Author Topic: Voltage Rensing Relay Config - could use some help  (Read 4799 times)

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kitestrings

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Voltage Rensing Relay Config - could use some help
« on: December 30, 2013, 11:58:08 AM »
Hi.  Happy Holidays,

I've just finished up wiring our controllers, rectifier and breakers.  This is for a 15' axial.  We have two Classic 250's.  In our set up we're incorporating an Omron voltage sensing relay based on one of Rob Becker's protection schemes.  This is for high voltage protection of the CC.  It was an earlier schematic I had, but similar to the one on the left (advanced thanks to Rob, this is from his website):
http://www.solacity.com/Docs/Wind%20Turbine%20Overvoltage%20Protection.pdf

This is the unit; ours is 24V
http://www.ia.omron.com/data_pdf/data_sheet/k8ab-vs_ds_csm384.pdf

In the normal mode the control should energize a NO relay connecting the turbine to the rectifier.  It is set for Overvoltage; Normally Closed output relay drive mode.


I had thought that terminal 11 was common on this SPST relay, and terminal 12 was normally closed (until the relay actuated on hi-limit).  What I found was that when I energized the unit, the relay switches on after a second or two (T1, I assume), and the terminals close between terminals 12 & 14.  In our case if I switch terminals 12 & 14 it looks to be right, but doesn't appear to agree with Rob's schematic.  My fear is that I've missed something, perhaps obvious to others here.

Our DIP settings are:
1= On, Power On Lock time 5S
2= On, Auto reset
3= On, Relay Drive Mode, NC
4= Off Operating Mode, Overvoltage


I appreciate any help.  My goal was to work thru all these small details over the holiday break. The ice storm here put a serious wrench into those plans.

Regards, ~ks

Darren73

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Re: Voltage Rensing Relay Config - could use some help
« Reply #1 on: December 31, 2013, 06:19:52 PM »
Hi,

Just had a look at the data sheet and the relay is designed as fail safe, ie in the normal operating condition the relay is energised, this should connect terminals 11 and 14. (is your reference to 12 and 14 a typo?)

The relay (terminals 11,12,14) is shown in the de-energised state.

Regards

Darren

kitestrings

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Re: Voltage Rensing Relay Config - could use some help
« Reply #2 on: December 31, 2013, 08:30:57 PM »
Hi Darren,

Yes, you've got it right, and I'd meant to say the switch closes between terminals 11 & 14 when energized.

The theory is that in normal operating mode the relay stays energized and we happily charge the batteries, divert to water (pre-)heat, and finally clip the voltage - right now with our 'homemade clipper' (I hope to add a resistor bank, right now shorting phases) to stay within the operating voltage range of the CC's.  The Omron is intended to be a fail-safe, operating independent of the Classic's.  If there's a component failure, or for whatever reason the voltage gets near the upper limits (~250 VDV, 180 VAC), the NC Omron relay terminals open, and this should open our 'hi-limit' relay.

This saves the CC's, but creates another problem on the tower - because now we're unloaded.  So, I'm trying to have the clipper relay close (using the NO terminals, 11 &12) at the same time.

Got past the (now) obvious problem, but I'm still having problems.  Today, there was no wind, I spun the rotor by hand.  It started free, but then clearly was braking at relatively low rpm.  The Omron was going into alarm mode, and actuating as if we'd past our SV.  I'm wondering if we are operating too low, outside of the low voltage range of things?  My voltage input was on V3 (60-600V AC/DC), but I tried V1 with the same result.  At startup of course we're climbing from -0- to a cut-in voltage of only about 43 VAC.  I'm not sure what I'm missing.

Any ideas.

~kitestrings

kitestrings

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Re: Voltage Rensing Relay Config - could use some help
« Reply #3 on: January 01, 2014, 12:54:49 AM »
I think the problem may be under frequency.  I probably should have picked this up sooner, but the input frequency range is 40-500 HZ.  On our 16-pole alternator, we're only about 12HZ at cut-in, and 33 HZ at 250 RPM.  I'm going to try switching the voltage input to the DC side of the rectifier and see what that does for us.

Oh yah, Happy New Year.

