AeroElectric-List Digest Archive

Sat 07/14/12


Total Messages Posted: 7



Today's Message Index:
----------------------
 
     1. 04:29 AM - Re: Over-voltage Circuit Trips (Fred Stucklen)
     2. 07:54 AM - Re: solid wire in PGID terminals (Robert L. Nuckolls, III)
     3. 07:56 AM - Re: Over-voltage Circuit Trips (Robert L. Nuckolls, III)
     4. 09:22 AM - =?utf-8?B?QWx0ZXJuYXRvciBraWNraW5nIG9mZiBsaW5lLg==? (=?utf-8?B?YW1leWVyQG1pbC1hbWF4LmNvbQ==?=)
     5. 10:17 AM - Re: Alternator kicking off line. (Robert L. Nuckolls, III)
     6. 10:28 AM - grounding (bob noffs)
     7. 02:35 PM - Hints for recycling furnace blowers . . . (Robert L. Nuckolls, III)
 
 
 


Message 1


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    Time: 04:29:20 AM PST US
    From: "Fred Stucklen" <wstucklen1@cox.net>
    Subject: Re: Over-voltage Circuit Trips
    Jack, Check for a loose connection in the field circuit, especially in the alternator connector (if you have one). Any Interruption in the field circuit current (after the regulator) will cause an overvoltage condition when the connection is reestablished. This is especially true for a slow responding regulator... Engine heat will sometimes cause the alternator connector contacts to become loose. Also check for an intermittent regulator ground .. If the regulator is internal to the alternator, check for an intermittent engine ground back to the battery. Fred Stucklen RV-7A N924RV 750 Hrs (Flying RV-6A N926RV 875 Hrs (Sold) RV-6A N925RV 2008 Hrs (Sold) Time: 12:16:39 PM PST US From: Jack Haviland <jgh2@charter.net> Subject: Re: Over-voltage Circuit Trips On Jul 12, 2012, at 5:40 PM, Robert L. Nuckolls, III wrote: >> Since my RV first flew about a year ago the over-voltage circuit has frequently tripped shortly after take off. Resetting the 5 amp pull-able circuit breaker once or twice generally prevents a re-occurence for the remainder of the flight but I need to determine the root cause and correct it. > > Jack, I'm not ignoring you. Will have a response > and some suggestions in the morning . . . Thanks Bob. A short flight this morning demonstrated that replacing the suspect circuit breaker did not correct the situation. The main bus was at 12.6 volts prior to start and read a solid 14.2 volts during the flight. The EIS (on the endurance bus) was displaying around 13.6 volts but the breaker tripped twice during each of two climbs to the pattern. All connections and terminals in the field circuit appear to be secure. The aircraft instrumentation does not include a recording capability. Suggestions will be greatly appreciated! Jack


    Message 2


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    Time: 07:54:18 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: solid wire in PGID terminals
    At 07:58 PM 7/13/2012, you wrote: > >Turns out I'm misinformed again. The pgid terminal specs in the >Digikey specify SOLID OR STRANDED wire. > >The only possible defense of my error I can find is that some larger >crimp on lugs (starting at #8 wire) specify that they are for >stranded wire, although they don't specifically prohibit solid wire. > >Thanks again for helping me get things right. Looking though the AMP literature, they DO make a distinction between terminal types for solid vs. stranded wire. http://www.te.com/catalog/GeneralInfo/sbli04a.gif We can see that AMP offers a 'specialized' product tailored to single-strand wire. Adding a degree of 'roughness' to the inside surface of the wire grip increases tensile strength of the joint (of negligible concern in aircraft wiring) and an increase in electrical contact area. This last benefit is also a tiny percentage increase. Since we don't even begin to load wires in airplanes like they do in ground based vehicles, this too would be a no-big-deal benefit. This is not intended to detract from the engineering that goes into AMP products . . . at the same time, I deduce that it's not significant to the task of wiring a diode to the outside of a contactor. Bob . . .


    Message 3


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    Time: 07:56:48 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Over-voltage Circuit Trips
    P.S. forgot to mention that each revolution of the calibration pot on my modules moves the setpoint about 0.5 volts. So if you're getting nuisance trips with a bus voltage that is running in normal ranges, you can try one half turn of counter-clockwise adjustment and see if the trips stop. Bob . . .


