# 3-Phase 60kw Kohler Generator Pains - Voltage Issues



## 60kwOwner (Feb 1, 2020)

Hi guys! Start off by saying reading around the forums has helped better my understanding of these tools.

I recently was given this beast of a generator, Kohler 60kw Diesel. 

She starts up fine, as long as there is diesel no problems! The problem comes from voltage. For the past couple of days I have been trying to diagnose and fix the issues.

Whenever I test with the multi-meter on any of two leads I get a large fluctuation between 70-130 volts. Same thing when measuring from one of the 3 leads to ground.

First was to clean up some nest that was inside the control area, apparently it had fried some wire on one of the relays. I fixed that but it didn't solve my voltage problem.

I played around for a bit testing all the relays and cleaning her up but didn't find a solution until I thought to play with the throttle a bit. If I run the throttle full blast I am getting the full 220v from probing two of the 3 leads on the breaker and 120v when probing from 1 of the three leads and ground. 

You could say problem solved, however this will consume a lot of diesel, produces a lot of white smoke, is much much louder than any lower throttling/idle and previous owner said that he never needed to full throttle it for proper voltage. That last bit I suppose he could have been mistaken....

Is it possible the voltage regulator is toast?

I found a replacement online, however it is pricey.

https://www.colburnpower.com/kohler-generator-parts/kohler-part-b-269735-voltage-regulator.html

Any input is welcomed as I am just learning about this beast and most of my electronic knowledge is in low power DC circuit building, arcades etc.

Thanks!


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## iowagold (Jan 22, 2020)

please post the serial number and model number.
also post the numbers rating plate.

is this a 240 volt or a 208 volt??
also the knob on the pot for the voltage adjust is missing..
is the pot or voltage adjustment rheostat ok?
I am thinking at first thought this might be a 208 volt unit..

see the install setup manual for this unit...
there maybe a buss bar setup to select the voltage and hz.
most of these were for industrial places.


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## 60kwOwner (Feb 1, 2020)

You are correct that it is a 208v generator. 

I have no idea teh model number, could not find anything like that. The motor (not engine) says Kohler Electric Plant, there is a plate on it with more info. I will get a picture of it tomorrow morning for you. I believe it says 1600rpm. 

I have not checked the voltage adjustment pot, I have turned it back and forth with no visible change on the multimeter.

Thanks a lot for helping, quick response so far!


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## 60kwOwner (Feb 1, 2020)

Here is a picture of the reading from the main panel I installed on it


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## Melson (Dec 8, 2019)

This is an 1800 rpm set: 1800 is its rated speed; 60 hz rated frequency. 
Let's start with the good news: These old mechanical relay sets are relatively simple, durable, can withstand a lot of malfeasance and abuse, and many times can be diagnosed just by looking at things.

Now, you state, "full blast". Not sure what this means. Typically, these sets have a governor and a fixed speed; some don't even have a throttle handle or knob or any other means of adjustment. Most of these sets -not all, but most- accelerate to rated speed when started, there would be no 'idle', per se'. You should see the frequency meter centered on 60 hz as confirmation that the engine is running properly.
If the engine is running too slow the voltage regulator will not work properly until the engine is running at a speed close to 60 hz - let's call it something above 52 hz.
In the photo where you have the engine running, and showing a low voltage reading on your DVM, you'll notice that the frequency meter (upper right hand corner) is off-scale at less than 55 hz. You can't test the voltage regulator until you get the speed somewhere on that meter. 

IS that what you mean by "full blast"? That you have to set some throttle at 'max' in order to get 60hz?


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## Melson (Dec 8, 2019)

also, it might be helpful to include a photo of the throttle you are adjusting. The injector pump, too.


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## 60kwOwner (Feb 1, 2020)

Here is a few more pictures


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## 60kwOwner (Feb 1, 2020)

Here is a few more pictures, thanks.

208 line is showing around 120hz, but is jumping around. The 110v line is showing 62hz steady.

That has to be bad right? All the electronics I am trying to run are 50/60hz 110-240v

I managed to adjust the throttle to where it now produces steady voltage around 75% throttle.


