API 616 overspeed trip setpoint specification
API 616 overspeed trip setpoint specification
(OP)
API 616 5.4.4.6 states: An overspeed trip protection shall operate at 105% of maximum continuous speed. Multiple shaft turbines shall have individual overspeed trip protection for each shaft.
API 616 3.22: maximum continuous speed: The speed (revolutions
per minute) at least equal to 105% of the highest speed required of any of the operating conditions.
API 616 3.38:rated speed: The speed (revolutions per minute) of
the gas turbine output shaft at which site rated power is developed.
For a turbine with a rated speed of 10300 rpm, is it okay to have the overspeed trip at 11330 rpm (110% of rated speed)?
API 616 3.22: maximum continuous speed: The speed (revolutions
per minute) at least equal to 105% of the highest speed required of any of the operating conditions.
API 616 3.38:rated speed: The speed (revolutions per minute) of
the gas turbine output shaft at which site rated power is developed.
For a turbine with a rated speed of 10300 rpm, is it okay to have the overspeed trip at 11330 rpm (110% of rated speed)?





RE: API 616 overspeed trip setpoint specification
Best of luck!
RE: API 616 overspeed trip setpoint specification
RE: API 616 overspeed trip setpoint specification
Also, classification societies (Lloyd's, ABS, Bureau Veritas, etc) and insurance companies have a lot of experience on this matter.
The over speed protection sttings for mechanical drives (e.g. compressors) is typically different than for power generation.
In power generation i've always seen the electrical overspeed protection setting at 110% (10% above rated speed) and the mechanical over speed bolt setting at 112.5%
Since the early 1990's the classification societies, insurance companies and construction codes have accepted the elimination of the mechanical overspeed bolt replaced with a second, independent, set of speed pick-ups for overspeed protection.
saludos.
a.
RE: API 616 overspeed trip setpoint specification
The number 110% seems to be very frequently evoked as overspeed shutdown setpoint!
I have a litle bit of confusion between the different terms used in the standard; what is the relation between the MCOS (maximum continuous speed) and the Rated Speed?
Stgrme, in view of API 614 section 1.1 (The vendor may offer alternative designs), how do you evaluate the compliance to the API614 standard?
RE: API 616 overspeed trip setpoint specification
RE: API 616 overspeed trip setpoint specification
Generally, the gas turbine will be designed for a particular maximum speed. This maximum speed, determined by the gas turbine vendor, is selected based on the speed attained on a loss of full load event (perhaps, with a small margin added). The gas turbine vendor chooses an overspeed trip setting to avoid reaching this maximum speed. Setting the overspeed trip too low may result in spurious trips.
As abeltio noted, an overspeed trip setting of 110% of rated speed is quite common for large indutrial gas turbines in power generation service.
For vendor's alternative designs, you must evaluate each deviation from the API 616 standard. If you are not confident in making those judgments, hire a qualified consultant.
Best of luck!
RE: API 616 overspeed trip setpoint specification
Maximum Cont Operating speed (MCOS)= 105% of normal speed, This is the speed that would be required by any of the specified operating conditions.
Trip speed = 110% of of MCOS for steam, 105% MCOS for gas. in relation to normal it is 115.5% (of 100% normal)=105*1.1 for steam and 110.3% or normal = 105x1.05 for gas
The whole idea behind API machines is the ability to meet the process needs at all off design points,
RE: API 616 overspeed trip setpoint specification