---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 04/08/11: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:34 AM - Re: Duel engines gauges (Robert L. Nuckolls, III) 2. 08:51 AM - Re: Contactors (Robert L. Nuckolls, III) 3. 10:03 AM - Re: Contactors (Richard E. Tasker) 4. 10:51 AM - Re: Contactors (Robert L. Nuckolls, III) 5. 04:19 PM - Re: Duel engines gauges (JOHN TIPTON) ________________________________ Message 1 _____________________________________ Time: 06:34:58 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Duel engines gauges At 04:58 PM 4/7/2011, you wrote: >Hi > >If I use a duel CHT gauge and a duel EGT gauge (i.e. both are two >needle instruments), would properly configured 'double pole >changeover' switch work, to monitor the front 2 cylinders , or the >rear 2 cylinders I presume we're talking about thermocouple instruments. You can do as you've proposed. Just make sure each thermocouple pathway gets the same 'pollution' of parasitic thermocouples so that their effects cancel each other. Review chapter on temperature measurement in the 'Connection. Bob . . . ________________________________ Message 2 _____________________________________ Time: 08:51:32 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Contactors At 11:38 PM 4/7/2011, you wrote: > > >Unless I am mistaken the S701 can CARRY the starting current but is >not designed to make or break (close or open) with the high starting >current. The S702 is specifically designed to make or break with >the high starting current. Right on . . . The S701 draws just under 1A of current, is designed for continuous duty operations and is rated to SWITCH only 70A. It has relatively large area, lower pressure contacts. http://www.aeroelectric.com/Pictures/Contactors/S701-1b.jpg The S702 draws 3-5A, gets destructively hot if you leave it on too long and is rated to SWITCH hundreds of amps. It features low area, high pressure contacts http://www.aeroelectric.com/Pictures/Contactors/S702-1a.jpg They are entirely different breeds of cat crafted for specific applications. Having said all that, know that a contactor, relay or switch that is CONTROLLING currents many times the rated value WILL perform to some level. In fact, you may well achieve 'satisfactory performance' from an S701-style contactor in a starter control application. It's service life would be reduced to maybe 1-10% of rated . . . but if that number is still 500-1000 cranking events . . . how might it matter to you? Bottom line is that using the S701 in this manner is simply not the-best-we-know-how-to-do with components having similar costs. Further, it is not a recipe for disaster or even severe spikes in cost-of-ownership. So if you're willing to experiment, then let us know how it works out. Bob . . . ________________________________ Message 3 _____________________________________ Time: 10:03:38 AM PST US From: "Richard E. Tasker" Subject: Re: AeroElectric-List: Contactors While I have no experience using one as a starter contactor, I think I might be concerned that the S701 contacts could end up welded together if the return spring is not heavy enough (depending on the particular starter and engine combination). Dick Tasker Robert L. Nuckolls, III wrote: > > > At 11:38 PM 4/7/2011, you wrote: >> >> >> Unless I am mistaken the S701 can CARRY the starting current but is >> not designed to make or break (close or open) with the high starting >> current. The S702 is specifically designed to make or break with the >> high starting current. > > Right on . . . The S701 draws just under 1A of > current, is designed for continuous duty operations > and is rated to SWITCH only 70A. It has relatively > large area, lower pressure contacts. > > http://www.aeroelectric.com/Pictures/Contactors/S701-1b.jpg > > > The S702 draws 3-5A, gets destructively hot if you > leave it on too long and is rated to SWITCH hundreds > of amps. It features low area, high pressure contacts > > http://www.aeroelectric.com/Pictures/Contactors/S702-1a.jpg > > They are entirely different breeds of cat crafted > for specific applications. > > Having said all that, know that a contactor, relay or > switch that is CONTROLLING currents many times the rated > value WILL perform to some level. In fact, you may > well achieve 'satisfactory performance' from an S701-style > contactor in a starter control application. It's service > life would be reduced to maybe 1-10% of rated . . . but > if that number is still 500-1000 cranking events . . . > how might it matter to you? > > Bottom line is that using the S701 in this manner is > simply not the-best-we-know-how-to-do with components > having similar costs. Further, it is not a recipe for > disaster or even severe spikes in cost-of-ownership. So > if you're willing to experiment, then let us know how > it works out. > > > Bob . . . > > -- Please Note: No trees were destroyed in the sending of this message. We do concede, however, that a significant number of electrons may have been temporarily inconvenienced. -- ________________________________ Message 4 _____________________________________ Time: 10:51:50 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Contactors At 12:58 PM 4/8/2011, you wrote: > > >While I have no experience using one as a starter contactor, I think >I might be concerned that the S701 contacts could end up welded >together if the return spring is not heavy enough (depending on the >particular starter and engine combination). A perceptive concern sir! Bob . . . ________________________________ Message 5 _____________________________________ Time: 04:19:56 PM PST US From: "JOHN TIPTON" Subject: Re: AeroElectric-List: Duel engines gauges Bob Thank you John ----- Original Message ----- From: Robert L. Nuckolls, III To: aeroelectric-list@matronics.com Sent: Friday, April 08, 2011 1:29 PM Subject: Re: AeroElectric-List: Duel engines gauges At 04:58 PM 4/7/2011, you wrote: Hi If I use a duel CHT gauge and a duel EGT gauge (i.e. both are two needle instruments), would properly configured 'double pole changeover' switch work, to monitor the front 2 cylinders , or the rear 2 cylinders I presume we're talking about thermocouple instruments. You can do as you've proposed. Just make sure each thermocouple pathway gets the same 'pollution' of parasitic thermocouples so that their effects cancel each other. Review chapter on temperature measurement in the 'Connection. Bob . . . ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.