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## 60kwOwner (Feb 1, 2020)

Here is a video of the Hz fluctuation


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## iowagold (Jan 22, 2020)

do you have a hand held contactless tach yet??
you need one to look at the rpm on the diesel part...
put the reflective tape on the crank balancer.

cool these days as they are cheap!!

last I knew these were " fixed rpm" to get the hz.
they are adjustiable and have a electrical to mechanical governor to keep the rpm steady for the load changes.
but the hz needs to be right about center of the 60hz...

last I knew unless you are setup for 208 on your L1 to L2 load you need an accy transformer to change that to
single phase L1 125 vac to neutral L2 125 vac to neutral and L1 to L2 as 240 vac...
maybe something like this https://store.maddoxtransformer.com/products/240-delta-208-y-120?variant=45588273993

but on most late trailer units I have worked with they also have different taps for output
and shorting bars to "program" or "select" the gensets outputs.

are there any printed paper tags inside the side covers?

the tag on the generator alternator or "head" is just for that unit..
but some times unless the head has been swapped out you can track that back to the gensets model and serial number with a call to the mfg.
on the older stuff it is all "hand check" 
now days after 2006 mfg most of it is all in a data base some where...
unless the mfg had folks enter the data for each model and serial number if they were all option units during production.
back then most of the larger units were just that!!
made to the clients specs on demand...

yea we need to know more on the head wiring...
I suspect it is a 208 Y 3 phase style..
but it could have the correct taps for 240.


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## iowagold (Jan 22, 2020)

here is the mfg site Kohler Power | In Power. Since 1920.
you might be able to contact them with the data off the head for a wiring diagram..
and the build sheet that might have the serial number for the unit.


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## Melson (Dec 8, 2019)

There's many unknowns as you present. Such as:
Where are your meter leads attached? 
Is the output ckt breaker closed? (if not, you need to probe directly on the alternator leads before accurate readings)
Is this a brush or brushless alternator?

Here's what I can deduce from the limited info: This is a 208 vac, 3-ph, 1800 rpm set. It sounds like the engine is running at least close to speed.
Here's what I suggest: Get the engine to run at 60 hz as indicated on the meter panel. Next, put the handheld meters away for now. Instead, trust the panel voltmeter (top left) to confirm output voltage as you rotate the selector switch between all positions.
Report back your findings.

Again, if you are probing the output leads withOUT the on-set breaker being closed your digital voltmeter will give incorrect values that tend to bounce around. Especially the frequency, which, in my experience, will tend to read in multiples of the base frequency.

EDIT: looking at one of your photos I notice the onset ckt bkr is in the open, or off, position. I also notice the top output leads have been cut. So, where are you probing with your handheld meters? (hint: you need to be probing the bottom breaker leads, those that are coming from the alternator.)
One more thing: Would you happen to have a Fluke digital meter,or equal? Don't mean to disparage your equipment, but, I've seen some strange "problems" that got back to the measuring equipment being used. I don't that's the case here, but, for now, at least, I'd rather trust the onset metering. We can get back to your handheld meters later.


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## KRE (Nov 29, 2011)

OP You have been given some miss information. The no load speed for that unit should be 62.5 hertz as that engine governor is at best a 5% droop. Until you start at the beginning you will be running in circles. Units that far back may or may not have an under frequency roll off, built into the Voltage regulator. That should be a 6 coil stator which will make many different voltages be they single or 3 phase, depending on how it's terminated. When working on anything always split the system on half, if you have what you need mid way the issue is down stream, if you don't have what you need at ;mid stream why would you expect the remaining to operate properly? If it's not at that mid point split that point again. Test don't guess. I can not see all of photos/links that you posted as I will not allow all the scripts required to run on my computer, however I did see enough of the you tube video to see what your working on.


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## Melson (Dec 8, 2019)

@KRE, no mis-info; the set isn't yet running under load. We can get to the finer details, such as droop and wiring configurations, later.
But for now, we're simply trying to understand the OP's complaint and what would cause it. #1 in my mind is to get the set running at close to rated speed, then start probing from there.
The good news is that from the video the engine sounds healthy. Also, at just 600-something hrs on the hour meter this is a relatively low-time set.


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## KRE (Nov 29, 2011)

Melson said:


> @KRE , no mis-info; the set isn't yet running under load. We can get to the finer details, such as droop and wiring configurations, later.
> But for now, we're simply trying to understand the OP's complaint and what would cause it. #1 in my mind is to get the set running at close to rated speed, then start probing from there.
> The good news is that from the video the engine sounds healthy. Also, at just 600-something hrs on the hour meter this is a relatively low-time set.


