Thread Number: 78407  /  Tag: Modern Dryers
Fix or Replace?
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Post# 1024329   2/11/2019 at 19:01 by blench (East Texas)        

We bought all new Whirlpool appliances when we built our house 7 years ago. We have not been overly impressed. The dishwasher (not me, but the electric one) had issues at about 1 year -- blowing thermal fuses. I would replace them and they would last about a year then blow out again. After about 4 replacements, I just replaced the whole unit.

Today the washer died. (Whirlpool Duet model WFW94HEXW2). It is throwing an error code F6E1 (communication error between MCU and CCU). I went through the troubleshooting and finally found that the MCU was burned up. I pulled the MCU and it definitely has visually blown components on the board.

Now... do I buy another MCU (about $300 at random google)? Or am I likely to find another cascading failure where the MCU died because of a motor problem?

Or do I just toss the whole thing and replace it entirely?


Post# 1024332 , Reply# 1   2/11/2019 at 19:16 by Pierreandreply4 (St-Bruno de montarville (province of quebec) canada)        
depends on the age of the washer

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it depends on the age of the washer if its repairable have it repaired after having a service tech check it out if the service tech say its beyond repair then replace but the first step would be to have your washer check by a service tech

Post# 1024334 , Reply# 2   2/11/2019 at 19:42 by DADoES (TX,†U.S. of A.)        

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My aunt's Duet of the same model blew the motor board last year.† I diagnosed the problem, ordered the part from SearsPartsDirect.com (they paid so I don't recall the $ but it was less than now), uncle did the replacement when it arrived.

Part Number W10374126 --> WPW10374126

There are several new choices on eBay $169.99, $171.99, $189.95.† Also probably some used choices if you feel comfortable going that route.

Can also have it repaired via CorecentricSolutions.com $150 + shipping & taxes.


Post# 1024336 , Reply# 3   2/11/2019 at 21:18 by combo52 (Beltsville,Md)        
WP Duet, Fix Or Replace ?

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Hi, How many loads a week has this machine washed a week on average and have you ever let it get smelly and or moldy ?

 

If it has done much more than 10 loads a week and or gotten fairly smelly and moldy it probably does not have that much more life in it.

 

In any case if you fix it either get the board rebuilt or buy a cheaper board, I would not spend $300 just for the part.

 

As a WP tech I have never seen a WP built DW go through 4 TFs in four years, are you sure the leads were replaced with the heaver leads when the first TF failed, if they are not replaced they will fail again and again.

 

John L.


Post# 1024337 , Reply# 4   2/11/2019 at 21:23 by IowaBear (Cedar Rapids, IA)        

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No experience with Duets, but the motor control board failed on my Maytag Neptune a couple of years ago.  I bought a used one from eBay for around $70 and it was good as new. 

 

Service calls and new parts are very expensive.  Going that route makes it harder to justify repair.

 


Post# 1024346 , Reply# 5   2/11/2019 at 23:09 by Joe_in_philly (Philadelphia, PA, USA)        

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This thread has me wondering if blown electrical components are ever caused by dirty power or line surges. If so, that might explain why some people have more problems than others.

When I got my Kenmore HE3t and matching dryer (over 15 years ago), it was suggested that they be plugged into surge protectors, so I did. Is that necessary, or do appliances have built in power protection components?


Post# 1024353 , Reply# 6   2/12/2019 at 05:47 by Superocd (PNW)        

I have my Kenmore (LG) front loader plugged into a surge protector. At $20 for a decent surge protector, it's cheap insurance but you have to remember to replace them every 2-3 years, they do NOT last forever and do wear out from having to sustain spikes after so long. I simply use the kind that sit directly on top of the outlet.

I also have my Whirlpool DW and refrigerator on a surge protector since they both have control boards, and also have one on my Panasonic countertop micro. The only appliances I don't have on a surge protector are my range and dryer. The range has a control board of course, but is 240v/50A and would need surge protection at the breaker level, which is something I've considered implementing for the whole house eventually. The dryer is a BOL Kenmore (Whirlpool) and does not need a surge protector since it is old school and without control boards.



