X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 21 Oct 2007 22:05:30 -0400 Message-ID: X-Original-Return-Path: Received: from vms046pub.verizon.net ([206.46.252.46] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2399239 for lml@lancaironline.net; Sun, 21 Oct 2007 20:26:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=206.46.252.46; envelope-from=tom.gourley@verizon.net Received: from jacky0da39824a ([71.111.153.83]) by vms046.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0JQA00F12EIYU5E9@vms046.mailsrvcs.net> for lml@lancaironline.net; Sun, 21 Oct 2007 19:25:51 -0500 (CDT) X-Original-Date: Sun, 21 Oct 2007 17:25:43 -0700 From: "Tom Gourley" Subject: Master solenoid heat experiment X-Original-To: "Lancair Mailing List" Reply-to: "Tom Gourley" X-Original-Message-id: <003501c81442$159dcf80$640610ac@jacky0da39824a> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-Mailer: Microsoft Outlook Express 6.00.2900.3138 Content-type: multipart/alternative; boundary="----=_NextPart_000_0032_01C81407.68876750" X-Priority: 3 X-MSMail-priority: Normal References: This is a multi-part message in MIME format. ------=_NextPart_000_0032_01C81407.68876750 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable After reading recent posts about hot master solenoids I ran a brief test = today. I placed a solenoid (Master Relay, 12 Volt, Continuous, part = number 5485 from Aerocraft Parts) out in the open on my workbench, not = mounted to anything, and hooked it up to a power supply and put a = current meter in line with it. I adjusted the power supply so that I = had 13.5V between the connection posts. This was in a closed hangar so = there was no air movement over the workbench but it was completely open. = The ambient temperature was 60 F. The initial current reading was 0.80 = Amps. At 13.5V that means the solenoid was dissipating 10.8W. After 30 = minutes the voltage was still at 13.5V but the current had dropped to = 0.58A (7.83W) because the solenoid had warmed up. How warm? According = to a thermocouple the hottest spot I could find was almost 130 F. I can = see where a longer energized period combined with higher ambient = temperature would make the solenoid to hot to touch comfortably, = possibly hot enough to burn your fingers. Note that this was a sample = size of one and I don't have any data on the variability one should = expect to see from part to part. I stopped the test after 30 minutes because my wife called and said she = was starting to cook dinner. Dinner sounded better than watching a = solenoid heat up so I went home. Tom Gourley ------=_NextPart_000_0032_01C81407.68876750 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

After reading recent posts about hot = master=20 solenoids I ran a brief test today. I placed a solenoid (Master = Relay, 12=20 Volt, Continuous, part number 5485 from Aerocraft Parts) out in the = open on=20 my workbench, not mounted to anything, and hooked it up to a = power=20 supply and put a current meter in line with it. I adjusted the = power=20 supply so that I had 13.5V between the connection posts. This was = in a=20 closed hangar so there was no air movement over the workbench but it was = completely open. The ambient temperature was 60 F. The = initial=20 current reading was 0.80 Amps. At 13.5V that means the solenoid = was=20 dissipating 10.8W. After 30 minutes the voltage was still at 13.5V = but the=20 current had dropped to 0.58A (7.83W) because the solenoid had = warmed=20 up. How warm? According to a thermocouple the hottest spot I = could=20 find was almost 130 F. I can see where a longer energized period = combined=20 with higher ambient temperature would make the solenoid to hot to touch=20 comfortably, possibly hot enough to burn your fingers. Note that = this was=20 a sample size of one and I don't have any data on the variability one = should=20 expect to see from part to part.

I stopped the test after 30 minutes = because my wife=20 called and said she was starting to cook dinner. Dinner sounded = better=20 than watching a solenoid heat up so I went home.

Tom Gourley

------=_NextPart_000_0032_01C81407.68876750--