Does not matter wither it's running no load or full load. If the prime mover is not operating properly the Alternator is never going to operate correctly. Trying to solve an issue by jumping around in a system never yields timely or proper results. Just a little I leaned in the 45+ years of working in the EPG (electrical power generation) field. The basic principles of EPG are the same be it a rope start, large resip, steam or Gas turbine set.


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## Melson (Dec 8, 2019)

KRE, in this case it does matter because his issue isn't one of loading. Do we even know what the issue is, for a fact? 
The first thing I want to know is the engine is close to rated speed - doesn't have to be perfect 60 hz. 62 or 58 is close enough. agree? 
Next thing I want to know is where is the OP probing? He's never really said.
Lets be cognizant of the possibility that the OP doesn't seem to be experienced, so we should not be ripping & stripping - one thing at a time, which, to me, is to understand the basics.
By the way, 42 years in the power field here, too. Large and small AC & DC plant; batteries; inverters; converters; ac & dc switchgear; gas, diesel and gas turbine prime movers; analog and digital controllers.
I'm a master of none, certainly no expert in any. But, I've been involved with a lot of stuff and try to be helpful.


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## KRE (Nov 29, 2011)

Melson said:


> - doesn't have to be perfect 60 hz. 62 or 58 is close enough. agree?


Do not agree as I do not know where the UFRO knee point is set, should it have one. Nor do I know the percentage angle that it has. It could be found quickly with a meter or scope. Again if the prime mover is not up to snuff, everything down stream will not be either. I have seen too many people chasing their tails an waiting time/money over very simple issues, like this. The Kohler excitation system is unlike most others, as it uses an FR activator an a PMG power supply. If this unit is like I think it is, all the voltage reg does is turn on an off a single LED that adds or subtracts light to a rotating photo board. That broad adds or subtracts voltage to the FR activator SCR's, that power the main rotating fields. The Sensing leads just supply voltage to the voltage regulator to allow the reg to add or subtract battery power to the LED. It is a closed loop system which is different than any other PMG style gen ever made. The magnets are stationary an the exciter rotor just spins inside to supply the FR activator.


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## Melson (Dec 8, 2019)

@KRE, ok


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## 60kwOwner (Feb 1, 2020)

"Lets be cognizant of the possibility that the OP doesn't seem to be experienced, so we should not be ripping & stripping - one thing at a time, which, to me, is to understand the basics."

This is correct. Doing my best with the limited knowledge I have on generators of this kind. I am enjoying these lessons though. You guys are great.

I seem to be closing the issues that pop up so far. I am no worried about the fluctuating "hz" readings I am getting. I do not want to damage the Ballasts I am running.

I will take another video in the morning, probing from all points, using both the true rms meter and the smaller one to provide more clear info. This machine is a beast with very few operating hours on it and I would love to know all about it.

The load will be approximately 30k watts. I was also planning on using a "V2 AutoGen 12v auto start generator controller." to remotely start it or on timer as needed.

Thanks guys


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## 60kwOwner (Feb 1, 2020)

I forgot to mention that there is white smoke coming from the exhaust, not very thick but noticeable. From what I have read, this is not a good thing to see. How should I address this? Thanks again


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## KRE (Nov 29, 2011)

Test the voltage at the top of the main load breaker. If it does not have a load breaker test at the stator output leads. Are you sure it's white smoke instead of a very faint light blue? Older units that have been ran on Low sulfur fuel w/o a lubricity adder will wear the cam/s & barrels an plungers in the pump. This allows the injection timing to retard. The timing can be reset easily by advancing the injection pump. That said it may not be retarded timing at all it could be what is normally call wet stacking. This cause is do to lack of load an as that engine has keystone rings they may not be seated to the cylinder walls. This can be corrected by placing all the load on the unit it will stand for a few hrs. If after a few hrs the smoking starts to lessen, place more load on it an run a few hrs more. Diesel engine Keystone ring designs requires higher cylinder pressures than std straight cut rings to seal against the cyl wall. I have had to load some engines for over 24 hrs to being them back to life. Many would not pull 30% of rated load prior but were at 100% at the end. Two stroke diesels are the worst as they cool more rapidly that 4 strokes. Many people disassemble a wet stacking engine an re-hone the cyl walls but I have found loading them up is best in the long run. If your load allows the until to wet stack all the time a baffle/restriction plate can be added to the exhaust system to hold the heat/pressure on the rings. This is now commonly found in 2 strokes that were over sized for the load. HTH


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## 60kwOwner (Feb 1, 2020)

Thanks for that information. Are you saying that I should put a heavy load onto it? Something close to its 60kw?

