TO provide a cost-effective method for increasing safety circuit current ratings and enhance their reliability, Rockwell Automation has introduced its Allen-Bradley Bulletin 700S safety control relays.
The 700S relays feature mechanically linked (positively guided) contacts, which are required in feedback circuits for safety applications.
The relays feature mechanically linked double-break contacts that separate the circuit in two spots, enhancing reliability and greatly reducing the possibility of contact welding.
Designed to meet IEC and ANSI requirements, the 700S relay enables contact weld detection of up to 12 poles.
The gap between the double-break contacts is twice that of the typical single-break contact found in most relays. This improves control system reliability and reduces the probability of welded contacts by more than 50 per cent.
The contact configurations are factory-assembled, and permanently fixed front-mount auxiliary contact blocks help prevent field modifications or manual adjustments that can compromise the safety function.
The 700S safety control relays are available in both IEC and NEMA versions: the IEC-compliant 700S-CF, and the NEMA-type 700S-P version--with the 700S-CF version ideal for safety circuits where IEC devices and finger safety terminals are preferred. Rockwell Automation 03 9896 0300.