
- Test houses for relays
Why should you use BS EN 61810‑2-1‒ Electromechanical elementary relays?
When electromechanical elementary relays are incorporated in safety-related control systems of machinery, the meantime to dangerous failure (MTTFd) is taken into account.
BS EN 61810‑2-1 specifies reliability test procedures for electromechanical elementary relays where enhanced requirements for the verification of reliability apply. It gives a type-test that is passed and then confirmed by routine tests with specified periodicity while assessing the probability of dangerous failure.
BS EN 61810‑2-1 describes the significance of figures for B10 (the mean number of cycles until 10% of the relays have failed) that are derived from these life tests performed with representative relay samples. The users can calculate an effective MTTFd value for the relay in a particular application, with the knowledge given in BS EN 61810‑2-1 whenever the safety function of electromechanical elementary relays is concerned.
What’s changed since the last update?
BS EN 61810‑2-1:2017 supersedes BS EN 61810‑2-1:2011, which is withdrawn. This edition includes the following significant technical changes with respect to the previous edition:
- Limitation of tests to 10 M cycles in Clause 5
- Reduction of the required number of test samples to 5 in specified cases
- Introduction of WeiBayes analysis for routine test under Clause 4