Here is a video probing around more below the main breaker, checking the 208 and 120 hz readings as well as walking around and showing parts of the machine in case that is helpful or something is off.


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## KRE (Nov 29, 2011)

Most everything I see is normal except the crankcase vent tube is missing, your DVM an the panel meters read differently(thats normal as well in some cases) However one thing I do see that may or may not be an issue is it appears at around the 2.26 video mark the hole in the bottom of the panel seems like there is a spark jumping? Could be the lighting an just something moving? The speed is low for total load but if 30KW is your target load I'd bump the Hertz to 61.5-6 if it were I. If your load is a 208 3 phase load your good. If your load is otherwise you will need to adjust the voltage or reconnect the stator winding's to achieve same. If your load is single phase you have to reduce the total capacity by 33%. If your just going to crank the voltage up to 220 phases to phase which will give you a 127 phase to neutral to power a single phase home/shop load make sure the load does not exceed the single coil stack rating. Everything rated for 240 will run fine on 220, the kicker is if your load is a 3 phase 120/240 delta, you may need the 208 leg to neutral. You load requirements will dictate what you need to do.


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## ToolLover (Jan 13, 2020)

So, after reading the experienced replies I am curious, is it possible that the commutator could us a little polishing as a first easy place to begin?


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## 60kwOwner (Feb 1, 2020)

I believe it is blue;






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The load I will be putting on it is single phase 120v and 208v at around 30kw-40kw of power usage. This will mainly run Digital Ballasts that are fine with 208v and some 120v appliances like heaters/pumps and things.

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I found this on the crankcase vent tube;



> A positive crankcase ventilation (PCV) valve system vents excess pressure from inside your engine. This is done using a PCV valve and crankcase breather hose. The hose sends crankcase gases to your intake to be burned in the cylinders.


Is this what you mean? If so is it important? If so, how to fix it 

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I see the spark reference you are talking about, I can't tell either. I will take a look tomorrow at that.

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> I'd bump the Hertz to 61.5-6


How?

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> If your load is otherwise you will need to adjust the voltage or reconnect the stator winding's to achieve same.


How can I achieve this as I stated the load I have is a single phase load.

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Once again guys, thanks for the fast responses and help with this. I am a mere mortal in this field and trying to keep up. So I apologies if I don't know the terminology or how to achieve things involving modifying motors like this without simpler directions.


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## 60kwOwner (Feb 1, 2020)

After doing some more research it looks like these types of generators have an easy way to reconfigure them;



> Larger generators commonly have 12 leads from six coils and all the wires come out of the generator making it easier to configure the generator in a variety of ways as follows –
> 
> • Connecting the coils in series will convert the generator to a single-phase one.


After thinking about it, there are a lot of wires coming into where the large breaker is sitting. They are all labeled with numbers and then it looks like they are going into the different posts of the breaker.

https://pasteboard.co/ITdCj7u.jpg

The white taped ones are all going to ground, I was poking around when I first got the generator. =)

I am assuming if I want to switch it to a single phase generator I would need to re-arrange these wires to a certain configuration to make it work?


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## KRE (Nov 29, 2011)

