X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 01 Dec 2013 09:34:41 -0500 Message-ID: X-Original-Return-Path: Received: from qmta14.westchester.pa.mail.comcast.net ([76.96.59.212] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6619953 for lml@lancaironline.net; Sat, 30 Nov 2013 08:03:50 -0500 Received-SPF: pass receiver=logan.com; client-ip=76.96.59.212; envelope-from=jmorgan1023@comcast.net Received: from omta21.westchester.pa.mail.comcast.net ([76.96.62.72]) by qmta14.westchester.pa.mail.comcast.net with comcast id voyv1m0011ZXKqc5Ep3Gtp; Sat, 30 Nov 2013 13:03:16 +0000 Received: from [192.168.1.103] ([24.11.157.196]) by omta21.westchester.pa.mail.comcast.net with comcast id vp3F1m00Y4EXR5U3hp3GZE; Sat, 30 Nov 2013 13:03:16 +0000 From: Jack Morgan Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: multipart/alternative; boundary="Apple-Mail=_7BAA3F4A-6C9B-4460-911F-21113931BE6B" Subject: Aint electrical fun? X-Original-Date: Sat, 30 Nov 2013 08:03:15 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <1BEF975C-3F64-4901-BD7B-4E14FADAB78B@comcast.net> X-Mailer: Apple Mail (2.1283) --Apple-Mail=_7BAA3F4A-6C9B-4460-911F-21113931BE6B Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 Hi Colyn, It is almost always(almost?) possible to find a more expensive better = sounding component when talking relays and solenoids as well as most = electronics. I am not aware of an unreasonable failure rate with the Lancair = recommended stuff but have obviously not been around the Lancair = community as long as others. The problem with condemning a component = without knowing all the factors leading up to the failure is that = introducing a different component may cloud the real issue or cause a = new one. If a particular aircraft has failed a Lancair suggested relay, = covering up the issue with a more robust relay may lead to a more = serious failure later... or maybe not. Getting the highest reliability = can only be accomplished by getting to the real root cause of each = failure. If there has been a consistent pattern of failure of the Lancair master = solenoids activating the gear pump then I am all in finding the cause = and a different or added component which has been proven in at least = twenty or so installations throughly tested across the four seasons. If = there is no failure pattern then putting in a seemingly better part is = lose-breakeven poker. My vote is to keep the fleet as uniform as possible so real reliability = issues can be isolated. If there is no consistent component usage, = identifying real problems and achieving real quality will be impossible. = Dreaming up fancy designs is fun. Real reliability is very hard to = achieve and much less/no fun. We Americans are an innovative lot. That = is why Japan kicked our butt in the 70's and 80's. Sorry to be a quality zealot but I was part of the problem back then and = learned the hard way along with everyone else. Jack Morgan On Nov 30, 2013, at 6:00 AM, Lancair Mailing List wrote: > From: Colyn Case > Subject: Re: [LML] Motor locked current > Date: November 29, 2013 9:46:41 PM EST > To: "Lancair Mailing List" >=20 >=20 > Jack, I was with you until you got to "The solenoid Lancair = recommends". > See the reply to Giff I just posted where Bob Nuckolls argues to the = contrary. >=20 > On Nov 29, 2013, at 6:53 PM, Jack Morgan wrote: >=20 > Hi John, >=20 > A good rule of thumb on dc motors is 4 to 1 so your measurement seems = good. Your readings are also consistent with the 35 amp breaker which I = understand is typical for the pump. >=20 > Inductive loads like the motor are easiest to turn on for relays since = the contacts are made before the current reaches the locked value. = Incandescent lamps are the worst case turn on load..... 10 to 1 is the = rule of thumb (no kidding) for the inrush into a cold lamp. With only = the inductance of the connecting wires the relay really sees an inrush = while it is making contact in lamp circuits. >=20 > If a normally sized relay were to break with the pump rotor locked it = would be highly stressed, maybe even fail. Most designers rely on the = breaker to trip to protect the wiring, motor, and relay and ignore the = unlikely possibility of the relay being turned off during the short time = it takes the breaker to trip with a locked motor. The solenoid Lancair = recommends is capable of surviving turning off the starter for awhile so = won't be damaged in any case. Nothing like belt and suspenders. >=20 > Jack Morgan >=20 --Apple-Mail=_7BAA3F4A-6C9B-4460-911F-21113931BE6B Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=iso-8859-1 Hi = Colyn,

It is almost always(almost?) possible to find = a more expensive better sounding component when talking relays and = solenoids as well as most electronics.

I am not = aware of an unreasonable failure rate with the Lancair recommended stuff = but have obviously not been around the Lancair community as long as = others. The problem with condemning a component without knowing all the = factors leading up to the failure is that introducing a different = component may cloud the real issue or cause a new one. If a particular = aircraft has failed a Lancair suggested relay, covering up the issue = with a more robust relay may lead to a more serious failure later... or = maybe not. Getting the highest reliability can only be accomplished by = getting to the real root cause of each = failure.

If there has been a consistent pattern = of failure of the Lancair master solenoids activating the gear pump then = I am all in finding the cause and a different or added component which = has been proven in at least twenty or so installations throughly tested = across the four seasons. If there is no failure pattern then putting in = a seemingly better part is lose-breakeven = poker.

My vote is to keep the fleet as uniform = as possible so real reliability issues can be isolated. If there is no = consistent component usage, identifying real problems and achieving real = quality will be impossible. Dreaming up fancy designs is fun. Real = reliability is very hard to achieve and much less/no fun. We Americans = are an innovative lot. That is why Japan kicked our butt in the 70's and = 80's.

Sorry to be a quality zealot but I was = part of the problem back then and learned the hard way along with = everyone else.

Jack = Morgan

On Nov 30, 2013, at 6:00 AM, Lancair = Mailing List wrote:


On Nov 29, 2013, at 6:53 PM, Jack = Morgan wrote:

Hi John,

A = good rule of thumb on dc motors is 4 to 1 so your measurement seems = good. Your readings are also consistent with the 35 amp breaker which I = understand is typical for the pump.

Inductive = loads like the motor are easiest to turn on for relays since the = contacts are made before the current reaches the locked value. = Incandescent lamps are the worst case turn on load..... 10 to 1 is the = rule of thumb (no kidding) for the inrush into a cold lamp. With only = the inductance of the connecting wires the relay really sees an inrush = while it is making contact in lamp circuits.

If = a normally sized relay were to break with the pump rotor locked it would = be highly stressed, maybe even fail. Most designers rely on the breaker = to trip to protect the wiring, motor, and relay and ignore the unlikely = possibility of the relay being turned off during the short time it takes = the breaker to trip with a locked motor. The solenoid Lancair recommends = is capable of surviving turning off the starter for awhile so won't be = damaged in any case. Nothing like belt and = suspenders.

Jack Morgan

=

= --Apple-Mail=_7BAA3F4A-6C9B-4460-911F-21113931BE6B--