[AMRadio] Fw: Reduce relay contact arc

[JAMES HANLON]

________________________________
From: JAMES HANLON <knjhanlon at msn.com>
Sent: Wednesday, June 13, 2018 6:00 PM
To: CL in NC; aradio at mailman.qth.net
Subject: Re: [AMRadio] Reduce relay contact arc


Charlie,


As I recall, there are relay contact materials that are better at switching AC arcing loads.  Silver cadmium oxide comes to mind.  Mouser stocks a bunch of relays with AgCdO contacts that are rated to switch many amperes at up to 240 volts AC or more.  Do a search on "Silver Cadmium Oxide (AgCdO) General Purpose Relays | Mouser" and you should find a whole bunch of them.


Once upon a time (1970 to 1989), I used to work in a group at Bell Labs that designed relays built by Western Electric and identified good commercial relays for purchase and use in Bell System equipment.


73,


Jim Hanlon, W8KGI


________________________________
From: CL in NC <mjcal77 at yahoo.com>
Sent: Wednesday, June 13, 2018 8:08 AM
To: amradio at mailman.qth.net
Subject: [AMRadio] Reduce relay contact arc

If you have a relay that is switching line voltage or higher AC voltage, is there any way to reduce the arcing?  You might suggest a snubber, but if you use the snubber formula to calculate component sizes, the capacitor allows enough AC to pass such that your transformer is making volts.  You put it on the primary of say a HV B+ PS, and you will get some amount of B+ on the secondary, and if you put it in the secondary HV line, you will leak AC into the rectifiers and still make B+.  Any solutions other that something like a .01 across the contacts and live with it?

Charlie, W4MEC in NC