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Author Topic: ST5 with AVR connection question  (Read 32850 times)

vtmetro

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ST5 with AVR connection question
« on: January 06, 2011, 10:09:43 PM »
I've got a Kill-A-Watt and have been monitoring and adjusting the Metro for 61 Hz unloaded. But I wasn't able to control the voltage with the potentiometer on the front of (what I believe is) an AVR.

My instructions say nothing about any AVR shipped with the ST-5, but there it is anyway.

I'm attaching photos of the terminals outside the doghouse and inside. I believe that AVR came connected properly for 240 V but incorrectly for 120V , but I wanted to check that out with you all.

If you look at the external terminal photo here you see a connection diagram showing where to place two jumper lugs for either 120 or 240. In the photo the lugs are on the 2 center terminals for 240 operation.



If you measured across the two outermost terminals (U1 to U2) you'd get 240V If you measured across either the right (U1 and U6) or left pair of terminals (U2 and U5) you'd get 120V.

For 120v operation the jumpers are placed on the two outer pairs of terminals, per the diagram and then you get 120 across the pairs. Basically you're paralleling output.

Now lets look inside the box.:



The AVR is the blue box on the left. On the right are the terminals. The AVR has two thin wires coming out of it that go to the bottom two terminals. One is black and one is red.

Here's a close-up:



The two thin wires are on the right, connected between U1 and U6.

As a guess, these are sensing wires that monitor the voltage, and when the generator is configured for 240V operation, these are on one leg, and will see 120V.

However, if the jumper lugs are re-configured to give 120V, U1 and U6 are tied together, and the AVR will see zero volts (I believe). And the AVR won't work. Right?

That's what I think happened in my case when I configured the genhead for 120V. Adjusting the AVR had no effect on output voltage. When I re-configured for 240 volts, the AVR adjuster worked.

So my question is, If I want to configure for 120 V, should I also reconnect the AVR leads across the 120 V output - U5 to U6?

Thanks!

ps. (U5 to U6 would seem a better choice than U1 to U2 in case it was reconfigured as 240 V without remembering to re-connect the AVR as itwas before. The AVR would see 0 volts instead of 240, which might blow it.).
« Last Edit: January 06, 2011, 10:14:07 PM by vtmetro »

bschwartz

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Re: ST5 with AVR connection question
« Reply #1 on: January 07, 2011, 03:04:11 AM »
Yes.  If you use the 120v output only (which I recommend if you don't need 240) that is how you would hook it up.
-Brett

1982 300SD, 1995 Suburban 6.5, 1994 F250, R170, Metro 6/ sold :( , Witte CD-12 ..... What else can I run on WVO?

vtmetro

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Re: ST5 with AVR connection question
« Reply #2 on: January 08, 2011, 03:10:51 PM »
Thanks Brett,

Well, I think a split 240V setup would be more useful than a paralleled 120V.

For one thing the transfer switch I have in the house is set up for two legs. I could probably change that, but I'd like to keep it as is.

If at some point I wanted to get rid of my 120V AVR, what value wattage and resistance rheostat would be used to adjust an ST-5 as a replacement for the AVR?

Thanks!

Tijean

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Re: ST5 with AVR connection question
« Reply #3 on: January 08, 2011, 03:48:22 PM »
Vmetro, you may not need any resistance to supply the field from the harmonic winding via the bridge rectifier. The voltage  is around 60 volts and less than 3 amps. If you want to fine tune it I believe you need variable to 10 ohm and about 200 or a bit more watt rheostat.
Frank

10/1 Jkson, ST5 gen. head

bschwartz

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Re: ST5 with AVR connection question
« Reply #4 on: January 08, 2011, 03:49:45 PM »
It's a BIG one!!! Someone did the calcs a long time ago (couldn't tell you who) and it worked out to 10 Ohms at around 100 Watts.
Something like this:
http://cgi.ebay.com/OHMITE-RHEOSTAT-RLS10R-150W-10OHM-/270655405969?pt=LH_DefaultDomain_0&hash=item3f0451bf91#ht_1639wt_836

I think Marcus (mbryner) is using one.