~ks

kitestrings

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Re: Voltage Rensing Relay Config - could use some help
« Reply #4 on: January 01, 2014, 06:50:53 PM »
Well this has become downright frustrating.  This morning I switched the input voltage to the DC input of one of the controllers.  The Classic's have a no load input voltage (with wind) of about 3/4 the battery voltage.  It read about 36+

VDC.  The first thing I noticed was a periodic pulsing/flashing of the alarm light.  It was about 6-8 second intervals, but grew more intense until the relay actuated (relay light comes on), but the alarm LED also lights, then (after T) it goes into hi-limit mode.  I'm wondering if it is picking up a pulse from our Outback for the solar array.

Anyhow, I switched DIP "SW2" Off, Manual Reset, so I could watch what was happening.  Regardless of the input, V1, V2, V3 it seemed to do the same thing.  With varying delay, it is much the same - the relay actuates only to have the alarm state follow right behind.

Unless anyone here has thoughts, I'll probably try contacting Rob, and/or the manuf.  I've bi-passed it for now, but won't be leaving it unattended until I can sort thru this issue.

On a positive note, I programmed the Classics, built my wind curves and completed the local & internet access.  Still no wind of course.

~kitestrings

SparWeb

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Re: Voltage Rensing Relay Config - could use some help
« Reply #5 on: January 03, 2014, 09:21:05 PM »
Your best bet is Rob B., as you say.
I'd like to take a shot at the puzzle, but I can't see much of your system from the photos, and I haven't dealt with a Classic before.  I might not be of much help (I just like to troubleshoot things, kinda compulsively).
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
System spec: 135w BP multicrystalline panels, Xantrex C40, DIY 10ft (3m) diameter wind turbine, Tri-Star TS60, 800AH x 24V AGM Battery, Xantrex SW4024
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kitestrings

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Re: Voltage Rensing Relay Config - could use some help
« Reply #6 on: January 05, 2014, 05:57:07 PM »
This is a copy of what I posted on MS site, but thought I should follow up here:

Well, I finally got the Omron to work as intended this afternoon.  I may let others better explain why this works, but for anyone attempting it, here is what my experience has been. This is the unit that we're using (K8AB-VS3, 24 VDC):

http://www.ia.omron.com/data_pdf/data_sheet/k8ab-vs_ds_csm384.pdf

In the overvoltage operation mode, DIP switch #3 is ON, Operating Mode - Overvoltage; switch #4 is OFF, Relay Drive Method  - Normally Closed.  With the input voltage into terminal #2, the range should be 30-300 V AC/DC.  I'd set the set voltage, SV, to about 76%.  The threshold should then be (300 x .76= ) 228 VDC.  With the hysteresis set at 10% the reset should be 228 - (228 x .10 =) 205 V.  My input voltage today was about 36 VDC (no wind).

Studying the operation sequence and schematic (pg5), we expected that after energizing, and a short delay (T1), that the relay should operate (Green LED ON) and terminals 11 & 14 to be closed; 11 & 12 should be open. 

What I found was that the relay light went out whenever the input voltage was present.  Energized, no reference voltage and the relay light was on, but as soon as a attached the input to V2 the relay went off.  Regardless of the dial settings I could not change the state.  I tried it with a 120VAC source; same result.

I further discovered that, at least with the DC input, that I had the reference voltage across V2 and the A1, the negative terminal of my 24VDC supply.  So, when I removed the "COM" connection - EUREKA - the relay actuated, the LED illuminated, and I could drop the SV slowly down to ~12% and have the alarm flash, then actuate (Red alarm LED illuminates.  Once the alarm state occurred it locked out as I had the manual reset selected.  I cycled thru a few more operations, but end result is as long as COM is not connected it works perfectly.

In our set-up terminals 11 & 14 close to hold the SS relay connecting the turbine under normal conditions.  If we exceed the SV the relay opens disconnecting the turbine, and simultaneously closes the circuit to our clipper relay (via terminals 11 & 12).  Rob's schematic shows this, you just have to note that the drawing is in the de-energized state.

Hope this maybe helps someone else.


