Relays with Forcibly Guided Contacts

What do we not see as we go about our day-to-day travels that helps keep us safe? From automatic gates or elevator lifts to cranes and metro railcar doors, what are the controls behind the scenes?

Same situation in factories or warehouses. Conveyors to move finished goods or shipments, machine presses used to stamp parts, recycling systems, scissor lifts and many other applications. The controls behind all this work to keep you safe.

One small but important item often found in these controls are relays. Not your everyday typical relay but relays with forcibly guided contacts. What’s the difference?

Contacts.

Relays have a set of contacts, typically normally open (NO) and normally closed (NC), that move energy dictated by an input to the coil. In a normal relay the group of contacts are independent of each other.

Once energized, the (NO) contact closes while the (NC) contact opens and vice versa. If one contact fails, ‘welds’ together, it cannot separate, the potential exists that the other contact would continue to switch. In a safety application this failure is not at all desirable.

The construction of a force guided relay pays close attention to these contact sets. A barrier or mechanism is engineered around the contacts physically linking all contacts together. If a contact were to weld due to this construction the opposing contact set would not mate as they are interlinked. Other precautions like contact spacing, reliability tests and approvals are also undertaken increasing performance and safety values.

Both Finder’s 48 and 7S Series interface modules offer application solutions when relays with forcibly guided contacts are needed.

Entry into the force guided relay interface modules is with the 48.12 in screw or push-in termination. According to EN 61810-3 Type B (only 1 NO + 1 NC) this module offers 8 A rating gold contacts and either a 12 or 24 V DC coil.

Find out more on the Type 48.12 product page.

SIL 2 (PL d)

The 7S.23 is a compact 17.5 mm module with screw termination providing a 3 pole (2 NO + 1 NC) configuration. Contact rating is up to 10 A. Available in 12, 24, 48, or 110 V DC coils.

This group of 7S modules offer a variety of contact configurations and either screw or screw-less termination. DC coils in 12, 24, or 110 V. AC coils in 120 or 230 V. The 22.5 mm package offers standard gold contacts in certain versions.

SIL 3 (PL e)

The 7S.43/63 enhances the construction with double channel architecture (1oo2) consisting of 2 NO safety contacts, 1 NC feedback contact and 1 auxiliary signaling contact. With 12, 24, 48, or 110 V DC coils, a 6 A (3 A DC13) contact rating, and screw or screw-less termination.

Find out more on the 7S Series product page.