Yes, 240 is more useful.
-Brett

1982 300SD, 1995 Suburban 6.5, 1994 F250, R170, Metro 6/ sold :( , Witte CD-12 ..... What else can I run on WVO?

buickanddeere

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Re: ST5 with AVR connection question
« Reply #5 on: January 08, 2011, 06:54:44 PM »
 I'm thinking 1 & 2 together and  5 & 6 together to parallel the windings for 120V.  A jumper across 1 to 6 and  5 to 2 look like dead shorts? Or did I miss something?

Tijean

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Re: ST5 with AVR connection question
« Reply #6 on: January 08, 2011, 09:12:42 PM »
I'm thinking 1 & 2 together and  5 & 6 together to parallel the windings for 120V.  A jumper across 1 to 6 and  5 to 2 look like dead shorts? Or did I miss something?

I see that 1 and 5 is one winding and 2 and 6 the other as shown in Bswartz diagram. Now it makes sense.
« Last Edit: January 09, 2011, 02:14:29 AM by Tijean »
Frank

10/1 Jkson, ST5 gen. head

bschwartz

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Re: ST5 with AVR connection question
« Reply #7 on: January 08, 2011, 11:08:20 PM »
-Brett

1982 300SD, 1995 Suburban 6.5, 1994 F250, R170, Metro 6/ sold :( , Witte CD-12 ..... What else can I run on WVO?

vtmetro

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Re: ST5 with AVR connection question
« Reply #8 on: January 09, 2011, 12:16:54 AM »
Vmetro, you may not need any resistance to supply the field from the harmonic winding via the bridge rectifier. The voltage  is around 60 volts and less than 3 amps. If you want to fine tune it I believe you need variable to 10 ohm and about 200 or a bit more watt rheostat.

Thanks Tijean, I do need to fine tune it as the pulley ratio I received yields 128 volts @ 60 hz. I'd like to run unloaded at 61 hz.

I also need to work on the governor spring setup, as many others have found, because my governor lets the RPM sag with load. It doesn't seem to be a reaction speed problem -- it stays consistently low, and bumping it up by hand under load causes it to return to where it was rather than improving it.

Tijean

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Re: ST5 with AVR connection question
« Reply #9 on: January 09, 2011, 12:56:05 AM »
Other words; you need a slightly greater fuel rack movement per rpm governor change. I imagine you have already found lots of posts with ideas of accomplishing it. 128 doesnt seem severe but I bet it goes higher than that for a few seconds when a heavy load is dropped. Have you checked to see what the voltage is when the gen. is totally warmed up. Dont know exactly but mine does drop off a fair bit though I dont warm it up much usually.  It probably wont take a lot of resistance to drop it enough.
Frank

10/1 Jkson, ST5 gen. head

vtmetro

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Re: ST5 with AVR connection question
« Reply #10 on: January 09, 2011, 01:05:42 AM »
It's a BIG one!!! Someone did the calcs a long time ago (couldn't tell you who) and it worked out to 10 Ohms at around 100 Watts.
Something like this:
http://cgi.ebay.com/OHMITE-RHEOSTAT-RLS10R-150W-10OHM-/270655405969?pt=LH_DefaultDomain_0&hash=item3f0451bf91#ht_1639wt_836

I think Marcus (mbryner) is using one.

Yes, 240 is more useful.


Thanks Brett. Wow, that's expensive. Since we have similar generators, have you ever measured the working resistance you ended up with?

I might make my own air wound resistor with an insulated alligator clip as a tap and work out what resistance I need that way. I don't imagine it gets adjusted much after you hit the right number for your setup.

vtmetro

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Re: ST5 with AVR connection question
« Reply #11 on: January 09, 2011, 01:11:57 AM »
Imagine the legs as below.  I think the jumpers will make sense.

http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4620&g2_serialNumber=2

Yes I think that's accurate, Brett..

Buickandeere and Tijean,  before I opened this thread I already had tried both the ST suggested setups (120 and 240) and they seemed to work. As mentioned, the 240v version worked with the adustable AVR, while the 120 V was unregulated.

I also tried an unbalanced load with the 240 setup: a 1300 watt heater on the regulated 120 volt leg. Nothing connected to the other leg. There was a sudden noticeable hum from the ST-5 and I disconnected the load as soon as I heard it, a few seconds. I'm guessing that was the AVR's doing.