Post# 1024355 , Reply# 7   2/12/2019 at 05:55 by Superocd (PNW)        

I forgot to add that yes, most appliances typically have surge protection built in but not in the way you'd think (protection of the machine's components). It's more of a fire prevention thing since a fire is bound to start if tens of even hundreds of thousands of amps pass through the tiny traces and board components. Fuses are in the first line of defense but onboard surge suppression a secondary means of defense, particularly with arcing/crossover.

Typically the onboard surge protection does its job (prevents a fire), but the surge protection circuit is almost always integrated in the very board it's "protecting", and the board is dead since the circuit is open. Computer power supplies, TVs, etc. are the same way.


Post# 1024369 , Reply# 8   2/12/2019 at 09:35 by blench (East Texas)        

combo52: We definitely don't do 10 loads a week. We are a 2 person household. No smell, but we do get flecks of black mold. We always leave the door/soap dispenser ajar to try to avoid this, but it appears to be happening anyway.

As to the DW: Yes, I replaced with the heavier/longer leads that came with the part. I believe there were other issues going on. The fuse blows got closer and closer together each time and by the end the wiring harness was clearly turning black in some places. Without any real diagnosis, I was guessing the main board was going bad. (See next item below)

---

Joe in philly: We have long wondered if dirty power was an issue. I *know* we have dirty power. I'm a computer nerd. I track how many drop-outs/spikes my UPS sees. It ranges from 2-10 a day. Some are predictable and happen the exact same time every day (like when the morning grid switching occurs). I have a whole house surge protector and surge protectors on all 120v appliances... but that won't help with the drop outs.

Since moving in I've had issues with: This washing machine; dishwasher; replaced HD in Tivo; replaced power supply on Tivo; replaced multiple computer HD; replaced main board in garage door opener. I'm probably forgetting a couple. (Tivo and computers and networking are now fully covered by UPS with no unexpected failures since. I've replaced a few drives since, but they were old enough that they were not unexpected.)

---

And doing a more exhaustive search, I do find the part for much less. I am seeing it for around $180 now... which is feeling like probably worth gambling on. I'd prefer to just put in an older Maytag/Speed Queen, but we are on a septic and I don't know how much water I want to be pushing through the system.


Post# 1024410 , Reply# 9   2/12/2019 at 19:19 by Joe_in_philly (Philadelphia, PA, USA)        

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Superocd: Thanks for the explanation about surge protection. Now I am thinking I should have surge protectors on other appliances!

Blench: I am sorry to hear about all the items you have had to replace. It sounds like youíre doing everything you can do to prevent problems.


Post# 1024693 , Reply# 10   2/15/2019 at 11:45 by kb0nes (Burnsville, MN)        

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Surges are often blamed, but not often the real cause of electronic failures. Certainly wasn't the reason the DW thermal fuses were failing.

A whole home surge protector isn't a bad idea, but lacking a nearby lightning strike you are very unlikely to have a true surge related failure.


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Post# 1024701 , Reply# 11   2/15/2019 at 14:39 by Lorainfurniture (Cleveland )        
Not accurate

As a servicer I can tell you 100% the morning after a lightning storm my voicemail is lit up. I will agree that surges are very rare, (voltages north of 140v, or 260, but most boards fail due to brown outs, or when a line on the pole touches and sends 120v through the neutral. You wouldnít believe how many people have the polarity reversed on their outlets.

Boards that live in a cool dry environment and get fed clean power will basically last forever. Or at least until the solder shrinks and cracks.


Post# 1024702 , Reply# 12   2/15/2019 at 14:48 by henene4 (Germany)        
Polaritys reversed

Hmm, yes, verry dramatic on AC, sure!

Post# 1024727 , Reply# 13   2/15/2019 at 21:18 by Lorainfurniture (Cleveland )        
@henene4

Im not sure if you are kidding or not, but reverse polarity is a death sentence for a board. Specifically for the capacitors.

Post# 1024730 , Reply# 14   2/15/2019 at 22:00 by combo52 (Beltsville,Md)        
Appliance Board Failures

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Polarity is either reversed or not and there are a few appliance boards that do not function properly with reversed polarity, mostly spark ignition boards on gas ranges, BUT it does not hurt the board, you just have to correct the polarity and the range will work properly.