~kitestrings

Rob Beckers

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Re: Voltage Rensing Relay Config - could use some help
« Reply #7 on: January 06, 2014, 08:49:55 AM »
Kitestrings, sorry for coming a bit late to the party, I just stumbled upon this thread.

I've built the circuit according to the PDF I've published, and tested that it works. A number of others have as well. The only difference with your implementation that I see is you're using the 24V DC version of the relay, while I've been working with the 115V AC version. There may be a difference, because the spec sheet notes that the DC power supply version of the relay does not have the same isolation between the measurement and power supply terminals vs. the AC versions.

It seems odd that you have to reference the A1 terminal for sensing. The COM terminal is meant to do that, and using it makes it so there's no path between the sensing terminals and the power supply side of the relay (I don't know how Omron implemented this; either the sensing side is literally isolated from the rest of the relay using an opto-coupler, or the leakage current is so low that it doesn't matter). So, the fact that you have to disconnect the COM terminal and use A1 sets off alarm bells for the engineer in me that something else is going on that's yet-to-be-found.

Also note that the specs say that the AC versions of the relay (for the power supply) have 20 MOhm and 2 kV isolation between sensing and power supply terminals. The DC version does not (but nothing more is specified). It seems to hint at a different internal implementation between the two.

As far as I can tell the frequency range of these relays is quite a bit wider than the published 40 Hz. I haven't tested how low it will go, but it seems OK with inputs in the 20 Hz range (from others that have built this). There's an advantage in using AC (straight from the alternator) over DC, in that if the rectifier fails you won't loose your overvoltage protection. If you can, it is also advisable to use the 600V input since in case of a run-away turbine it will handle much higher Voltages vs. the 300V input. I've not tested these relays to destruction, but from what I hear from others it will actually handle well beyond the published range (ie. 300V or 600V) without failure. Published limit is 125% for 10 seconds. Keep in mind too that it does 600V AC RMS (assuming a sine-wave), so that means it needs to handle at least 850V peak on that input. These are pretty robust critters.

None of this is all that helpful for your particular case, and I'm not sure what to suggest here. Possibly taking the relay out of the circuit and testing it with a power supply to see how it responds would be one way to go. What I would suggest for anyone building this is to stick with the 115V AC version of the Omron, as it seems to have somewhat different specs from the 24V DC version, and it's been tested. Still, as mentioned, having to measure between A1 and V2 should not be needed, and something that should be resolved before relying on this to keep your turbine safe.

-RoB-

kitestrings

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Re: Voltage Rensing Relay Config - could use some help
« Reply #8 on: January 06, 2014, 12:53:23 PM »
Hi Rob,

Nice to hear from you, and your timing is actually quite good.  I assumed many of the regular contributors we're either out for the holidays, or dealing with the ice storm.  You must of gotten some of that up your way?

I selected the 24V relay mainly because I have this source readily available (water pump, freezer), and it didn't rely then on the inverter, but I may have introduced some additional factors.  I had isolated the relay from everything on the turbine, powered it up, and then put a nominal 120VAC reference source into it.  With the power supply applied, and no input voltage across V1, 2 or 3 to COM, the relay actuated.  As soon as I connected the input reference, the relay went off; not alarm state, but the Green LED relay light went out, and the relay opened (continuity between 11 &12; 11 & 14 open).  This is what led me to where I am now.

I also noted that the supply voltage "has no polarity when a DC current input is used."  In my case A1 was negative, and I could always see the reference voltage across V2 and A1.

With regard to AC vs. DC you raise a really good point.  And, the main reason I wanted a diode rectifier is that over the years I've had individual diodes fail and lightning (I believe), and they are much easier to test and replace (vs. a potted bridge).  Still, our turbine is 16-pole, so to even get to 20 HZ we're spinning 157 rpm.  My concern is that from start up to cut-in (0 to 12HZ) the relay may not respond.  In our case we'd have the parking brake on, and never get up to speed.  I guess I should check this to be sure though.

It look like the "range" on V3 is 0-600V, even though the "measuring voltage" is 60-600V AC/DC, so I should be able to switch to V3 as you've suggested.  Initially I thought we'd be out of the (low) range since with no wind our reference voltage is ~36 V.  With your inverter protection scheme(s), you probably don't have either low frequency or voltage as a concern?

