off-nominal frequency tolerance of gas turbines

J

Thread Starter

John Dillon

When bus frequency is abnormal for a sustained time, gas turbines can be damaged from blade resonances and other factors. Depending on the particular turbine and the extent of the deviation, there may be
* no limits specified
* additional maintenance required
* machine trip required

The applicable limits are given by the manufacturer. For instance, i believe that a Siemens V94 typically must be tripped after 20 seconds outside 94%-103% speed, and instantly outside 95%-104%.

GER3620 says for heavy-duty turbines, the design speed range is 95% to 105%. Operation below 95% for more than 20 seconds imposes a maintenance factor, as does operation between 100% and 105%.
Overspeed trips are at 110% and 112.5%.

I'm wondering whether anyone happens to know:
* whether there are any additional limits for a Frame 5 machine (ie for operation below 95%, or between 105% and 110% speed)
* what limits apply for a LM6000

Obviously we will get data from GE but i was looking for a quick indication in the meantime.
 
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