 

I have never seen any big increase in calls after lighting storms and we get some really serious lighting here in summer storms.

 

Brown outs are very uncommon and will not hurt boards.

 

All appliance boards have all the surge protection they need built in, A surge protector is most unlikely to ever help, if you have a serious surge they are not going to help. A large whole house would be far better than a cheap plug in protector.

 

70% of appliance board are caused by combinations of excess heat, moisture or other liquids seeping into areas they should not be in, cheap membrane touch controls, high current causing solder connections to fail, cheap capacitors and other components that are just not durable enough.

 

John L.


Post# 1025050 , Reply# 15   2/18/2019 at 19:21 by kb0nes (Burnsville, MN)        

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I like when polarity reverses on AC, it seems to do it a lot. From what I have seen it seldom causes problems ;)

Post# 1025056 , Reply# 16   2/18/2019 at 20:57 by Lorainfurniture (Cleveland )        

Next time you guys talk to anyone who knows anything about electronics, ask them what would happen if you install a capacitor backwards.

Reverse polarity will kill a board , so will: low voltage, high voltage, dirty voltage, L to N, moisture, excess heat, ROACHES, and much more.


Post# 1025068 , Reply# 17   2/18/2019 at 22:48 by henene4 (Germany)        

If you are talking DC supply sure.
If you are talking polarized capacitors, sure.
However you can't really install a non-polarized capacitor backwards, especially if the verry definition of "backwards" usually changes 50 or 60 times a second.
(Small, almost insignificant errors in the stated frequencys are part of normal operation of this system and can not be fully avoided, we ask for your understanding.)

Moisture will cause short circuits, duh.

Don't see how roaches can kill a soldered solid state piece of equipment though.
They might eat away at wires, but honestly, if a roach has enough time to eat through a wire, I would be more worried about why roaches a crawling through your electronics for so long without you either noticing or taking action.

Of course to high voltage kills components, that is the verry idea of a power surge.
How low voltage is supposed to harm equipment I don't really see though. Like, you mean that less power applied to it then it's supposed to handle breaks it?
Like, having a shelf that perfect well handles all the books sitting on it for years suddenly collapse after you picked up one of the books.
Sounds perfectly logical, sure...

"Dirty voltage" dosen't exist in DC supplies really.
I mean, it can, if the voltage suddenly and unexpectedly shoots up or reverses polarity.
Wait, fluctuating voltage that reverses polarity periodically, that sounds familiar, right?
(Yeah, of course hooking up a DC powered device to any AC supply will cause problems, but running an AC powered device on DC most likely will not work either...)
On AC it is indeed true that noise on a supply can reduce the lifetime of certain electrics.
That is why stereo systems, computers and actually a lot of normal appliances have line filters.
But as you know electronics so well you knew that already.

Heat of course can kill components.
Like, why do you think computers have elaborate systems designed to keep a component from overheating (aka CPU cooling).
Even some smartphones of today have heat pipes to spread the heat from the CPU over a bigger area to dissipate it more effectively.



And of course just holding the 2 sides of a supply together will cause a short circuit.

Like, your trying to tell me that the verry definition of a short circuit causes a short circuit situation and the resulting consequences/damage to arise as if I never visited 5th grade physics.

Actually, to make this even worse, no, just grabbing the life and neutral of a random socket and sticking them together will most likely result in basicly no damage to anything in the room.
The short circuit causes a huge current surge (I=U/R, U being your line voltage, R your wire resistance) turning all the wire basicly into a resistive heater for a verry short moment.
Then the circuit breaker cuts the connection to prevent a cable fire due to the current flow being absurdly much above the specification of the electrical system.

Grabbing a high voltage supply line and just smashing in into its counterpart causes havoc because of an entirely different effect.
You know that electricity always takes the path of lowest resistance.

