GE EX2100e 35Amp AVR system

We have a GE EX2100e 35Amp AVR system on a LM5000 which appears to be spuriously tripping the generator.

We would love to exchange ideas/learn form your previous experiences/and share data with an AVR keen team/person with whom we could bounce our troubleshooting and fault finding with.
Good day DNA,

I Would be glad to try to support you, so we can learn and share experience with whom may be interested on the forum .

What kind of issues are you facing ?

Looking forward to hear from you soon,

Hi James,
Below is an overview from our lead engineer and where they currently are at. We have 2 Units referred to in details below. Unit 02 has the issues. Photos etc are not included but I could send them through to help clarify if needed. Essentially the unit has been tripping after being online for less than 24 hours for no apparent reason. We have not restarted now due to issues that have been noted where we are not tripping breaker before excitation collapses which is another issue that could be stressing the Unit. I did read in another post from CSA, where this had happened at another location also.

Yesterday after the trip at [20191116 - 3:01am], we completed another inspection of the Generator Excitation circuit by meggering the Exciter coil, the rotor coil, and testing the diodes and fuses individually. Results were normal and are included with some photos at the bottom of this email.

After the tests, we ran Unit 02 AVR with M2 leg of the AVR isolated – yellow highlighted out of action, see image below. Unfortunately, the unit tripped again at [2019-1116 - 8:37pm].

Also, we installed a current measuring clamp on the outgoing leg of K41 with a MAX setting recording to confirm if there is indeed fault current out of the AVR panel onto the field. The current clamp this morning read 3Amps MAX, and which aligns with the maximum current corresponding to the AVR Excitation current, so this is a good indication there is no real fault current into the exciter coil field.

Unfortunately, this indicates that there a separate common element to the AVRs playing a part here.

Yesterday, we had a discussion with a third party, a very informative session where they shared with us some of their experiences years back at other power stations and we talked about the troubleshooting we have carried out and the steps we have taken.

In past, they faced a similar scenario to the one we face here, and in that case it was found that external interferences affected the AVR control equipment caused the AVR issues experienced.

We are not saying this is the case here, but it is worth considering external influences on the electronics… of these I recall at another site a few years back, that the Displays would automatically change input/turn ON/OFF when radio operations occurred at the site.

So… how can this be happening, how can we rule it out. Possibly causes is harmonics, electronic noise from commuted power supplies, etc.

On the below trends, events, you can see that at the time of the trip, we have a AC Battery charger fail trigger/clear alarms and it coincides with each of the last 3 Trips we have had.

Do they occur before/after the trip? It is hard to say, these points are fed from a MODBUS device so the time stamping error does not allow us to confirm this.

We have looked on the charger logs, and they are also off by a few seconds each, so is difficult to confirm based on this.

The 125VDC Battery Charger supplies two Phoenix AC/DC supplies which feed all control equipment in the AVR Panel through two 28VDC buses. To rule out these and the incoming 125VDC supply being an issue, we have changed the 125/28VDC Phoenix Power Supplies and change to a temporary 240AC supply separate from that of the battery charger. Also, we have turned off the Power Supply from the DC link to the PCM modules, and in this way Isolating any possible interference to the panel from the 125VDC Battery Charger/UPS Panel in the PCMLV2 room.

We have also taken a look at the Unit 01 Diodes, however will not swap them at this stage. Visually everything looks the same.

Appreciate there has been discussions about swapping parts between the two units, but I feel we still have options to exhaust in the CLG2 AVR panel before we proceed this way.

Thanks for sharing with us these informations .

As you stated the "unit tripping after 24h running" , You should get the record trip log events from GPP even from Ex2100e or your Digital Relay protection??
When the unit has been commissionned ?

Did you get faced to this issue just now?

I could not state at this moment if faults occured by exteriors elements at this time.

We should be able to draw what happened before, during and after the event !

These kind of equipments need to get troublesshooting by reading trends /trips /events Manuals ,follow some procedures .

If you able to share documents here is my email:
[email protected]

Looking forward to hear back from you soon,
Engineering team have gone quiet, unit still offline. Will update on progress when available.
Hello DNA,

I would like to add a comment on your issue and some questions are following:

What is actually happening ??
I mean you wrote 35 amp AVR on the title of the thread ?

Is it related to rated field current?
As on you pdf file you measuring I field i guess around 3 amp ?? can you developp??

Looking to battery charger logs is a thing but if you are not able to get alarms lists trends or events log from EX2100e OR IED relay protection ( G60, SR 745 or other OEM ..) you will be underinformed of whta is happening .

Till now I dont have a picture of what happening since datas are needed to get clear view of the trip Causes and effects .

There some time some snubber circuit ( for de excitation ) that can be faulty and make field break tripping .

Also there functions called field flashing / boosting , try to test these functions see if operates correctly.

Did you get any alarms or trip recorded in EX2100e you should be able to check that .

I dont have the single line /protection diagram so i cannot state about how Excitation transformer is located and how Excitation systems and AVR are operating .

To conclude , Some tests are necessary for troubleshooting your Ex2100e issue, IF that is the faulty equipment.

Hope this ca n help ,