Generator Reverse Power Trip on synchronizing
Generator Reverse Power Trip on synchronizing
(OP)
Trying to commission a 11 KV, 2.5 MW steam turbine driven generator. The generator recently rewound and tested OK. Phase sequence also checked ok.
On synchronizing, the generator trips on reverse power every time. The turbine engineer says the turbine, the governor and the steam valve are ok.
I noted that on closing the breaker, the power factor goes haywire and the Woodwards Multifunction Relay reads about 100 amps in all 3 phases but the power is reading (-) 358 KW and the excitation is reduced to zero. (I will post two photos of the control board meters - before and after synch)in the following posts.
The AVR is Basler. I think the AVR is malfunctioning. Any other possible reasons for the RPR to act every time ?
On synchronizing, the generator trips on reverse power every time. The turbine engineer says the turbine, the governor and the steam valve are ok.
I noted that on closing the breaker, the power factor goes haywire and the Woodwards Multifunction Relay reads about 100 amps in all 3 phases but the power is reading (-) 358 KW and the excitation is reduced to zero. (I will post two photos of the control board meters - before and after synch)in the following posts.
The AVR is Basler. I think the AVR is malfunctioning. Any other possible reasons for the RPR to act every time ?
Muthu
www.edison.co.in





RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
Well it went all bonkers when the CB was closed...The excitation went to zero and the governor must have closed the throttle valve too..We cant read anything on the digital gadget there, but check first--
-The governor system is trying to to pick up a small loading immediately when the CB is closed, in other words the synscope must be rotating very slowly clockwise at breaker closure. I assume there is actually a synchroscope somewhere.
-That the incoming and running voltages were properly matched before CB closure.
-That the AVR is set so that a slight positive var flow will result at CB closure. It looks like it was set the other way in that the AVR saw too high a voltage at CB closure and ran the excitation to zero.
We see that the stator current went to a high value, indicating a bad mismatch, and the power went to negative kw.
-see that the AVR cross current compensation is connected properly. It may be reversed, meaning that it will go immediately unstable. Try shorting out that CT temporarily.
The governor system has to have a problem in that it is closing the throttle valve immediately. It can be that a load feedback is reversed. You said Woodward, they have something like that. Often called Load Pulse I think. Try disabling that.
There are two problems at the same time it seems. Possibly integrated into one controller?
Try synchronizing manually. See what happens to the steam valve, it should not go closed immediately.
It can be that PT and CT connections are wrong and that vars and watts are not being measured correctly.
The metering looks correct. Is that on the same PTs and CTs as the control?
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
That still would not explain why the governor is closing the steam valve, it can be that there is a load feedback that is in some way wrong.
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
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If we learn from our mistakes I'm getting a great education!
RE: Generator Reverse Power Trip on synchronizing
At least the metering on the panel was sensibly designed. One glance and the whole picture is evident.
Let us know what you find. There must be some wrong connection from the PTs and CTs to the Woodward so it is not measuring KW actually. Possibly someone damaged something in the electronics using a Megger on the wiring, not uncommon.
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
I haven't found any text books that talk about this, but it's important.
RE: Generator Reverse Power Trip on synchronizing
I see 10.29 kV on the square LCD monitor before closing and 10.84 kV after closing.
Jack up the set voltage. It looks like the grid voltage is above the set voltage. Once the breaker is closed the grid is feeding 18.84 kV to a generator outputting only 10.29 kV. The AVR sees the grid voltage and shuts the excitation down trying to drop the voltage. Then the grid excites the generator as if it were an induction generator. The result is a bad power factor and about 358 kW of losses in the stator caused by the exciting current.
Run the set voltage up to 10.84 kV or more. That should get you close enough to avoid a reverse power trip. If it still trips, be guided by the voltage shown after closing and set the voltage up a little more.
The root of the problem is most likely metering errors. The meter showing the grid voltage does not match the meter showing the gen-set voltage.
