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houlihan(at)blueyonder.co
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 Posted: Fri Jan 17, 2014 2:31 pm Post subject: Other items on the Silent-hektik web site |
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Following on from the regulator item have a look at this on their web site
http://www.silent-hektik.com/UL_912_1.htm
My German is non existent so I may have got this all wrong.
Tim
[quote][b]
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grahamsingleton(at)btinte
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| Posted: Fri Jan 17, 2014 3:11 pm Post subject: Other items on the Silent-hektik web site |
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That looks very nice! Bout time too!
Graham
From: houlihan <houlihan(at)blueyonder.co.uk>
To: europa-list(at)matronics.com
Sent: Friday, 17 January 2014, 22:30
Subject: Other items on the Silent-hektik web site
Following on from the regulator item have a look at this on their web site
http://www.silent-hektik.com/UL_912_1.htm
My German is non existent so I may have got this all wrong.
Tim
[quote]httphttp://www.matronics.com/contribution=============
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budyerly(at)msn.com
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| Posted: Sat Jan 18, 2014 3:48 pm Post subject: Other items on the Silent-hektik web site |
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<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Graham and other Regulator Haters:
The Silent-hektik (SH) may be just the ticket guys.
The GR6 I am sure is fine, but for the bucks it is not a credit card buy and plug and play as is the SH. It is LAA approved though.
I have had two Regulator failures in 12AY. The first was a result of a shorted stator. Not the Regulators fault.
The second due to a nasty bad habit which weakened the fragile innards of the poor Ducati. Others were lost due to high current load.
Recently I had a hard week of learning as Gary Leinberger and I did some mods to his electrical, adding a gear driven B&C Alternator to his airplane and splitting the buss to reduce the load on his Ducati/Rotax alternator.
We immediately found trouble with the newly installed Ducati. It would overvolt, then the OVP would kill the alternator field or Control voltage. Which is really ODD.
In Normal Troubleshooting:
Typically I look for a C wire problem with the Ducati. If the voltage output is out of tolerance at 3-4000 RPM I go down to Lockwood and use their test bench. You can do it on the aircraft also. Hook up a 15 amp load ( I use three H4 auto driving lights for about 150Watts hooked up to the alternator stud and don't power up any avionics or other bus related items) and check the voltage output on regulator. I check the R and B+ volts against the C wire (Control) and jot the info down. I put a rag or towel around the Ducati to check how hot the unit is getting (always fun around a whirling propeller). Usually it is only slightly warm. If the two voltages are the same, at about 13.5-13.8 and the lights are nice and bright. Good to go.
If you have your ammeter set up as a load meter and another as an charge meter, you can easily do the same using your power hungry panel and lights. The objective is to have a steady draw on the alternator and to check the output and control voltages which should be the same... At Lockwood I drink coffee and watch.
High voltage output is not common and as has been reported in this thread as far back as 2006, if the C voltage is low, this can drive the output voltage up, trying to get the battery voltage back to its 12.0. Our problem was not that. The C volts to B+ was within 0.1 volts. Why the high voltage? I found through Lockwood that the RV12 community was having a similar problem in their electronic busses... It is bus related.
Basic Ducati understanding has been commented on before by smarter people than I:
The Ducati is a switching regulator using Thyristors, which are nothing more than fast acting switches, along with diodes to output and control DC voltage. Remembering back to my younger days with point controlled regulators, I knew that the entire system (battery, resistance and voltage output of the dynamo all had to meet specs for the regulator to cycle its switching relay properly to control the battery voltage for charging. Since the Ducati converts AC current to DC via a set of diodes, (making a pulsed and a somewhat noisy signal), it then adjusts the voltage by simply cutting off the power pulses shutting off the current (dumping it to ground) through the Thyristors and are controlled by a clever set of transistors and resistors which feed the dump signal (or switch signal) to the Thyristors. As the voltage drops, the Thyristors again switch off, and power is restored and the cycle continues in this on and off scenario. Thyristors pulse really fast (100,000 times per minute) and don't wear out normally. However, they do get abused by either drawing too much current than designed when locked in the on position, trying to charge a poor battery, or the bus voltage is too low being supplied back to the C terminal causing the Thyristors to again stay open too long.
For proper performance, the battery voltage must be up to spec. There can be no voltage drop between the C and R+. And the current draw on the bus cannot exceed the rated output or the regulator, lest components get hot or just burn out.
