X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-db02.mx.aol.com ([205.188.91.96] verified) by logan.com (CommuniGate Pro SMTP 6.0.4) with ESMTP id 6172192 for lml@lancaironline.net; Sat, 30 Mar 2013 10:23:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.91.96; envelope-from=Sky2high@aol.com Received: from mtaomg-db01.r1000.mx.aol.com (mtaomg-db01.r1000.mx.aol.com [172.29.51.199]) by imr-db02.mx.aol.com (Outbound Mail Relay) with ESMTP id 6AC851C0000E8 for ; Sat, 30 Mar 2013 10:22:28 -0400 (EDT) Received: from core-mta001c.r1000.mail.aol.com (core-mta001.r1000.mail.aol.com [172.29.234.129]) by mtaomg-db01.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id 283F1E000087 for ; Sat, 30 Mar 2013 10:22:28 -0400 (EDT) From: Sky2high@aol.com Full-name: Sky2high Message-ID: <1a1e6.6c9d4e8b.3e884f23@aol.com> Date: Sat, 30 Mar 2013 10:22:28 -0400 (EDT) Subject: Re: [LML] Re: Hydraulic gear pump failure - Relays To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_1a1e6.6c9d4e8b.3e884f23_boundary" X-Mailer: AOL 9.6 sub 168 X-Originating-IP: [67.175.156.123] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1364653348; bh=LjJFj57vP/ofeXgxkdfdW7Y6N6smsLea8smdQ74qFJA=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=FvVeX3xWJQB2Z9dJcJqtBYKqA3OloFvKB+fYQeIuCYNHNoUSqU5ASbwYSpFTmbWOl RPGfnNk7MpRXGRUia20OF084WCqd2rY2LSbuiACYJwDvM/V8kXaUwErhth/L9N34NB nDBVd13UOVkodRyuAwZLmt3k3/9aY9jO196B3pcg= X-AOL-SCOLL-SCORE: 0:2:417130304:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d33c75156f524539c --part1_1a1e6.6c9d4e8b.3e884f23_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en So many ways to skin the cat if you can catch it........ =20 =20 In a message dated 3/30/2013 9:15:38 A.M. Central Daylight Time, =20 super_chipmunk@roadrunner.com writes: =20 Thanks Scott- That=E2=80=99s a good point that I had forgotten abo= ut.=20 Another method is to use Metal Oxide Varistors- something Bob Nuckolls=20 (AeroElectric Connection) used to recommend. They absorb spikes and are=20 bidirectional so there=E2=80=99s no worry about polarity. =20 I used Panasonic ERZV20D180=E2=80=99s on the 14V Navion relays when I got= a 337=20 for a dual battery system. That was okayed by an aircraft designer/ DAR so= =20 I have some confidence in the choice. There has been no problem with the = =20 system during six years of use. =20 I just ordered ERZV20D390=E2=80=99s for the 28V Lancair relays- they=E2=80= =99re =20 comparable in performance to the others but higher operating voltage. Pana= sonic is=20 apparently discontinuing the series so if anyone is interested they might= =20 want to buy soon. Others are available but I didn=E2=80=99t find such high = capacity=20 in a quick search. Mouser Electronics has them at reasonable prices. =E2= =80=93Bill=20 Wade =20 =20 =20 From: _Sky2high@aol.com_ (mailto:Sky2high@aol.com) =20 Sent: Thursday, March 28, 2013 2:12 PM To: _lml@lancaironline.net_ (mailto:lml@lancaironline.net) =20 Subject: [LML] Re: Hydraulic gear pump failure - Relays =20 =20 Bill, et al, =20 Relays should have a diode reverse connected across the coil to stop the = =20 voltage surge generated by the field collapse when power is removed from th= e =20 coil. This will help protect the pressure switch contacts. =20 Grayhawk=20 =20 =20 In a message dated 3/28/2013 12:58:55 P.M. Central Daylight Time, =20 super_chipmunk@roadrunner.com writes: =20 Would there be any drawback to using a higher- rated contactor? I found=20 the Lancair part to be a P.O.S.