The vehicle shall not interfere with the existing signalling systems that are present in the track system. This applies both to separate SDUs and to multiple-coupled units.The vehicle shall be so designed that it prevents any occurrence of “phantom balises”, i.e. EMC interference which the onboard system interprets as the passing of a balise. It shall do so regardless of the cause of the interference, which might, for instance, be the opening/closing of the main circuit-breaker or frost on the contact wire.The delivery shall comply with EN 50121 (Railway applications – Electromagnetic compatibility).The delivery shall comply with EN 62311 (Assessment of electronic and electrical equipment related to human exposure restrictions for electromagnetic fields (0 Hz – 300 GHz)), for the parts relevant according to EN 50500 (Measurement procedures of magnetic field levels generated by electronic and electrical apparatus in the railway environment with respect to human exposure).For uncertainty regarding the risks of electromagnetic fields, the precautionary principle (ADI 477, Arbetsmiljöverket/Swedish Work Environment Authority) shall apply.2.2.4.1.3 EMC for systems