The old school fix is to bump up the voltage until you can sync without a reverse power trip and then either adjust the meter calibrations until they match, or get out the magic marker and put a mark and/or instructions on the face of the voltmeter.
The more accepted method may be to pull the PTs and Voltmeters and have the PTs checked and replaced if faulty and have the meters calibrated to the same standard.
The set voltage should be at or above grid voltage when closing the breaker. Yours voltage seems to be about 5% low when closing.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
An expert should have it sorted out within the first hour or less. Unless it is a complete mess of course.
If you send an attachment to us on the forum showing the panel connections in a pdf or CAD format we may be able to pinpoint the fix to the situation.
I assume that would allowed by the client and the forum.
Is this an upgrade to an old plant? Sounds like that. Are there other generators working on the same busbar? Were the existing old PTs and CTs checked out or changed as suggested by others?
Is this a Basler digital AVR? What versions of Woodward equipments are used there?
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
That being said I agree that 5% allowable delta seems too high. I would set it at 3% and see what happens. Athough I haven't yet wrapped my head around why leading reactive power surge would cause a reverse power trip.
RE: Generator Reverse Power Trip on synchronizing
Should be governor issue rather than AVR.
I belive that synchronizing shall issue an increase frequency command right after closing in order to avoid the P<- trip.
Some product have the means available, just need to activate it.
Rgds.
RE: Generator Reverse Power Trip on synchronizing
Reverse power usually indicates a motoring condition, but not always. As I read the meters the AVR is removing the excitation in a futile attempt to drop the grid voltage. Once the AVR shuts down the grid excites the generator as if it were an induction generator. (Probably not all that good for the rotor.) There will be a grid supplied exciting current in the generator and this current will cause I2R losses. These losses are supplied by power flowing from the grid into the machine. Hence a reverse power trip without a motoring condition.
Is the AVR in voltage control mode?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator Reverse Power Trip on synchronizing
If that has happened, on the next start up it will not be possible to get full stator voltage, and the exciter field will be overloaded on a sustained basis.
In this case the diode fail protection will sense the sustained exciter field overcurrent and trip the excitation off after a time delay.
Let us hope that diode fail protection exists and is activated.
The assumption is that this is a brushless exciter...
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
RE: Generator Reverse Power Trip on synchronizing
RE: Generator Reverse Power Trip on synchronizing
However, the reactive current causes I2R losses in the generator. Those losses are real power and that power (-358 kW) will be seen by the reverse power relay.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator Reverse Power Trip on synchronizing
It's not such a big problem on modern low-burden digital relays but it is a documented problem with electro-mechanical relays. The problem exists as a result of phase shifts through the instrument transformers. On a gas turbine the motoring load of the compressor is so large that it would be difficult to set a relay so badly as to not trip the set, but a steam turbine spinning in vacuum has a very small motoring load relative to the size of the set and that can make relay setting tricky and / or cause misoperation. The problem is worse with larger sets because their motoring load is a smaller fraction of the set rating than on a smaller machine. Hydrogen-cooled sets - which tend to be large ones - have lower windage losses than an equivalent air-cooled machine.
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If we learn from our mistakes I'm getting a great education!
RE: Generator Reverse Power Trip on synchronizing
Today, the Basler AVR engineer found out that the PF control of AVR was not activated. New diodes are expected in 2 - 3 days.
I also checked the steam control valve manually from the 0 to 100% opening. The valve stem play was 11/4 inch for the entire range. I was assured the actual valve opening was checked and found ok.
I advised the client to disable the AVR auto mode and synch the machine manually and control the var load manually. Asked the turbine engineer to set the load at about 200 KW and see what happens to the stability of the machine. If it is still hunting, then it must be the governor issue. There is no setting for the governor to lock the load at a particular KW since there is no pressure or flow rate feedback loop.
Will post the AVR photos in the next posts.
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
A couple more bad syncs or losses of excitation, etc. may result in some heavy damage both electrical ond/or mechanical. Is this a geared turbine? Possibly a new gearbox will be needed also, that is not a joke. A certain GT gearbox disintegrated, exploded that is, after one bad sync too many ...
