X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 14 Nov 2013 07:32:13 -0500 Message-ID: X-Original-Return-Path: Received: from mail-oa0-f46.google.com ([209.85.219.46] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTPS id 6588746 for lml@lancaironline.net; Wed, 13 Nov 2013 23:56:21 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.219.46; envelope-from=pjdmiller@gmail.com Received: by mail-oa0-f46.google.com with SMTP id m1so1675914oag.33 for ; Wed, 13 Nov 2013 20:55:47 -0800 (PST) X-Received: by 10.60.134.14 with SMTP id pg14mr15837734oeb.66.1384404947467; Wed, 13 Nov 2013 20:55:47 -0800 (PST) X-Original-Return-Path: Received: from [192.168.1.144] ([68.202.59.203]) by mx.google.com with ESMTPSA id j9sm4127238oef.8.2013.11.13.20.55.45 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 13 Nov 2013 20:55:45 -0800 (PST) Subject: Re: [LML] Re: N181AM nose gear collapse References: From: Paul Miller Content-Type: multipart/alternative; boundary=Apple-Mail-6E3433BF-B963-4D0F-B0E8-6FF43E6E780C X-Mailer: iPad Mail (10B146) In-Reply-To: X-Original-Message-Id: X-Original-Date: Wed, 13 Nov 2013 23:55:43 -0500 X-Original-To: Lancair Mailing List Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-6E3433BF-B963-4D0F-B0E8-6FF43E6E780C Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable This link for motor applications. http://m.curtisinstruments.com/circuits/datasheets/?fa=3DProduct&ProdID=3D58= 1 Paul On 2013-11-13, at 23:32, Colyn Case wrote: > Paul, got some links for those? >=20 > On Nov 13, 2013, at 1:29 PM, Paul Miller wrote: >=20 > Colyn and others: why aren't we using a simple off-the-shelf motor control= lers like those used in power chairs, golf carts, forklifts and other safety= -minded devices? They handle hundreds of amps, reversible, employ logic to= prevent accidental reversal, work with voltages 12-48, programmable, log di= agnostics and come already packaged in a heatsink and there are no contactor= s to worry about. I see them selling for a few hundred dollars. What bugs= me about Adam's incident is that he had a switch in the down position and t= he pump ran in the UP direction. We certainly have cheap access to the tec= hnology to prevent that from happening to someone else. The scooter and fo= rklift people can't afford to have someone go backwards when they press forw= ard on the lever and this appears to be a mature area of motor control these= days but we don't employ it. Such a device would dump all the relays as I u= nderstand it. On the Curtis models I reviewed, external contactors like th= e one that failed on Adam's plane are still optional but the controller curr= ent is reduced to Zero before the Contactor engages or disengages. I'm not= seeing any downside and since the Oildyne pump is not a high amperage devic= e (compared to a forklift) I believe a solid state controller can be directl= y connected to the Parker pump without the relays (solenoids). >=20 > What am I missing? >=20 > Paul > Legacy >=20 >=20 >=20 >=20 > On 13 November 2013 09:43, Colyn Case wrote: >> A lot of contactors are not really up to it. Some things to look at in t= he specs: >> - for Adam's application, life expectancy vs. break current. See "resis= tive load performance" on the attached ev100 data-sheet or "estimated make/b= reak power switching ratings" on the attached ev200 data-sheet. >> - max break current. If you have a short somewhere you will have large c= urrent. Odyssey batteries can develop over 1000 amps for example. You woul= d like to be able to interrupt that current by de-energizing the contactor (= e.g. turning off a master switch or pump switch) Max break would be about t= he current associated with 5 cycles in the above charts. You may have anl'= s everywhere designed to handle a dead short from anything to anything withi= n one bus. However, there's no anl appropriate for a starter so you are r= eally counting on the contactor to open that circuit if you need to. Same i= ssue with Adam trying to get his pump to stop. >>=20 >> Other things that might be of interest: >> - hold current. how much it takes to keep the contacts closed once they a= re closed. Nice if this is low if you have an alternator failure and are t= rying to stretch battery life. >> - physical integrity. I think standard issue contactors are made from lo= w grade plastic and stamped sheet metal. It was when mine fell apart becau= se of abuse during installation that I got interested in higher quality part= s. >> - I think there is a discussion on the archive about use of transorb's to= minimize damage of the controlling switches due to field collapse in the co= ntactor coil. >>=20 >> I think if you can even find the related specs on standard issue contacto= rs, you'll find them less than satisfying. (Marv - below attachments should= be ~500KB together) >>=20 >>=20 >>=20 >> On Nov 13, 2013, at 9:04 AM, Adam Molny wrote: >>=20 >> Paul - >> The gear relays are activated by applying a small current to the relay co= il >> terminals. That pulls the main contacts closed against a strong spring. W= hen >> you remove power the spring pulls the main contacts apart. There is a kno= wn >> failure mode where the main contacts weld themselves together. When that >> happens the relay will remain in the "on" state regardless of what the >> pressure switches are doing. >>=20 >> -Adam >> -----Original Message----- >> From: Paul Miller [mailto:pjdmiller@gmail.com] >>=20 >> Adam, I don't understand how this happens unless the pressure switches on= >> the pump aren't shutting down. >>=20 >> Paul >>=20 >>=20 >> -- >> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.ht= ml >>=20 >>=20 >> -- >> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.ht= ml >=20 >=20 --Apple-Mail-6E3433BF-B963-4D0F-B0E8-6FF43E6E780C Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
This link for motor applications.


On 2013-1= 1-13, at 23:32, Colyn Case <co= lyncase@earthlink.net> wrote:

=
Paul, got some links for those?

On Nov 13, 2013, at 1= :29 PM, Paul Miller wrote:

Colyn and others: why aren't we using a simple off-the-shelf mo= tor controllers like those used in power chairs, golf carts, forklifts and o= ther safety-minded devices?   They handle hundreds of amps, reversible,= employ logic to prevent accidental reversal, work with voltages 12-48, prog= rammable, log diagnostics and come already packaged in a heatsink and there a= re no contactors to worry about.  I see them selling for a few hundred d= ollars.   What bugs me about Adam's incident is that he had a switch in= the down position and the pump ran in the UP direction.   We certainly= have cheap access to the technology to prevent that from happening to someo= ne else.   The scooter and forklift people can't afford to have someone= go backwards when they press forward on the lever and this appears to be a m= ature area of motor control these days but we don't employ it.  Such a d= evice would dump all the relays as I understand it.  On the Curtis mode= ls I reviewed,  external contactors like the one that failed on Adam's p= lane are still optional but the controller current is reduced to Zero before= the Contactor engages or disengages.   I'm not seeing any downside and= since the Oildyne pump is not a high amperage device (compared to a forklif= t) I believe a solid state controller can be directly connected to the Parke= r pump without the relays (solenoids).

What am I missing?

Paul
Legacy




On 13 November 2013 09:43, Co= lyn Case <colyncase@earthlink.net> wrote:
A lot of contactors are not really up to it. &= nbsp;Some things to look at in the specs:
- for Adam's application, life expectancy vs. break current.   See "res= istive load performance" on the attached ev100 data-sheet or "estimated make= /break power switching ratings" on the attached ev200 data-sheet.
- max break current.   If you have a short somewhere you will have larg= e current.  Odyssey batteries can develop over 1000 amps for example. &= nbsp;You would like to be able to interrupt that current by de-energizing th= e contactor (e.g. turning off a master switch or pump switch)   Max bre= ak would be about the current associated with 5 cycles in the above charts. &= nbsp; You may have anl's everywhere designed to handle a dead short from any= thing to anything within one  bus.   However, there's no anl appro= priate for a starter so you are really counting on the contactor to open tha= t circuit if you need to.  Same issue with Adam trying to get his pump t= o stop.

Other things that might be of interest:
- hold current.  how much it takes to keep the contacts closed once the= y are closed.   Nice if this is low if you have an alternator failure a= nd are trying to stretch battery life.
- physical integrity.  I think standard issue contactors are made from l= ow grade plastic and stamped sheet metal.   It was when mine fell apart= because of abuse during installation that I got interested in higher qualit= y parts.
- I think there is a discussion on the archive about use of transorb's to mi= nimize damage of the controlling switches due to field collapse in the conta= ctor coil.

I think if you can even find the related specs on standard issue contactors,= you'll find them less than satisfying.  (Marv - below attachments shou= ld be ~500KB together)



On Nov 13, 2013, at 9:04 AM, Adam Molny wrote:

Paul -
The gear relays are activated by applying a small current to the relay coil<= br> terminals. That pulls the main contacts closed against a strong spring. When=
you remove power the spring pulls the main contacts apart. There is a known<= br> failure mode where the main contacts weld themselves together. When that
= happens the relay will remain in the "on" state regardless of what the
pressure switches are doing.

-Adam
-----Original Message-----
From: Paul Miller [mailto:pjdmiller@g= mail.com]

Adam, I don't understand how this happens unless the pressure switches on the pump aren't shutting down.

Paul


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