If the supply line touches the other part of the supply line somewhere along its way, the path of lowest resistance is no longer down the line to the next traffo station as that traffo station is bigger load on the supply (aka a bigger resistance) then just two bare metal wires touching.
Thus, the power going to that transformer is suddenly cut.
Now, you still have the same supply voltage, but suddenly, the overall resistance of the entire system is cut significantly.
And we are not talking the AC of one house switching off, we are talking entire parts of a city suddenly no longer drawing power.
We know that I=U/R, and as U is consistent and R drops, I immediately jumps up.
It is like two people pushing against a piece of furniture that is about to fall over and suddenly one of the 2 just lets go and jumps back.
That person will be totally fine, but you suddenly have to endure twice the current flow UGH I ment weight of the furniture pushing and in turn, you get crushed.

Same if a power line touches ground.
Power suddenly no longer runs it's supposed path, overall load drops (a fault to ground is basically a 0 ohm path), current spikes.

If a lightning strikes a power line, the overall energy in the system suddenly spikes dramatically, thus current and voltage spike.

All of these things can mean insanely violent destruction of anything in the path of the current and not somehow protected by being separated by any component taking the brunt of the force (aka surge protector).



Our power grid is designed to adapt to changes in power demand pretty good and pretty fast.

It's actually kind of a fun amazing fact that there will always be the EXACT same amount of energy being put into the grid as is being needed at that verry moment.
It is always perfectly balanced.
How? Mostly huge moving masses in power plants. If demand increases, these flywheels physically slow down, pushing energy into the grid until the control systems can crank up the power out of what ever energy source that power plan uses.
That is why grid frequency always fluctuates ever so slightly.
Another fun fact there: The grid frequency is always 100% in sync with EVERY SINGLE generator connected to the entire grid.
That is why new power plants celebrate grid synchronization as the start of actual power production.




Oh, and, btw, I am studying engineering.

While not studying electrical engineering, I did pass my exam in the electrical engineering class I had to take last summer.

The exam was on the 19th of June last year, I prepared verry little for it and still passed with a 2.0 (1.0 would be the best, going down to 4.0 being the worst passing grade with at least 50% of the maximum achievable score being needed to obtain that), which is 0.8 grades above the average of the exam comparison group I was added to putting me in the top 36% of students in my exam group (13 of 36 exams in that group were a 2.0 or better).
That earned me 5 of my currently 50 ECTS credits towards my bachelor's degree.
Only 130 to go, yay.

So, before claiming profession in something, do a quick reality check of who you are claiming superiority against.



Really, being wrong is totally natural and as an adult one should be abled to stand up to that.

You won't believe how often I insist I am right only to realise that I totally misunderstand what ever the matter was and was the obviously wrong moron who made totally nonsensical arguments.

For real, daily would probably not even be a bad estimate when averaging those occurences over my lifetime.


Post# 1025072 , Reply# 18   2/18/2019 at 23:32 by Launderess (Quiet Please, Thereīs a Lady on Stage)        
ROACHES

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Not so much for the American and or even Western European markets, but for parts of Asia and elsewhere there are specific, and express warnings about keeping roaches out of washing machines in owner's manuals.

When first saw this thought how very odd, then began asking around.....


Post# 1025077 , Reply# 19   2/19/2019 at 00:16 by tolivac (greenville nc)        

Low voltages--these can kill induction motors---the motor draws MORE current than its rated for to turn its load-therefore it can overheat.Helpted my dad investigate a fire related to that matter.and of course motors can overheat if the voltage is too high.At work a 5Hp blower motor ran too hot when connected to a 255V supply when its supposed to work from 230-240V 3ph.The replacement ran too hot,too.The primary taps on the 230V transformers need to be tapped back.also electronic boards failed from the too high voltage as well.

Post# 1025149 , Reply# 20   2/19/2019 at 21:46 by Lorainfurniture (Cleveland )        
The only issue is that Iím right.

energytoday.biz/blog/brownouts-w...


Some appliances and electronic devices may be damaged if polarity is reversed

Some appliances and some electronic equipment may be damaged if left connected to a reversed-polarity electrical circuit.

We disassembled a coffee maker that had burned-up and found that the appliance had been damaged by being left connected to its receptacle with polarity reversed. The presence of live voltage at the "wrong end" of a circuit or circuit board may cause some devices on the board to remain energized even when the device has been "switched off". A result can be overheating or electrical shock hazards.


inspectapedia.com/electric/Elect...