Seems to me that the supplied 120V AVR really shouldn't be used in a 240 volt two leg setup, therefore, even though the generator head comes hooked up that way out of the box.

For a 240 two leg setup, voltage adjustment with a rheostat, and tuning the governor/spring setup and engine revs for frequency seems better to me.

By the way Tijean, I have read a few mentions of spring adjustment, but if you have a good reference for this for a method that you favor, on the forum, could you give me the url?

I have seen the utterpower adjuster alteration, but that seems to be aimed at linearity of response. Others seem to be removing linkage backlash with a spring. But that would remedy a slow response problem.

My problem is that the governor seems consistent (repeatable) in positioning under load, but that position is too low. George at Utterpower says 2-3 hz line variation is achievable. Mine is more than double that.

Thanks.
« Last Edit: January 09, 2011, 04:21:47 AM by vtmetro »

Tijean

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Re: ST5 with AVR connection question
« Reply #12 on: January 09, 2011, 04:04:48 PM »
Vmetro, re. governor balancing; here is a link to a thread with some ideas.

http://listerengine.com/smf/index.php?topic=5264.0

I will see if I can find one of the more general works on balancing a centrifugal governor. For starters all slack and unnecessary frictiion should be eliminated. It is likely impossible to get the system to be bang on under different loads but I think you should be able to get it down to about three cps before you start to get into occillating or hunting.
Frank

10/1 Jkson, ST5 gen. head

vtmetro

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Re: ST5 with AVR connection question
« Reply #13 on: January 09, 2011, 04:43:40 PM »
Thanks Tijean.

This morning, I reverted the terminal hookup to the paralleled 120 Volt version, and this time reconnected the 120V AVR across U5 and U6, as I mentioned in an earlier post. I was a little nervous doing this because the two thin wires from the AVR are red and black. To me, this usually means polarized DC. But of course these do go to AC terminals. I didn't know if there would be any difference in a specific color going to U5 or U6. Maybe some kind of phasing problem I wouldn't have known about?

Well, no problems. I moved red to U6, and I left the black wire where it was on U5, and fired up the 6-1. With a little adjustment I had 120.2 V at 63.5 Hz, no load. With a 1500 watt load I got 120.1V at 60.2 Hz. With a 3000 watt load I got 120.1 Hz at 58.5 Hz -- the Kill-A-Watt was flashing that lower Hz value, so perhaps that's under tolerance.

So the voltage is very well regulated, and with a parallel output, no worry about leg balancing. I'd like to get the frequency regulated a little better if possible, and will work on that.

The other problem now would be figuring out how to go to the house transfer switch which is set up for two legs.

I'd still like to also experiment with a resistance adjusted, non-AVR, 240 volt setup. It would be nice to be able to switch back and forth from 120 to 240 as needed. The generator is out in the shop, so 240V would be nice there some times. Generally the shop would need 120, and the house would only need 120V when there was a power outtage.
« Last Edit: January 09, 2011, 05:26:08 PM by vtmetro »

Tijean

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Re: ST5 with AVR connection question
« Reply #14 on: January 09, 2011, 06:01:27 PM »
Looks like the AVR is doing its job on the voltage. The frequency part is up to Mr. Lister. The slack and binding in the yoke that hooks the bellcrank to the fuel rack is a problem area. I have thought about fabricating a different arrangement there. Basically what you want to do now is to multiply slightly the movement of the fuel rack in response to a given change of motion by the governor weight/ balance spring teeter totter. The easiest thing to vary is the spring. Its tension is very close to correct but its stack rate is just a bit too steep. If you could find the same diameter and wind in a slightly longer spring then shorten the adjuster rod to reattain the same tension that would change the curve shape of its response. Just a hint that comes from experience; dont go to stretching or grinding the outside of your existing spring. Dont mess with your benchmark! Especially since what you have in voltage and frequency excursions is probably better than 95% of similar setups. The waveform and the single cylinder power pulse distortions of that setup will never satisfy really critical loads anyways.

I have the same dilemma about 120 240. The shop needs 240 but emergency for the house I would only service 120 loads. I think what we should do is get ourselves each another generator!  ;D
Frank

10/1 Jkson, ST5 gen. head