I may try to contact a rep at Omron, but I wasn't sure how much help they'd offer, being this is a one-off project.

For now, we're running.  It was   p a i n f u l  waiting these last few days for a breath of wind.  This morning we saw upwards of around 1.2 kW, so I'm pretty excited.  For now it won't be operating without supervision.

Thanks for taking the time to respond, and initially for sharing your schematic.  I think it is a sound approach.  Just need to work thru the details in our case.

Kind regards,  ~ks

Rob Beckers

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Re: Voltage Rensing Relay Config - could use some help
« Reply #9 on: January 06, 2014, 07:29:14 PM »
Hi Rob,

Nice to hear from you, and your timing is actually quite good.  I assumed many of the regular contributors we're either out for the holidays, or dealing with the ice storm.  You must of gotten some of that up your way?

It wasn't pretty today: +5C in the morning with rain coming down hard, while the ground was still frozen solid. So anything that wasn't salted became a skating rink (my driveway for one). Tonight -23C, freezing all that water that came down. Luckily we didn't have freezing rain.

I had to drive out this morning; we're building a new warehouse/office and tomorrow is the Big Pour for the concrete slab. Lots of prep work to do. I slip-slided my way over there. (As an aside, if anyone is interested, the new building is a bit different from the usual industrial construction; strawbale walls, passive solar heating, daylighting, PV on the roof, and geothermal heating, see http://www.greenpowertalk.org/showthread.php?t=18748)

Quote
I selected the 24V relay mainly because I have this source readily available (water pump, freezer), and it didn't rely then on the inverter, but I may have introduced some additional factors.  I had isolated the relay from everything on the turbine, powered it up, and then put a nominal 120VAC reference source into it.  With the power supply applied, and no input voltage across V1, 2 or 3 to COM, the relay actuated.  As soon as I connected the input reference, the relay went off; not alarm state, but the Green LED relay light went out, and the relay opened (continuity between 11 &12; 11 & 14 open).  This is what led me to where I am now.

I also noted that the supply voltage "has no polarity when a DC current input is used."  In my case A1 was negative, and I could always see the reference voltage across V2 and A1.

When measuring that Voltage between V2 and A1 you have to be careful, in that the average digital multimeter is 10+ MOhm in input impedance. So the slightest leakage (if there's nothing else pulling that Voltage to a more determined value) will result in a measurement that sometimes indicates a connection that's not really there.

I wonder though, from what you describe, if your relay is on the blink. It just doesn't sound right, and doesn't jive with what I've seen with the Omron relay...

Quote
With regard to AC vs. DC you raise a really good point.  And, the main reason I wanted a diode rectifier is that over the years I've had individual diodes fail and lightning (I believe), and they are much easier to test and replace (vs. a potted bridge).  Still, our turbine is 16-pole, so to even get to 20 HZ we're spinning 157 rpm.  My concern is that from start up to cut-in (0 to 12HZ) the relay may not respond.  In our case we'd have the parking brake on, and never get up to speed.  I guess I should check this to be sure though.

Let me know what you find out about frequency range. Not knowing what the internal circuitry is like, I (still) would think that they would not design this to be all that sensitive to frequency. As long as the signal is fast enough to avoid chatter of the relays (and those are fast, so at least 10 Hz I'd think). What may well be the case is that its Voltage sensing is not as precise when the frequency is out-of-spec, but that doesn't really matter in your case.

If anything the low Voltage during startup should not trip the relay (as will be the case when you come off the brake, at 0V output), so the relay should switch away from the dump load and on to the inverter.

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It look like the "range" on V3 is 0-600V, even though the "measuring voltage" is 60-600V AC/DC, so I should be able to switch to V3 as you've suggested.  Initially I thought we'd be out of the (low) range since with no wind our reference voltage is ~36 V.  With your inverter protection scheme(s), you probably don't have either low frequency or voltage as a concern?

The concern is on the other end, for overvoltage. So, no, on the low end it doesn't matter as long as the Omron recognizes it as "undervoltage" and switches so 11 and 14 are connected. No precision is required on the low Voltage end, it just needs to measure the disconnect Voltage on the high end correctly.

