Peter, I beg to differ on one point. To some people the difference between a wet contact and a dry contact does imply a difference in switching capability. I didn't make this one up myself. The definition was passed on to me by one of the "old ones" around here. A wet contact would be designed to either minimize or handle the arcing associated with high voltage and/or current. A dry contact would weld together under the same circumstances.
Having said that, I could understand how you could probably have never seen these terms used to characterize the load capability of a relay. This kind of discussion goes over into the wonderful world of jargon. Where words can have many different meanings to many different people. Chris Maxwell Design Engineer Nettest From: [email protected] [mailto:[email protected]] On Behalf Of Peter L. Tarver Sent: Monday, February 23, 2004 3:25 PM To: [email protected] Subject: RE: dry circuit questions Another interpretation of the terms "dry circuits" and "dry contacts" is application related. "Dry circuits" are not "wetted" with a voltage, as analog POTs lines are. A set of contacts in a "dry circuit" might be used to detect an open-circuit -vs- a closed circuit condition, without appreciable current flow in the closed-circuit condition. "Dry contacts," might open or close on a circuit with no appreciable voltage, for instance a set on contacts controlling the grounded side of a circuit or for a ground detection circuit. The terms including "dry" do not contain any notion of the switching capability of a set of contacts. Regards, Peter L. Tarver, PE [email protected] > From: Chris Maxwell > Sent: Monday, February 23, 2004 10:49 AM > > David, > > Dry contact relays are named because of what they > don't have. Many high > current relay designs feature contacts that are > wetted with Mercury in > order to prevent damage from arcing during > make/break cycles. > From: [email protected] [mailto:[email protected]] On Behalf Of Cereceres, David Sent: Monday, February 23, 2004 1:26 PM To: '[email protected]' Subject: dry circuit questions "When you see a reference to either 'dry contact' or 'dry circuit' as far a relay goes, what does this mean the relay is designed to handle?" As always, your guidance is always appreciated. Regards, David Cereceres This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