Spend about 10 minutes as I have doing a quick google search and learn something. I have no problem admitting when Iím wrong, you consider the same


German roaches are attracted to warm circuit boards, and they short them out.


Post# 1025908 , Reply# 21   2/28/2019 at 14:30 by potatochips (Nova Scotia)        

I know I am bringing up a slightly old thread but I have to chime in here. 

 

With regards to the polarity discussion, there is a good reason why one blade of a plug is larger than the other and its designed to fit one way. Some stuff can be plugged in regardless of polarity but other cannot. Yadda yadda yadda. Best not to force it if there is a reason why its meant to go one way and one way only. 

 

Brownouts can cause failures of certain electronics. It depends on how sensitive they are. A friend of mine is an avionics mechanic and has told me that certain ground power units hooked up to certain commercial airplanes will not mix as the aircraft rejects the power and trips itself as a form of protection. Some of our equipment in the hospital is highly sensitive and will not accept bad power, and in brownout situations can trip. However, the power situation at the hospital is very regulated to prevent these machines from tripping just willy-nilly and we have a fair amount of equipment to reduce that risk. 

 

Certain high voltage VFDs I have experience with will also trip if they experience a supply undervolt, under current, or under frequency. Motors are especially prone to brown out issues as someone had mentioned, cooling, is not there like it used to be if its not getting the required jam. 

 

And Henerik, I think you have it backwards. If the load demand increases on a power plant, the generators speed (which directly relates to grid frequency) slightly (and I mean slightly, like .1 Hz depending on how good the AVR is) decreases and MW output more or less remains the same or slightly (and I mean slightly) decreases. The AVR sees this undervoltage, the turbine speed sensor picks up the slight speed decrease and together the both of them control the boiler to fire more, thus increasing generator output. 

 

Yes, it is a party when a new plant syncs to the grid for the first time. We had a pizza party at the refinery when we did for the first time. 

 

Full load rejection on a 150MW turbine is kinda scary. A few fellas I worked with at the refinery worked at power plants in Alberta during the LA earthquake of 1994 and they felt it all the way up in Alberta. Tripped two 300MW units. North America is broken up in to a few different reigons for power that are not interconnected. Western US and Canada is one, Eastern Canada and north eastern US is another. Texas has its own... 

 

Oh, btw, I used to work at a power plant, and the refinery I worked at we made our own power with a 62MW junk Siemens turbine. 

 

 


Post# 1025913 , Reply# 22   2/28/2019 at 16:39 by bewitched (Italy)        

we have not such things as polarized sockets or plugs in normal households. the line is single phase 220v 50hz and no one knows what is the polarity unless you measure it with a phase checker. if something goes wrong the life saver switch cuts power instantly. should your hair dryer fall in the bath tub when you are inside nothing happens except quick power cut. the only polarized sockets and plugs are those for 380v 3 phases but few households here have it nowadays.

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Post# 1025999 , Reply# 23   3/1/2019 at 17:49 by chetlaham (United States)        

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I'm with Kb0nes and Combo52- reverse polarity will not harm anything, and 99.88% of the time the appliance can not tell the difference. About the only thing that I know of that can't take reverse polarity are some gas water heaters and furnaces- and its probably from what Combo mentioned.

In fact if you read Whirlpool's dryness sensor patents they specifically talk about designing the control so that it will still function with reverse polarity and without energizing the frame. Truth being gobs and gobs of appliances go into homes with reversed polarity, missing EGCs or both. Knob and tube, joe DIY hack jobs, non grounding outlets... its a given.



And thank you Kb0nes for the van-diagram. Surges aren't as common as people think- especially regarding failed electronics. People are always calling their POCO after the lights dim (from a voltage dip) claiming surge damage to cover a device that had already failed was going to fail anyways.

And FWIW the average home has so many MOVs from each circuit board having one that whole home surge protection is basically all ready in place.


@Combo52: During storms my lights dim all the time from trees falling into lines- you are correct that absolutely no harm is done.