The light circuit is really a neat thing. It is C voltage run through a diode that goes to L spade then to the bulb (there is more to it than that but simply put, it is slightly lower voltage than C). The other leg of the bulb goes to the C. With R/B+ and C equal, and only getting battery voltage, the Light goes on because of the voltage difference between C and L. Essentially, as the alternator supplies power, the voltage of the L leg and C leg become equal and the bulb extinguishes as it has equal power to each leg. Of course it is important to note that if the transistor regulator circuit goes bad, you don't get voltage regulation or C control (unit shuts down) and the light is inoperative. So the only real means of knowing if your alternator has failed is an ammeter and a voltmeter in this failure mode. This is common in all regulators.
Back to our problem:
I contacted a long time producer of electronic busses, Control Vision (Anywheremap) and talked to their lead engineer. It seems that our Ducatis do not play well with a PTC controlled circuit. I don't know that much about PTCs but essentially they are a PNPN type silicone transistor of sorts that as voltage is applied, internal resistance in the PTC builds (causing heat) and if too high of a current is applied, it hits its switching temp and the resistance in the PTC goes up exponentially. Effectively shutting off power due to high resistance. Once power is removed from the PTC, it resets itself. Kind of like a Thyristor, and like a switch. These items are affected by bus voltage, panel temperature, power pulses and because they have internal resistance can lower the C voltage causing the regulator to overvolt.
Since most of these automatic busses have over voltage protection (OVP) if the regulator puts out too much voltage due to the control voltage drop, then the buss shuts down the C voltage to the regulator to stop the overvoltage condition. The Alt warning light comes on (no volts at the C terminal) and the regulator is shut off.
The only way to reset the Alternator Control PTC is shut off the Master Switch, killing power to the bus. NOT my favorite thing to do at night or with an EFIS, as all goes tumbling into the night until we get power back. (That’s why its smart to have a battery back up.)
Our solution was to wire the Alternator and Battery leads from the firewall studs to the EXP bus. Eliminating the OVP protection but safe as the Ducati/Rotax just can't produce over 15 volts. Then run a wire from the R+/B from the stud to the alternator switch and then to the C. This allows for independent control of the regulator should it have to be shut down in flight. Once the Volts from the fresh battery and the resistance of the PTC alternator supply spade and OVP was removed from the control circuit, all is well so far even with a 12.5 volt Odyssey battery in the system.
One other problem, which is my nasty habit, is after engine start, I immediately engage the avionics bus switch (EFIS and Garmin 430s take a while to boot). I was chastised by an automotive friend of mine. After engine start, the battery is of course down for a few seconds. At idle, the the Rotax alternator is supplying very little power, and the regulator circuits go wide open delivering power to the battery for charging. Normally a good battery in summertime takes 10-15 seconds to recover at 13.6 volts, but our little birds can barley meet 12 sometimes unless we spin up the RPM to 2500. In winter, more time is necessary for the battery to recover. So the regulator stays in wide open mode trying to supply voltage it can't, and it preheats the regulator circuit. He commented that a little patience (something I do not have) by checking of the engine instruments after start and then the status of charging on the Ammeter and volt meter would show me the battery state before I slammed the bus on. So I am now going to spool up the engine to 2500 and let it run there until the amps fall off and the volts stabilize, then turn on the avionics goodies. I tried the operation on Gary's plane and sure enough, the battery took a good 10 seconds to recover from start. Then I spun up the engine, smacked on the avionics (10 amps or so) and the regulator took it all in stride. 12 AY also responded quite well to the same procedure and cured my EFIS hang-up during start.
In a nutshell, Ducatis are a bit fragile. Keep the battery well charged (and properly charged by the battery manufacture's recommendation), have a little patience and let the battery recover before turning on all the power hogs. Pay attention to the R/B+ to C voltage on panel install to avoid problems.
If the Ducati is expected to produce 15 amps below 5000 RPM, you may in fact find that they only last a year or so. SH seems to know all this, but the translation is a bitch.
I hope to test one of these units and see how they hold up soon.
Odyssey battery owners should check out the www.odysseybattery.com site for proper storage, charging (and chargers) and recovery of these batteries. Trickle chargers are not the best for these batteries.
Regards,
Bud Yerly
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