The reverse power relay is not supposed to trip on overload, that implies positive power output to the busbar.
The PF control on the AVR is not relevant, or should not be. Normally that is a slow-acting correction on the voltage setpoint. Disable that for now.
Yes, see if you can run it manual excitation. But make sure the overvoltage protection is working first as well as overcurrent protection. Set that down to a conservative level in case it all goes bonkers again. Likely...
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
Put the governor in droop mode. The setpoint will then control the load level.
Try really hard to get the generator voltage up to the grid voltage before the next attempt. Be aware that the calibration of at least one of your voltmeters may be off.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
It looks like the whole scheme has to be recommissioned from the ground up.
Obviously each "Expert" will claim his part is perfect.
Is there really someone there from Basler?
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
This is only a guess on my part having looked at the Basler website.
Can anyone clarify this? Possibly that is why there are problems with the AVR configuration.
Yes in fact there is cross-current compensation via a CT in the center phase, as well as PF, VAR, and manual control.
The manuals can be downloaded from the Basler website in pdf. Well worth a look.
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
The field output on these has relatively large steps, I used to get a lot of trouble calls because at low loads the power factor would appear to have large swings. Things would usually be fine after load gets up abit.
Have you tried using the AVR in Manual Mode? This is a great troubleshooting tool. From Bestcoms, on the configuration page, select Manual On, then use the settings page to raise and lower field output.
Who setup the initial PID settings? I have never had much luck with the calculator, and my experience with these is on larger CAT units and a couple of small PERP hydro units.
Before trying to parallel, use the Step Resp tab to evaluate the units response, a bad set of PID settings can be a contributor to your problems.
I usually set them up no load, test the step response at 5% up and down, then try it. If I'm having problems like you seem to be I'll parallel it in manual, and use the metering page to look at the parameters, this way you can tell if the readings are correct.
The Basler folks here in USA are usually pretty helpful, not sure about support where you're at.
Download and use the software, it's way better than setting and and reading from front, and you can save setting files and see the metering.
Hope that helps.
RE: Generator Reverse Power Trip on synchronizing
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
I do a fair number of conversions from the older DECS to DECS200's every year, main reason is that end user wants better control or more features. The DECS 200 tracks very well and I have some island mode plants where the VAR share with minimum droop settings are excellent. I also did a diesel electric drive research vessel about 2 years ago, the older AVR's had a hard time with voltage stability in rough seas. The DECS200's did very well after carefull setup and adjustments.
One thing that will kill a DECS 15 almost everytime is an open in the field circuit. They will either fail completely or act goofy. I had sites where the protective relays operated a field breaker from the previous AVR install, first time the protection operated, the AVR was done. Make sure the field output goes direct to the field and there are no opens or bad connections. If you need to kill excitation, open the power leads to the power supply, not to the DECS from the power supply or in the field circuit.
A note of caution, not sure the technical savvy of your Basler rep, the DECS 200 is a VERY nice regulator, but has more menus and things to go thru, if your guy is having trouble with the DECS 15 the DECS 200 will likely be over his head. A DECS 100 will likely not work, they are a maximum 65 VDC regulator, suited for smaller gensets. The Marathon DVR is a branded Basler DECS100. Nice unit but likely not usable for yours unless you have a lower power excitaion system.
Hope that helps, good luck.
Mike L.
RE: Generator Reverse Power Trip on synchronizing
Now we have an hands-on expert on Basler AVRs on the forum. You have summed it up nicely. Does anyone on the jobsite know all this?
Now I have looked up on the Woodward site the info as a pdf download on the MFR2 device on the panel that someone has a finger on there,in the photo.
It is a regulator, PF controller, synchronizer, certain relay protections, displays, and more...all depending on how it is programmed. It may be working against the Basler or with it...
Have a look at the Woodward download site. One has to register first. Well worth the time.
With all this fancy kit just how did they manage to do a bad sync maybe more than once...perhaps wrong connections, programming, or someone pushed a relay in by hand...not unknown in this business.