And BTW- you are at orders of magnitude far greater risk (by occurrence)of an open neutral which electricians deal with all the time. Most surge protectors, even the best and glitziest ones will do absolutely nothing other then literally turning into a pile of melted flaming plastic. Yet you don't hear a peep about this from joe public or those making surge protectors.


Post# 1026002 , Reply# 24   3/1/2019 at 18:07 by chetlaham (United States)        

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@bewitched- yup- and if you look at countries like the Philippines they run two hots to every socket and light fixture to get 230 volts as they use a center earthed supply like the US but simply don't have anything 120. Then you have older system in Norway which are 230 volts IT, meaning the supply transformer neutral is not earthed at all.


The only reason the NEC cares about polarity is from Edison base screw sockets- they don't want people being shocked while unscrewing a light bulb should they touch the metal base.


UL testing requirements for small tools and appliances actually subjects them to reverse polarity and open ground- in order to pass they must not shock or dangerously malfunction.


Post# 1026003 , Reply# 25   3/1/2019 at 18:13 by chetlaham (United States)        

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@Potatochips: Doesn't excitation regulate reactive power (MVAR) output while speed is in proportion to real power (MW) output?

Post# 1026008 , Reply# 26   3/1/2019 at 19:56 by potatochips (Nova Scotia)        

@chetlaham

 

The AVR (auto voltage regulator) will pick up in a reduction in voltage output and crank up the DC excitation voltage in the rotor to make up for this slack, adding more excitation volts will only increase real power to a point, but then reactive power production goes up if too much is added. The opposite can be said if there is an over voltage situation. Excitation voltage is also used to control the power factor. The power plant made 13.8kV off the end of all generators we had, and then we stepped it up to 138kV in the switching yard for transmission.

 

No, speed is not in proportion to the generators MW output. The speed is directly in relation to the frequency made. A two pole generator needs 3600rpm to make 60Hz power, 4 pole needs 1800rpm, 6 pole needs 1200.

 

Once the turbine was up to speed, 3600rpm (or 1800rpm for that junk Siemens machine) wed switch the boiler control to Boiler Follow (meaning the steam generator would slave to the turbine), then we used a synchroscope to bring it in phase with the grid. This can be done automatically, but best practice as taught to be by a bunch of old fellas was to sync it manually, nail the frequency, then put the syncroscope in auto, then close the breaker to the grid. The idea is if the auto sync system failed and switched to manual, its already set up in manual.

 

Once the breaker was closed on the turbine and it was on the grid, it was doing 3600rpm with no load, 0MW. On the 150MW turbine the boiler would be about 2% MCR (max continuous rating). We would then release the turbine control to the Electric Control Centre or ECC. At this point the plant was hands off. The turbine followed the grid demand, and the boiler/steam generator followed the turbines load demand. ECC would increase the MW demand at a steady and predictable rate taking care not to over stress or over load any of the equipment. Usually a MW a minute or so.

 

The entire time the turbine was spinning at 3600rpm, never changing speed. The torque demand is where the power is generated from and that was met by firing the boiler more. And since the boiler was in Boiler Follow mode and slaved to the turbine, if the turbine asked for more the boiler gave it. Adding excitation voltage increases the torque load of the flux lines the rotor has to cut through. Interesting enough the poles on a turbine generator are the rotor, and the stator windings are where the power is actually made. This is because the exciter windings are a lot less mass than the generator windings, and its something like the generator would be 4 times the size if that was the case. The logic for the turbine looked at its speed and the voltage output via the AVR for control and adjusted as necessary.

 

If you lost a turbine on a generator trip it was pretty scary. The whole place comes to a grinding halt in a split second. The breaker opens, that sends a trip signal to the turbine throttle, which sends a trip signal to the burners. It all cascades back and if youre lucky enough you wont pop a safety valve and wake the neighbors. The junk Siemens turbine had a dump valve on the inlet header so that any full load rejection shouldnt lift a safety valve. When a steam generator is making 1.5 million pounds of steam an hour and all of the sudden it doesnt have a place to put said steam...

 


Post# 1026010 , Reply# 27   3/1/2019 at 20:15 by chetlaham (United States)        

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I hear you- but add just a hair of speed or at least try to and you pickup more MW, reduce just a bit (or try to) and you output less MW. But I hear you, in the end the rotor has to be in phase and turning without slip no matter what- which I assume thats what you mean?


