X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Received: from x.itlnet.net ([64.19.112.9] verified) by logan.com (CommuniGate Pro SMTP 5.1.6) with ESMTPS id 1846151 for flyrotary@lancaironline.net; Sun, 18 Feb 2007 22:27:51 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.19.112.9; envelope-from=jwvoto@itlnet.net Received: from smtpav.service (email2.itlnet.net [192.168.10.157]) by x.itlnet.net (8.13.1/8.13.1) with SMTP id l1J3QpmZ010760 for ; Sun, 18 Feb 2007 21:26:52 -0600 Received: from JWVOTO (unverified [64.19.116.222]) by mail.itlnet.net (Rockliffe SMTPRA 7.0.3) with ESMTP id for ; Sun, 18 Feb 2007 21:26:30 -0600 Message-ID: <007401c753d5$d0ad3460$de741340@JWVOTO> From: "Wendell Voto" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: CBs and fuses Date: Sun, 18 Feb 2007 21:26:28 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0071_01C753A3.7336E2E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MIMEOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 X-ITLnet-MailScanner: Found to be clean X-ITLnet-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=-2.463, required 4, autolearn=not spam, BAYES_00 -2.60, FORGED_RCVD_HELO 0.14, HTML_MESSAGE 0.00) This is a multi-part message in MIME format. ------=_NextPart_000_0071_01C753A3.7336E2E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable > SNIP > >=20 > > I am curious what PTCs you are using. I used PTCs > > on some circuits. I used=20 > > a Buss ATC form breaker, removed the bimetallic and > > soldered a PTC to the=20 > > frame. Then plugged into a ATC fuseblock. This > > worked well, bit I am=20 > > curious if you found a packaged PTC. > >=20 > > Thanks, > > Joe > >=20 Concerning the PTC devices, I was interested in them and a friend also = building a Cozy wants to use the PTC devices but I am reluctant to say = to use them. If correct, many of the ones Mouser lists that allow high = current (1 - 18 amp) seem to have an awfully high holding current; that = is, the current to maintain the device temp to hold it in the tripped = state. Be careful of the device you choose, it's holding current could = be 50% of the trip value (Littel 30R series for instance). This would = not be good for protecting the wiring. Also, you need to know the max interrupt current. A battery can dump a = lot of current through a fuse before it goes and it must be able to = interrupt that current. A typical 5 amp fuse can flow over 75 amp in a = battery supply situation before it blows. Some fuses might actually weld = together and never interrupt the current when used in a battery powered = situation. I had to do some UL testing on some fuses many years ago and = it would surprise you how much current a small fuse will pass before = blowing. Will your wire take the current that a direct short can = deliver, of course different for each situation, something to think = about even when using breakers. This is why they need to rated for = battery supply use. Wendell=20 ------=_NextPart_000_0071_01C753A3.7336E2E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

> SNIP
> >
> > I am curious what PTCs you are = using.  I used PTCs
> > on some circuits. I used
> = > a=20 Buss ATC form breaker, removed the bimetallic and
> > soldered = a PTC to=20 the
> > frame.  Then plugged into a ATC fuseblock. =20 This
> > worked well, bit I am
> > curious if you = found a=20 packaged PTC.
> >
> > Thanks,
> > = Joe
> >=20
Concerning the PTC devices, I was interested = in them and=20 a friend also building a Cozy wants to use the PTC devices but I am = reluctant to=20 say to use them.  If correct, many of the ones Mouser lists that = allow high=20 current (1 - 18 amp) seem to have an awfully high holding current; that = is, the=20 current to maintain the device temp to hold it in the tripped = state.  Be=20 careful of the device you choose, it's holding current could be 50% of = the trip=20 value (Littel 30R series for instance).  This would not be good for = protecting the wiring.
 
Also, you need to know the max interrupt = current. =20 A battery can dump a lot of current through a fuse before it goes and it = must be=20 able to interrupt that current. A typical 5 amp fuse = can flow over 75=20 amp in a battery supply situation before it blows. Some fuses might = actually=20 weld together and never interrupt the current when used in a=20 battery powered situation. I had to do some UL testing on some = fuses=20 many years ago and it would surprise you how much current = a small fuse=20 will pass before blowing. Will your wire take the current that a = direct=20 short can deliver, of course different for each situation, something to = think=20 about even when using breakers.  This is why they need to = rated=20 for battery supply use.
 
Wendell 
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