Just too many specialists on the site, and no-one overseeing the total job, possibly.
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
- governor problem, never could be avr problem, cause the reverse power is active reverse power, and it´s not dependent on AVR.
- error on current transformers connection to the reverse power reley, i have see this problem a lot ot times...
RE: Generator Reverse Power Trip on synchronizing
for me, before synchro is good to open the star point on generator, and switch the circuit breaker (after megger) and cheek sequence of phases on all the voltage transformers, then you open CB and start unit and cheek the sequence again and must be the same, and so, then you take out the relay for closing CB and connect a analogic multimeter on volts and cheek the moment you give the commant for closing, in this moment, all the thres multimeters must be on 0, this means you could syncronize.
After syncronize, if your AVR is not on power factor control, in the beginning you are not gonna trip but then reactive will swing and trips.... but never, a reverse power trip.
i hope i could help and sorry for my english.
RE: Generator Reverse Power Trip on synchronizing
I suspect the generator lost excitation and was running as induction generator. Does this Basler AVR DECS 15 have provision for sensing loss of excitation ? If yes, how does it sense it ?
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
What kind of plant is it? Are there other generators in service there also? We could help out if some dwgs and other factual information were made available, at least to see if the concept, choice of equipment, and connections appear to be serviceable.
There are a lot of experts available here on this forum. There do not seem to be any on that site.
How do they manage a bad sync with the Woodward MFR2 which is also a synchronizer? Programming wrong...? Were the syn PT conns properly checked to see that the synchroscope reads 12 oclock with the GCB closed with the same voltage on each side? That is the line side open elsewhere and using only the generator voltage? You said phase rotation was correct, that had to be or else it could never have been paralleled at all...
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
Now the client faces the question whether to dump the generator or rewind the rotor.
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
If the AVR fails and then results in a failed rotor, I think the protection scheme is not adequate, at least in my opinion. For a loss of excitation to cause a rotor failure means that after the AVR failed the breaker remained closed and the unit now absorbed VARs rather than generates them, do it long enough and the rotor can fail.
It can also be that the rotor failed, and the diodes and AVR are subsequent damage. Do you know at this time failure mode of the rotor?
DECS 15 has a UEL function, depending on how it's integrated into the overall control and protection system will dictate how well it works for acting as a 40 device.
It's not that I'm a huge fan of the DECS 15, and a DECS 200 will give your client much more capability, it's just that I've replaced a fair number of these regulators when they were blamed as being the problem, only to get the system back on line and find the real root cause.
A few years back CAT went thru a huge number of diode failures, and all kinds of things got blamed. In the course of investigating a number of failures, I found that at least on a lot of units I was dealing with, that a 40Q loss of field protection only worked as expected on a total loss of field. We ate a fair number of rotors, and a few stators due to partial field failures and coupled with poor capablity of the installed PM's, we had AVR's sitting at an available full field point, a large leading power factor, still on-line, only to be taken off line by thermal protections or an attentive operator. I had a hard time putting a unit into srvice after that without reverse VAR protection as well, usually at a level equal to about .8 leading power factor. It wasn't the fix for the primary root causes of the problems, but did limit the number of failures caused by subsequent damage.
I like your idea, do it right completeky.
RE: Generator Reverse Power Trip on synchronizing
RE: Generator Reverse Power Trip on synchronizing
No, i don´t think so, i´ll share with you a document about a bad synchonization... and the process, my experience tells me that in a loss of excitation, you have to be some time to kill the rotor, cause the problem is in one way, you can have a out of step, and finally high current incoming or you keep running like a asynchronous generator, and your damp winding will be burned, cause their are no dimensioned for such flow of current, they act like a squirrel case, and for this you need time, and as you said you are out cause of reverse power, but take care maybe you are using relay from GE, and they have one relay,now i don´t remember the name, that measures on the same relay inverse power and loss of excitation, but in any way,
I think about a bad syncronization, but it you do it, and diodes are broken you need to feel a high current coming into windings, the same if you have a out of step,
And about loss of excitation, decs 15 have a UEL (under excitation limit) that senses the reactive component on the current sensed and depending on the adjunted amount of that reactive it give an alarm if its properly configurated, and conected to alarm, cat, talk about decs200, yes this is better cause you can integrate the curves of the generator on the subexcitation side, but sometimes is not so needed, and i use to say that avr is no a protection relay, it´s just an avr, and for some applications decs15 can work good enough, the question is that basler stopped manufacturing such regulator for that is difficult for spare avr.
i hope this could be helpful, and you can cheek one report i do on a bad synchronization.