You can not achieve a 120/208 single phase load w/o leaving the unit wire for 120/208 3 phase. You can wire it dog leg or double delta an get 120/240 single phase but if you turn the phase to phase down to 208 your phase to neutral will be to way to low. Plus if you try to pull 40 KW set up like that you will burn up the stator. Crank case breather tube is just a rubber hose that needs to be connected to the breather cap on the valve cover. There is no PVC valve on that engine. Hertz adjustment is via the injection pump adjustments. IIRC your's were sealed with red tattle tale paint, one is the high idle (speed stop) The other is the speed adjustment. You may have to back one off while to screw the other in, depending who did the pump. There should be a little play in the fuel control lever an as you move in (it has a spring attached internally) the Hertz will increase or decrease as you make the adjustment. This whole task takes about 20-30 seconds. What you have is a 12 lead stator, which will make any US voltage at 60 hertz or any voltage that runs with a 50 hertz machine. For US it will make 120 delta 3 phase 120/208 3 phase 208 delta 3 phase 120/240 high leg delta 240 delta 3 phase 277/480 3 phase 480 delta 3 phase 120/240 single phase. It will make MANY, MANY other voltages like 347/600 3 phase, but they are more uncommon being for specialized applications, most not in the industry will never deal with or see. The 347/600 3 phase is common in Canada though. Just a FYI there are many units running that are 277/480 3 phase Y connected yet we are also pulling 240 delta off them w/o transformers as we center tapped the stator for this which saves the cost of a transformer. Doing this is easy but you have to run the numbers so as not to over load the first 3 coils in the stack. The unit you have many make your florence lamps flicker, even when the unit is operating to design spec. That is caused by the type of excitation system Kohler uses an when using some lamp ballast designs. Nothing to worry about at all. Remember those lamps at 60 hertz turn on an off a 7200 times per minute an the interaction of the FR activator make them think there is not power. Newer design Ballast, will not do that. HTH


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## 60kwOwner (Feb 1, 2020)

Thank you KRE.

That is unfortunate to hear. The only solution then is to get a 3 Phase Breaker and load balance the lights over the three lines?

That or of course using a 3 Phase to Single Phase Transformer. That would cost a pretty penny however.

Anything I can do about the blue smoke?


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## KRE (Nov 29, 2011)

60kwOwner said:


> Thank you KRE.
> 
> That is unfortunate to hear. The only solution then is to get a 3 Phase Breaker and load balance the lights over the three lines?
> 
> ...


Now you have me puzzled with that response. That unit will supply what ever power you need. On single phase you have to de-rate it to 40 kW max, an you said your load is only 30-40kw so I don't see an issue there. Also if your load is rated for 120/208 you can still supply it with 120/240 single phase an it will still be as happy as a clam, if you set it up properly. Please explain where I led you wrong? I am confused? The only issue you would have to deal with is if you have an automatic transfer switch that uses a in-phase monitor an it's not set properly for YOUR application, but that's a none issue as I can walk you threw setting it properly once I know who made the switch. I think you may have took something out of context some where, but that unit will work for you. Please explain where I led you to believe it won't so I don't make that mistake again some where.


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## 60kwOwner (Feb 1, 2020)

Thanks for that, I appreciate being walked through things I don't fully understand.

I understood that if I run it as single phase as is on the two lugs intead of using all three I could potentially damage something like the stator....

Or are you saying it is completely fine as long as I stay within 2/3rds of the rated 208 amps?


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## KRE (Nov 29, 2011)

It will be fine on 120/240 single phase as long as you do not exceed 167 amps phase to phase. Wired that way the engine will still pull 60KW but on single phase you are not using all the coils there for you have to reduce the sets rating to 40KW max so as to not over load the alternator stator windings. You can leave the unit wire for 3 phase an just pull 208 power from two legs at only 66% max set rating. However the set will be running so unbalanced you can cause issues down the line. If you only need single phase, I would recommend wiring it as such, an be done with it. You can change it to single phase very easily an a pro can do it in less than 10-20 minutes total time depending experience level.


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## 60kwOwner (Feb 1, 2020)

Bah, now I am even more confused!

Right now I have a single phase panel wired up On lugs 1 and 3 and ground, leaving lug 2 empty which nets me 120/208v.

Are you saying that I can wire the generator itself up to single phase 120/240v? I understood that wasn't possible from your previous message.

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> If you only need single phase, I would recommend wiring it as such, an be done with it. You can change it to single phase very easily an a pro can do it in less than 10-20 minutes total time depending experience level.


I want this yes. I wouldn't have any issue wiring something up if I have the diagram showing how or which wires to go where to make this happen.

Thanks for sticking with me, I am sure it can be frustrating dealing with someone new to these things.


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## KRE (Nov 29, 2011)

60kwOwner said:


> Are you saying that I can wire the generator itself up to single phase 120/240v?


Yes that is what I have been saying. Research The wiring connections on line via the model number or call a Kohler dealer for the operating/installation manual.


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## 60kwOwner (Feb 1, 2020)

Thanks, 

Can't find the model number anywhere. Any idea where to check for it?

Maybe someone here knows?


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## 60kwOwner (Feb 1, 2020)

Here are two pictures of the Motor and the Engine serial plates. Can these be useful in identifying the model number of the generator for rewiring?


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