Hello,

one of our new GT unit Mark VI controller I have alarm (HP overspeed I/O configuration doesn't match).

I checked the software configuration of the speed pickup and I found that the setting is:
OS_Setpoint =5457 rpm
zero_speed = 15 rpm

I changed the zero speed setpoint to 0.0 rpm so the alarm is gone. but as a result of that, in the start check screen I have not ready to start because of {HP speed not detected since two minutes}.

so is the setpoint of zero speed is correct or it should be more than 0.0 rpm?

thanks.

 

Ayman,

Passive speed pick-ups and passive speed pick-up inputs are not very good at determining zero speed. In GE-design heavy duty gas turbines just as "synchronous speed" does not mean <b>SYNCHRONOUS SPEED</b>, zero speed does not mean <b>ZERO SPEED</b>. Change the overspeed zero speed detection threshhold value back to the original and the second alarm you mentioned will go away.

What happened to cause the original mismatch alarm? Has someone been downloading to processor(s)? Has a card been changed? If so, which card?

I believe that when the Mark VI complains there is an HP overspeed mismatch, it means one of a couple of things. Either the configuration in one of the three VPROs does not match the other two (has someone changed a VPRO recently, or downloaded to a VPRO as part of a download to a single processor), or the signal scaling of the HP overspeed signals does not match the signal scaling of the primary overspeed signals (usually connected to the TTUR/VTUR combination). The Speedtronic, being a configurable controller, has to be told what the 100% speed frequency is--for both the primary speed detection (<R>, <S>, & <T>) and for the overspeed detection (<X>, <Y>, & <Z>).

I want to add one last thing. It's usually never a good idea to change a parameter in a unit that has been running without problems without first understanding if the value is correct or incorrect. Even if it seems the value might not be correct because of the name of the value. You're not the first person to do this, and you certainly won't be the last.

I would like to understand what caused the HP overspeed mismatch alarm. Were builds and downloads being done to the panel or were cards being changed? As an added instructional benefit, contrary to popular mythical belief and lore the answer to many "problems" is <b>NOT</b> to do a build and download. The Mark VI uses a dynamic addressing scheme, meaning that from one build to the next the physical memory location of a parameter value can change--and when that happens, it can wreak havoc with Mark VI operation and CIMPLICITY displays. Resist the temptation to do builds and downloads on the belief "it can't hurt anything--and it just might help!" because it <b>CAN</b> cause unintended problems that can be very difficult to recover from.

VERY difficult.

And, if you do perform a build of the .m6b file and download, make sure to download to all three processors. Building and downloading to one or two processor(s) can cause even more problems--all in an ill-fated attempt to solve other problem(s).

 

CSA,

The unit is new and it is under commissioning. we make download of m6b file to all three processors and the problem didn't solved. the alarm is still there until I changed the zero speed set to 0.0 rpm and the alarm is gone but the second alarm appear.

I didn't change any card but i have one card core <s> VAIC is offline so I have Diagnostic alarm in VCMI core <S> but the two other cores <R>,<T> is okay .

I tried to set it (zero speed) to 5.0 rpm but the problem is same.

Thank you ..