RE: Generator Reverse Power Trip on synchronizing
Maybe the generator come with a problem from the repair shop? maybe on the rotor?
About the diodes, if you rewound generator, maybe you have dameges diodes? open diodes, or just damaged, that is enough for getting voltage, but not enough for manage excitation enough for load....and also, the rotor was damaged when you have to rewound.
Could we think about this???
RE: Generator Reverse Power Trip on synchronizing
Whoever set up the generator protections on that project is responsible for the resulting damage. We have still no information on the protections that were provided, and if they were actually tested. Secondary testing only, is not sufficient. Primary testing on open circuit and short circuit is essential using the generator itself as the source. This is absolutely standard test procedure on power station units. I have done this together with the clients on many sites.
In addition, protocols of each test result have to be taken
and signed. Only then can the unit go in service. This is in the interest of all parties on the project.
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
Only when they tried to parallel to the grid, they had issues of first reverse power trip, then overcurrent trip (when they increased the timing of RPR) etc. and in all cases the PF was going haywire along with negative watts (whatever that is). And after their last paralleling attempt (seventh one), they blew the diodes and the rotor along with it. As seen from the one of the photos I posted above, the exciter current and voltage went to zero on synchronizing before the machine tripped on overcurrent.
So I base my conclusion on these facts. Though I admit AVR is not a protective relay, in a brushless system it must provide some sort of protection for loss of excitation.
Anyway, I recommended to the client that the whole system including the turbine control needs an independent review by a system expert.
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
catserveng - "it's just that I've replaced a fair number of these regulators when they were blamed as being the problem, only to get the system back on line and find the real root cause." - What was the real root cause ?
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
So it could be that the phase rotation was actually wrong.
In this case on paralleling there will be severe damage immediately. If in fact that was the case they are fortunate that nobody was hurt. But the Instantaneous OC on the stator should have tripped the CB in milliseconds limiting the damage. But I rather doubt that incorrect phase rotation was the case, something would have been wrecked beyond repair.
It appears that the AVR did malfunction, see the above posts regarding cross-current compensation for example.
Was the synchronizing properly tested? A 180 or 120 degree out of phase closing will result in severe damage, the diodes would at the very least not survive.
Let us hope that after the rebuild, better qualified people are available.
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
And then the relay test engineer double checked it with in his own method by using both the bus PT and the generator PT.
Synchronization was done properly, first automatically and then manually.
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
What did the turbine governor do at this time? Did it open up the inlet valve and attempt to pick up load? Perhaps it closed the inlet valve seeing a slight overspeed due the positive slip.
The root cause is probably the AVR cross-current compensation being backwards or disabled, and the damage is due to too high settings or non-operation of the stator overcurrent protection. It appears that no primary testing of the protections was ever done first. On the next attempts, reduce the OC protection setting to less than 0.2 PU stator current and a time lag of a few seconds only for the first sync. Can be raised later when the unit goes into normal service. Have the client see to it that the tripping circuits actually operate.
regards, rasevskii
RE: Generator Reverse Power Trip on synchronizing
I few of the things I've seen in situations similar to yours, a running unit taken down for repair then put back into service,
Faulty diodes, tested ok with DMM but under load failed, have seen this in CAT, KATO, EM and AVK tailends. I'm pretty hard about changing diodes and surge suppressors on repaired tail ends these days, the couple hundred bucks (US) for the parts sure makes it good insurance in my mind. But boy do a LOT of people not do it.