- it was marked continuous duty but when pu= t=20 on a power supply it rapidly overheated and shorted to the case. =20 Instead I=E2=80=99m using an antique 50A Leach B-5B aircraft style that eas= ily =20 operated for hours. The pump supplied with my IV-P draws a maximum of 50A, = so=20 the Leach might be marginal but I think I=E2=80=99ll try it initially. =20 On Colin=E2=80=99s recommendation I also purchased a TYCO LEV100A5ANH , rat= ed 100A=20 that I could use instead, or elsewhere. The Leach draws 0.16A, the TYCO =20 draws 0.25A at 28V. The Lancair- supplied Suco pressure switch is rated for= =20 4A as best I can determine so either unit should be compatible. =20 I don=E2=80=99t know what other models might use but consider the contac= ts=20 inside the pressure switches. If they should get overloaded and weld close= d the=20 effect would be the same as welding the relay points. -Bill Wade =20 =20 =20 From: _Gary Casey_ (mailto:casey.gary@yahoo.com) =20 Sent: Thursday, March 28, 2013 9:36 AM To: _lml@lancaironline.net_ (mailto:lml@lancaironline.net) =20 Subject: [Norton AntiSpam][LML] Re: Hydraulic gear pump failure - Relays =20 =20 =20 Pardon me if I'm jumping into a discussion a little late (and a dollar =20 short), but there might be some confusion on how and why relays are designe= d =20 for intermittent duty. As an example, take a standard master relay. It i= s=20 rated for continuous duty and something like 80 amps. That means the coil= =20 won't overheat if left on forever and that the contacts also won't overhea= t=20 when passing 80 amps and that the contacts won't weld when interrupting 80= =20 amps. It is often the limitations when opening the circuit that=20 determines the rating. Current will try to keep flowing and if the contac= ts don't=20 separate rapidly and with enough force the inevitable arc could create=20 enough heat to weld the contacts and prevent opening. If it is desired to= =20 design a relay in the same package (for cost, size and weight reasons) tha= t can=20 be used intermittently to pass a much higher current the design parameters= =20 are different. More force is required to increase the rate at which the= =20 contacts are opened so a higher force spring is installed. Then more forc= e=20 is required to close the contacts, so fewer turns of heavier wire are used= =20 in the coil (that's right, FEWER turns, but that's another discussion). T= he=20 result is that the relay can now successfully switch maybe 300 amps, but= =20 the coil will overheat after a few minutes of operation. That's the=20 difference between a master and a starter relay. And I have never, ever h= eard of =20 using a relay as the "weak link" in the system. Gary ps: My Lancair list emails now come all messed up (see below). Why is=20 that? Am I doing something wrong? =20 The only caveat with that fix, Fred, is that intermittent relays are ther= =3D e for a purpose. They are supposed to be the weak link in a circuit where = =3D a continuous stuck relay could result in greater problems than a failure.=3D= 20 Does that protective function matter in this circuit?=3D0D Should be considered.=3D0D John=3D0D --part1_1a1e6.6c9d4e8b.3e884f23_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
So many ways to skin the cat if you can catch it........
 
