Dear Sir

In Frame 5 m/c Mark6e The actual speed of m/c is 100.1% but speed reference goes on increasing with speed at FSNL it is 100.3%, at 6MW reference speed is 101.3% and at 17 MW it is 103.5% why it is so? In Isochronous mode of speed contol.

Pls enlighten me
Thanks & Regards

 

Dear Sir,

Diagnostic Alarms indicate problems with the Mark VIe turbine control system hardware and/or software. In Vol. II of the Mark VIe System Guide, GEH-6721, you will find explanations of the Diagnostic Alarms. For example, if the PDIO is annunciating Diagnostic Alarm Number 96 (just an example), go to the section of GEH-6721, Vol. II, for the PDIO I/O Pack and go the the Diagnostic Alarm section and find 96 and it will give a description of the alarm condition and a description of what to check or try to resolve the Alarm.

While the unit may continue to run, Diagnostic Alarms can be precursors to turbine trips because of failed or failing inputs or outputs. Just because the unit doesn't trip or shutdown DOES NOT mean the condition being alarmed is not serious and could eventually result in a trip or worse. <b>ALL</b> alarms should be investigated and resolved as quickly as possible--both Process Alarms and Diagnostic Alarms. Failure to resolve alarms can result in loss of production, reduced reliability and even machine damage.

An operator's prime responsibility is to understand and take appropriate action for any alarm which is annunciated. If that means notifying a technician or a mechanic to troubleshoot and resolve the alarm, then so be it. All active and unresolved alarms (Process and Diagnostic) should be understood and logged in writing for subsequent shift operators--and Operations Managers should review all active and unresolved alarms every day, notifying appropriate personnel to work to resolve the condition(s) as quickly as possible. If the alarm condition is deemed erroneous it should be resolved with the help of the control system supplier or packager.

Hope this helps!

 

Dear Sir,

With all due respect I would like to say that this was the answer of my previous equerry of diagnostic alarms.

The speed reference reply is still pending.

Warm regards.

 

Transient Response!

 

Dear Sir,

If the unit is operating in Isochronous speed control, then what's likely happening is that after synchronization the Mark VIe is making Droop speed control track load changes, so that should the unit be synchronized while running with a large or infinite grid the unit will switch to Droop speed control without a load swing.

Actual speed should be relatively stable under Isochronous speed control, unless the load changes rapidly. There is a Droop speed control reference (TNR), which is what is usually shown on HIM displays, and an Isochronous speed reference (TNRI). If the unit is operating in Isochronous speed control, the Isochronous speed reference should NOT be changing, while the Droop speed control reference may be changing for the reason described above.

(Actual speed should be relatively stable if operating in Droop speed control, too. Only the Droop speed control reference changes--which changes the error between the Droop speed reference and the actual speed, which changes the amount of fuel flowing into the turbine combustion system which changes the power output of the turbine and , ultimately, the generator. But the actual speed should be relatively stable--under either Isochronous or Droop speed control.)

Hope this helps!