Over the years I have found three instances of connection problems with rotor pole jumpers after repair, one was a bad solder joint, one a bad wire crimp, and a loose bolted connection. All were very hard to find, resulted in AVR and diode failures until they were found. One of these was found doing a pole drop test (initial pole drop test performed at install was good), the other two putting the AVR in manual and watching the field, then doing a physical inspection when data indicated a problem with the rotor.
Numerous times have had the droop CT hooked up backwards, both primary and secondary on reinstall of tail end. Even in a couple cases it was not reconnected at all.
Numerous times bad field and PM connections, usually due to cage type terminal blocks and them being damaged by technicians with improper tools and/or procedures.
Once a small adjustable wrench left in the excitor stator housing (caused intermittant problems for two months), finally made a big enough problem to make a real mess and cause us to look under the cover again.
A few occurances of problems with the pole piece windings, both on new and repaired machines, usually due to nicking wires during wrapping, and problems not showing up for a while. There was a batch of KATO tailends sold to CAT for a project that all generators either failed or showed high vibration after 2-6 months, they said root cause was something to do with a tensioner on a wrapping machine nicking the wire. We swapped all the tail ends and no more problems that I am aware of at that site.
And in a few cases, just a bad repair process by the repair shop, usually everything looked ok initially, but problems cropped up soon after being in service, sometimes right at first close.
I miss field voltmeters in panels, on older sets they were common, and when the unit started and came up to speed you could see the relationship between the field output and the generator voltage. It was also nice to see what the field did right after sync, especially since DMM's and digital controls don't update very fast, and being able to see an analog meter gave you a great idea of what was happening. When I do startups or troubleshooting now I drag out the Simpson 260, not very high tech, but is helpful to me. I have talked a few customers into going back to field meters in their switchgear, mostly small island utilities where lightening strikes and tree branches are common, using the data from the field meter helps indicate if a tail end problem is brewing by a change in field output for a given load.
I can only think of once, in what I felt was a properly protected system, that the AVR was the root cause, it was an early CAT DVR and it went no field to full field after getting to about 1/2 load, it did it so fast that all the operator saw was a jiggle in the amp meter. But the unit had multiple diode failures, then a rotor failure, then I got called in to look at it, when we got it back on line with a repaired rotor and new diodes it was fine, came up on load, operator noted that the "jiggle" was back, had a meter hooked up to the field and took a look, saw the on-off. We replaced the AVR, jiggle went away, and I never went back. It was happening so fast that the 40 protection didn't catch it, the overall system appeared to buffer the transient so it was hard to notice. Even had the tech who had made the previous repairs with me, he said he had looked at the field, he had an older DMM, so we compared my analog meter to his digital, found we saw the analog meter deflect and the DMM only showed a minor change.
Well, hope it helps, and good luck. Remember if it was easy someone would have already fixed it!
Mike L.
RE: Generator Reverse Power Trip on synchronizing
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Generator Reverse Power Trip on synchronizing
Attached is the photo of the generator rotor. It's a 4 pole, cylindrical rotor with many turns of round copper enameled wire. No direct access to any of the pole coil connections. Not a great product, imo.
Muthu
www.edison.co.in
RE: Generator Reverse Power Trip on synchronizing
Loss of excitation problem, i see and the effect in a Stamford generator 2 MW, maybe 6 years ago, was that rotor was ok, but damp windings are destroyed, this is cause the generator was working like an asynchronous one, but for that your need a long time, and about diodes blowing up in syncronism, maybe they are defective, or maybe they blow up on overcurrent, on that overcurrent you get a high voltage on the rotor, and then when diode is broken high current...
And yes, you need to see with a oscilloscope or something like this the current and voltage on the field, cause dec15 when it´s off, you will see zero current and voltage...
I was near some units with no excitation, but syncroniced to the net and nothing occurs, as you are low power, you get a very bad power factor and keep working..
for three or five minutes.
and about my report, yes, they synchronize, without checking the real phase rotation on generator