Post by thread:[EE] Pinning in newer relays

I was looking at some of the new Tyco/Schrack relays, the T7S series. Anyone know why they've moved one of the N/O pins up to in-between the coil pins. Won't this be dangerous if using mains currents between the N/O pins? Why change it from the original coil pins on one side and N/O pins on the other? Laura --------------------------------- Yahoo! for Good Click here to donate to the Hurricane Katrina relief effort.

I do not know about T7S series but T7N is similar. As long as the creepage distance and clearance fulfill the standards, it is okay to be used. In T7N's case, the common contact pin is put between the coil pins. This is quite unusual but it is still okay (6mm from the center hole of the common pin to the coil pins, normally 5.5mm is required for double insulation and 3mm for basic insulation). It is also okay to be used for UL since it is recognized by UL. It can not be used in Protection Class II equipment though. I am now using Schrack PE014 relay for Protection Class II. It is one of the smallest which fulfill Protection Class II (Overvoltage category III and reinforced insulation, voltage rating 250V according to IEC60664). The isolation voltage between relay coils and contacts need to be greater than 3750V RMS in order to be used in Protection Class II. Maybe one big customer of T7N/T7S series requires Tyco/Scrack to do this. EN50178 and UL508/UL840 are good to read in terms of isolation requirement. It is not so fun to read though. Regards, Xiaofan -----Original Message----- From: laura capaldi Sent: Friday, October 07, 2005 10:28 AM To: spam_OUTpiclistTakeThisOuTmit.edu Subject: [EE] Pinning in newer relays I was looking at some of the new Tyco/Schrack relays, the T7S series. Anyone know why they've moved one of the N/O pins up to in-between the coil pins. Won't this be dangerous if using mains currents between the N/O pins? Why change it from the original coil pins on one side and N/O pins on the other? Laura

At 07:27 PM 10/6/2005 -0700, you wrote: >I was looking at some of the new Tyco/Schrack relays, the T7S series. >Anyone know why they've moved one of the N/O pins up to in-between the >coil pins. Won't this be dangerous if using mains currents between the N/O >pins? Why change it from the original coil pins on one side and N/O pins >on the other? > >Laura I don't see the T7S in a quick search (it's always best to post a link to a data sheet if you have it handy). Assuming it's the same as the other T7 relays, this is an old and (IMHO) electrically inferior construction. I don't like using it for mains relays. Also the coil-to-contact breakdown is seldom as good as 4kV, and I've seen relays with that construction as bad as 500V rating, which makes them unsuitable for anything but toys. It does have a bit better electromagnetic efficiency, so you can get lower power consumption for a given switching current and life compared to other simple relays, but I really don't like using this type for mains switching, even if it meets the minimum requirements for UL. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam@spam@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com ->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff