X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from elasmtp-mealy.atl.sa.earthlink.net ([209.86.89.69] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6588727 for lml@lancaironline.net; Wed, 13 Nov 2013 23:32:46 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.69; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=ElvIbGHkJprtny1++c1MlybhYwO0oP1Q/H+DzgVk/9KDYOZv64pi40Ftm+g9yGzt; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [70.16.215.180] (helo=[192.168.1.24]) by elasmtp-mealy.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1VgobF-0006rh-6A for lml@lancaironline.net; Wed, 13 Nov 2013 23:32:13 -0500 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: multipart/alternative; boundary=Apple-Mail-24-221923296 Subject: Re: [LML] Re: N181AM nose gear collapse Date: Wed, 13 Nov 2013 23:32:12 -0500 In-Reply-To: To: "Lancair Mailing List" References: Message-Id: X-Mailer: Apple Mail (2.1085) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940adb78b21799030ef7e411d6c86c9162a350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 70.16.215.180 --Apple-Mail-24-221923296 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii 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 motor = controllers 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 diagnostics and come already packaged in a heatsink = and there are no contactors 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 the pump ran in the UP direction. We = certainly have cheap access to the technology to prevent that from = happening to someone 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 mature area of motor control these days but we = don't employ it. Such a device would dump all the relays as I = understand it. On the Curtis models I reviewed, external contactors = like the one that failed on Adam's plane 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 forklift) I believe a solid = state controller can be directly connected to the Parker pump without = the relays (solenoids). What am I missing? Paul Legacy 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 = the specs: - for Adam's application, life expectancy vs. break current. See = "resistive 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 large = current. Odyssey batteries can develop over 1000 amps for example. You = would 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 the 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 within one bus. However, there's no anl = appropriate for a starter so you are really counting on the contactor to = open that circuit if you need to. Same issue with Adam trying to get = his pump to stop. Other things that might be of interest: - hold current. how much it takes to keep the contacts closed once they = are closed. Nice if this is low if you have an alternator failure and = are trying to stretch battery life. - physical integrity. I think standard issue contactors are made from = low grade plastic and stamped sheet metal. It was when mine fell apart = because of abuse during installation that I got interested in higher = quality parts. - 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 contactor 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 should 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 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 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@gmail.com] Adam, I don't understand how this happens unless the pressure switches = on the pump aren't shutting down. Paul -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html -- For archives and unsub = http://mail.lancaironline.net:81/lists/lml/List.html --Apple-Mail-24-221923296 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii 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 = motor controllers 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 diagnostics and come already packaged = in a heatsink and there are no contactors 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 the pump ran = in the UP direction.   We certainly have cheap access to the = technology to prevent that from happening to someone 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 mature = area of motor control these days but we don't employ it.  Such a = device would dump all the relays as I understand it.  On the Curtis = models I reviewed,  external contactors like the one that failed on = Adam's plane 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 forklift) I believe a solid state controller can be = directly connected to the Parker pump without the relays = (solenoids).

What am I = missing?

Paul
Legacy

<= /div>



On 13 November = 2013 09:43, Colyn Case <colyncase@earthlink.net> wrote:
A lot of contactors = are not really up to it.  Some things to look at in the specs:
- for Adam's application, life expectancy vs. break current.   See = "resistive 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 = large current.  Odyssey batteries can develop over 1000 amps for = example.  You would 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 the 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 within one =  bus.   However, there's no anl appropriate for a starter so = you are really counting on the contactor to open that circuit if you = need to.  Same issue with Adam trying to get his pump to stop.

Other things that might be of interest:
- hold current.  how much it takes to keep the contacts closed once = they are closed.   Nice if this is low if you have an alternator = failure and are trying to stretch battery life.
- physical integrity.  I think standard issue contactors are made = from low grade plastic and stamped sheet metal.   It was when mine = fell apart because of abuse during installation that I got interested in = higher quality parts.
- 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 contactor 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 should 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
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
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@gmail.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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