Hi Prior. You wrote: < A client uses PONZ-1 relays in a safety circuit for packaging machinery. This circuit has been approved by US & EU agencies. He would like to change to EE Controls positive guided relays. The circuit would be re-evaluated with the EE Controls type SH0! 4 positive guided relays. His questions is "what are the chances of these EE Control relays being approved?" He does not want to present the circuit to an agency for evaluation without some assurance that these relays are acceptable.>
US approval and EU approval may well be in relation to quite different things. PNOZ relays enable Guard and Emergency stop circuits to comply with the EU Machinery Directive safety requirements, but id they comply with a US agency, this is probably not related to the very high integrity guarding requirements of the EC, but more to do with UL approvals. (fire and electric shock protection) I don't know the EE Controls relay, but if you are evaluating these for interlocked guarding systems you should not only consider the 'guided contact' attribute, but also the 'dual redundency' attribute that will cause the system to be safe in the event of a single fault. PNOZ relays have a dual input which provides this level of protection, many simple guided contact relays do not. A two cents worth, maybe... Chris Dupres Surrey, UK.