In a message dated 3/30/2013 9:15:38 A.M. Central Daylight Time,=20 super_chipmunk@roadrunner.com writes:
=
Thanks Scott-
           &n= bsp;         =20 That=E2=80=99s a good point that I had forgotten about. Another method is= to use Metal=20 Oxide Varistors- something Bob Nuckolls (AeroElectric Connection) used to= =20 recommend. They absorb spikes and are bidirectional so there=E2=80=99s no= worry about=20 polarity.
 
  I used Panasonic ERZV20D180=E2=80=99s on the 14V Navion relay= s when I got=20 a 337 for a dual battery system. That was okayed by an aircraft designer/= DAR=20 so I have some confidence in the choice. There has been no problem with t= he=20 system during six years of use.
 
I just ordered ERZV20D390=E2=80=99s for the 28V Lancair relays- they= =E2=80=99re=20 comparable in performance to the others but higher operating voltage.=20 Panasonic is apparently discontinuing the series so if anyone is interest= ed=20 they might want to buy soon. Others are available but I didn=E2=80=99t fi= nd such high=20 capacity in a quick search. Mouser Electronics has them at reasonable pri= ces.=20 =E2=80=93Bill Wade
 
Sent: Thursday, March 28, 2013 2:12 PM
Subject: [LML] Re: Hydraulic gear pump failure -=20 Relays
 
=
Bill, et al,
 
Relays should have a diode reverse connected across the coil to stop= the=20 voltage surge generated by the field collapse when power is removed from = the=20 coil.  This will help protect the pressure switch contacts.
 
Grayhawk
 
In a message dated 3/28/2013 12:58:55 P.M. Central Daylight Time,=20 super_chipmunk@roadrunner.com writes:
  Would there be any drawback to using a higher- rated contac= tor?=20 I found the Lancair part to be a P.O.S.- it was marked continuous duty = but=20 when put on a power supply it rapidly overheated and shorted to the=20 case.
 
Instead I=E2=80=99m using an antique 50A Leach B-5B aircraft style= that easily=20 operated for hours. The pump supplied with my IV-P draws a maximum of 5= 0A,=20 so the Leach might be marginal but I think I=E2=80=99ll try it initiall= y.
 
On Colin=E2=80=99s recommendation I also purchased a TYCO LEV100A5= ANH , rated=20 100A that I could use instead, or elsewhere. The Leach draws 0.16A, the= TYCO=20 draws 0.25A at 28V. The Lancair- supplied Suco pressure switch is rated= for=20 4A as best I can determine so either unit should be compatible.
 
  I don=E2=80=99t know what other models might use but consid= er the=20 contacts inside the pressure switches. If they should get overloaded an= d=20 weld closed the effect would be the same as welding the relay points.&n= bsp;=20 -Bill Wade
 
From: Gary=20 Casey
Sent: Thursday, March 28, 2013 9:36 AM
Subject: [Norton AntiSpam][LML] Re: Hydraulic gear pump fai= lure=20 - Relays
 
Pardon me if I'm jumping into a discussion a little late (and a do= llar=20 short), but there might be some confusion on how and why relays are des= igned=20 for intermittent duty.  As an example, take a standard master=20 relay.  It is rated for continuous duty and something like 80=20 amps.  That means the coil won't overheat if left on forever and t= hat=20 the contacts also won't overheat when passing 80 amps and that the cont= acts=20 won't weld when interrupting 80 amps.  It is often the limitations= when=20 opening the circuit that determines the rating.  Current will try = to=20 keep flowing and if the contacts don't separate rapidly and with enough= =20 force the inevitable arc could create enough heat to weld the contacts = and=20 prevent opening.  If it is desired to design a relay in the same= =20 package (for cost, size and weight reasons) that can be used intermitte= ntly=20 to pass a much higher current the design parameters are different. = ;=20 More force is required to increase the rate at which the contacts are o= pened=20 so a higher force spring is installed.  Then more force is require= d to=20 close the contacts, so fewer turns of heavier wire are used in the coil= =20 (that's right, FEWER turns, but that's another discussion).  The r= esult=20 is that the relay can now successfully switch maybe 300 amps, but the c= oil=20 will overheat after a few minutes of operation.  That's the differ= ence=20 between a master and a starter relay.  And I have never, ever hear= d of=20 using a relay as the "weak link" in the system.
Gary
ps:  My Lancair list emails now come all messed up (see=20 below).  Why is that?  Am I doing something wrong?
 
The=20 only caveat with that fix, Fred, is that intermittent relays are=20 ther=3Defor=20 a purpose.  They are supposed to be the weak link in a circuit whe= re=20 =3Dacontinuous=20 stuck relay could result in greater problems than a failure.=3D20Does=20 that protective function matter in this circuit?=3D0DShould=20 be  considered.=3D0DJohn=3D0D
<= /HTML> --part1_1a1e6.6c9d4e8b.3e884f23_boundary--