"The entire time the turbine was spinning at 3600rpm, never changing speed. The torque demand is where the power is generated from and that was met by firing the boiler more. And since the boiler was in Boiler Follow mode and slaved to the turbine, if the turbine asked for more the boiler gave it. Adding excitation voltage increases the torque load of the flux lines the rotor has to cut through. Interesting enough the poles on a turbine generator are the rotor, and the stator windings are where the power is actually made. This is because the exciter windings are a lot less mass than the generator windings, and its something like the generator would be 4 times the size if that was the case. The logic for the turbine looked at its speed and the voltage output via the AVR for control and adjusted as necessary."

Ok- I understand now. I want to say beautifully written- many thanks for the detail. I truly appreciate it.



"If you lost a turbine on a generator trip it was pretty scary. The whole place comes to a grinding halt in a split second. The breaker opens, that sends a trip signal to the turbine throttle, which sends a trip signal to the burners. It all cascades back and if youre lucky enough you wont pop a safety valve and wake the neighbors. The junk Siemens turbine had a dump valve on the inlet header so that any full load rejection shouldnt lift a safety valve. When a steam generator is making 1.5 million pounds of steam an hour and all of the sudden it doesnt have a place to put said steam..."


Question- does the steam dump to the exterior? Like one of those initial steam purges before starting electrical production for the first time?


Post# 1026011 , Reply# 28   3/1/2019 at 20:46 by potatochips (Nova Scotia)        

Yeah the rotor never really changed speed based off MW load. The controls are so finely tuned that any change was smoothed out almost instantaneously. The speed change was only because more torque was added/subtracted to the rotor from a load demand increase/decrease. Any slip on that turbine would mean were making dirty power, which ECC had the ability to disconnect us from the grid if they started to see weird things. Once the generator was tapped out, it couldnt make anymore and it just sat there pounding out all the MW it could maintaining 3600rpm all day. There are ways to cheat the system by bypassing feedwater heaters and stuff to try and get more MW out of a turbine but the plant becomes inefficient then.

 

Oh yes, the steam would vent to the outdoors from either the dump valve or the safety valve. Newer plants may have silencers on their safety valves but ours did not, and the plant could be heard from about 15km away. The noise isnt like a scream you would imagine like what you would hear from an old train. It was more just a wad of noise similar to a fighter jet. The refinery had silencers on the dump and safety valves so it was just a low rumble at best. Lifting a safety valve is a very very very rare occurrence. In one province in Canada, lifting one was a reportable event to the regulator.

 

Some turbines do require an initial purge or venting to atmosphere before steam admission to the blading to ensure high quality dry steam. This is more so low end, low MW dumpy turbines. But most closed loop, regenerative turbines you find in a power plant have lots and lots of drains on the lines so that only screaming hot dry steam is at the turbines inlet valve and is admitted nice and slow, and because the whole thing is under a deep vacuum it just flows through readily requiring no atmospheric dumping. Its a waste of money to vent all that steam, so the drains dump back to the condenser.


Post# 1026012 , Reply# 29   3/1/2019 at 21:00 by chetlaham (United States)        

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How many MW was your plant rated for?

Post# 1026015 , Reply# 30   3/1/2019 at 21:22 by potatochips (Nova Scotia)        

Just under 500MW. Three units. The refinery was plated for 80MW but the imagineers at Siemens dropped the ball on the condenser so in the summer you could only get 62MW, and in the winter if you were lucky about 70MW.

 

Siemens makes crappy steam turbines anyways, and they now service Westinghouse (WH turbines were also 'well made'), AEI, Reyrolle made machines so you can only imagine how well theyre taken care of. The best turbines money can buy are either Toshiba or Hitachi, their service is insane good.


Post# 1026040 , Reply# 31   3/2/2019 at 06:27 by chetlaham (United States)        

chetlaham's profile picture
Sounds like fun!


Thank you for the heads up on Siemens. Was not aware Toshiba and Hitachi were so good- I'll keep these things in mind.





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