    Message 4


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    Time: 09:22:11 AM PST US
    From: "=?utf-8?B?YW1leWVyQG1pbC1hbWF4LmNvbQ==?=" <ameyer@mil-amax.com>
    Subject: =?utf-8?B?QWx0ZXJuYXRvciBraWNraW5nIG9mZiBsaW5lLg==?
    SSBhbSBoYXZpbmcgYW4gaXNzdWUgd2hlcmUgd2hlbiBJIGtleSB0aGUgTWljIG9uIG15IEdhcm1p bjQzMCBjb21tICggbXkgb25seSBjb21tIHJhZGlvKSwgbXkgYWx0ZXJuYXRvciBraWNrcyBvZmYg bGluZS4gVGhpcyBkb2Vzbid0IGhhcHBlbiBvbiB0aGUgZ3JvdW5kIHNob3J0bHkgYWZ0ZXIgc3Rh cnRpbmcsIGJ1eSB3aGVuIGFpcmJvcm5lLCBldGMuLi4gSXQgbm93IG9jY3VycyBhbG1vc3QgMTAw JSBvZiB0aGUgdGltZS4gVGhpcyBoYXBwZW5lZCBmb3IgYSB3aGlsZSBpbnRlcm1pdHRlbnRseSwg YnV0IGlzIG5vdyB2ZXJ5IGZyZXF1ZW50LiBJIGhhdmUgYSBDZXNzbmEgc3R5bGUgc3BsaXQgc3dp dGNoIGFuZCBuZWVkIHRvIHR1cm4gb2ZmIGFuZCBiYWNrIG9uIHRoZSBhbHRlcm5hdG9yIHNpZGUg dG8gcmVzdG9yZSBjaGFyZ2luZyB0byB0aGUgc3lzdGVtLiBUaG91Z2h0cz8gVHJvdWJsZXNob290 aW5nIHN0ZXBzPyBJRDEwVCBlcnJvcnM/IAoKSGFwcHkgRmx5aW4nIQpBbmR5CgoKCg=


    Message 5


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    Time: 10:17:22 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Alternator kicking off line.
    At 11:20 AM 7/14/2012, you wrote: >I am having an issue where when I key the Mic on my Garmin430 comm ( >my only comm radio), my alternator kicks off line. This doesn't >happen on the ground shortly after starting, buy when airborne, >etc... It now occurs almost 100% of the time. This happened for a >while intermittently, but is now very frequent. I have a Cessna >style split switch and need to turn off and back on the alternator >side to restore charging to the system. Thoughts? Troubleshooting >steps? ID10T errors? > >Happy Flyin'! >Andy This has the smell of an RF interference issue between ov sense circuits and your comm transmitter. What kind of airplane? What kind of regulator/ov protection system? Where is your antenna located? Have you checked the SWR on the antenna to be sure of feed line integrity? Bob . . .


    Message 6


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    Time: 10:28:13 AM PST US
    Subject: grounding
    From: bob noffs <icubob@gmail.com>
    hi all, thanks to all who responded for all the info, ideas. sooooooooo here is my plan i will use a new 55 gal drum with a 12 volt pump and conductive hose to a metal end. pump will be grounded to metal rod in ground. i picked up from all the info that electrical connection to hose end and airplane tank before fueling is the key to prevent sparks so i will either connect pump to exhaust pipes or tank rim to hose end before filling. i will pick up a new oil drum for $20 next weekand start to put this together. thanks again, bob noffs


    Message 7


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    Time: 02:35:44 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Hints for recycling furnace blowers . . .
    For years, I've used salvaged the guts of furnaces to fabricate utility blowers for carpet drying, workspace comfort, paint drying, etc. Dr. Dee occasionally uses an energetic blower outdoors when gardening in hot, low-wind weather. These blowers are compact (motor mounts inside the blower wheel) and often include some variable speed options. They can be had for very little from HVAC companies that change out old furnace and a/c units. I just picked one up at a garage sale for $20 where the owner had already mounted it to a base and fitted with a carrying handle and line cord. Most DIY conversions I've seen in the wild do not account for the fact that these blowers are designed to push LOTS of air through a maze of ducts. I.e., they are intended to do more WORK than just move xx cubic feet of air per minute. There is back-pressure of the duct work to consider. Referring to an exemplar speed vs. torque and current curve . . . [] We can see that there's a 'hump' in motor's torque curve. We also see that rated operating characteristics for the motor are on the right-side of that hump. This means that for the motor to start up and accelerate past the hump, the load on the motor MUST be less than the 'break down' torque else the thing won't make it up the hump to it's operating point. I knew that the blower I just bought was exceedingly crippled in performance . . . it's outlet port was wide open. Sure 'nuf. Got it home, plugged it in . . . it did indeed move some air. The snap-on ammeter read 4.5 amps. But operated completely open loop, it gulped in and tried to accelerate too much air. I took a scrap of plywood and blocked off about 1/3 of the outlet. The motor accelerated up over the hump, rpm rose dramatically and it really began to move some air! I've added a permanent baffle adjusted so that the motor draws about 3.5 amps. That's 'cause I'm too lazy to take it apart and see if the motor frame is marked with rated load current. If I knew what the rated current was, I'd adjust the baffle to achieve that current. In any case, it now draws 1 amp less than when I bought it and moves a great deal more air. This is something to remember about induction motor characteristics . . . they must be loaded well down the right side of the 'hump'. If any of you have ever used an induction motor lawn mower, you may have experienced what one might call 'motor stall' when pushing too rapidly into tall weeds . . . the speed is loaded down to where the motor tumbles down the front side of the hump. You have to pull back and let it recover. For you techno-nerds, max torque (or breakdown torque) from an induction motor occurs at a 'slip frequency' in the squirrel cage where inductive reactance is equal to the DC resistance of the cage conductors. It's 105 out there today . . . added air motion in the shop will be welcome. Bob . . .




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