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I may try to contact a rep at Omron, but I wasn't sure how much help they'd offer, being this is a one-off project.

Never tried. Good luck!

Quote
For now, we're running.  It was   p a i n f u l  waiting these last few days for a breath of wind.  This morning we saw upwards of around 1.2 kW, so I'm pretty excited.  For now it won't be operating without supervision.

Isn't that always the case!  ;)

Quote
Thanks for taking the time to respond, and initially for sharing your schematic.  I think it is a sound approach.  Just need to work thru the details in our case.

Kind regards,  ~ks

Good luck!

-RoB-

kitestrings

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Re: Voltage Rensing Relay Config - could use some help
« Reply #10 on: January 06, 2014, 09:47:53 PM »
Rob,

Yes, this weather thing is something else.  We had a similar day here, and about eight days around Christmas where we couldn't seem to keep anyone's lights on.  A bit earlier electrodaddy shared this pic/post (near Toronto):
http://www.fieldlines.com/index.php/topic,148025.0.html

Your building plans are fantastic.  I'm going to share this with my son, Mitch.  He did the CAD (I think it is actually a program called Ribit (Rebit, sp?) drawings for our build, but his daytime job is architecture.

I'll post any updates as I learn more, but you've given me some things to chew on.  I don't think the relay itself is faulty, unless it was out of the box.  It only recently has had any sort of use, as we've had no wind 'til today, and I have a 1A fuse protecting the supply.  There may be something unique to our configuration that will explain things.

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If anything the low Voltage during startup should not trip the relay (as will be the case when you come off the brake, at 0V output), so the relay should switch away from the dump load and on to the inverter.

In our case there's no inverter involved.  We have "hi-limit" SS relay connecting the turbine to the rectifier, and a second relay that engages the dump/clipper.   I hope to move the latter to a load bank, as I've never been a big fan of shorting the windings (that you've otherwise designed to efficiently remove heat).  And, it's unnecessarily abrupt IMO.

I'll have to check the frequency issue, but you've captured my question of whether the relay would operate soon enough in low rpm start-up to actuate relay (before the cogging/braking effects things).  It should be pretty easy to test.

Again thanks for taking time for your response(s).  You're expertise and experience here is very helpful.

Kindly, ~kitestrings

OperaHouse

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Re: Voltage Rensing Relay Config - could use some help
« Reply #11 on: January 07, 2014, 02:00:01 PM »
Just because it isn't isolated doesn't mean there will be a problem..  Says you can use either input so it is differential.  With a long wire run it could be picking up RF.  I would try something like a corcom power line filter on it with a ground connection.

kitestrings

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Re: Voltage Rensing Relay Config - could use some help
« Reply #12 on: November 25, 2014, 04:00:34 PM »
This is older post, but I realized that I never followed up on it.

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I wonder though, from what you describe, if your relay is on the blink. It just doesn't sound right, and doesn't jive with what I've seen with the Omron relay...

Rob was right.  I bought a second relay; identical make model, and it works as intended.  The original relay, new out of the box, acted oddly from the start, but since it was new I'd just assumed that I had some other problem.  The original relay seemed to have lost the isolation between the DC negative and the "Com" terminal.

I had set them up side by side in a simple test application. Power (24VDC) to the unit, with an SV setting of 20%, and a probe on V1 (20-200VAC/DC), we would expect the thing to trip above (200 x .2 =) 40V.  I could choose a voltage above or below this on our battery bank.  The new one worked fine.  The original unit would drop out as soon as I connected the “Com” terminal.

The nice thing is that with the new unit I'm able to monitor the upper range of the 3-phase AC voltage from the turbine.  As Rob had pointed out this is better if the rectifier, or a diode(s) should fail.  In our case we have two isolated DC inputs, from two separate bridges, so there was no way to protect both controllers on the DC side.

Rob Beckers has a number of variations of this protection scheme for his grid-tied Aurora inverters.  We're using one to hopefully protect our CCs.  It seems like inexpensive insurance.

~kitestrings