During start up we get up to 95% speed with no unusual alamrs and the thing just sits there switching from acceleration to Droop! The speed level will not switch to 14HS from 14HA! Any Ideas?
What have you done to try to troubleshoot the problem? You really haven't given us much to go on.
What Frame size machine?
What fuel is being burned?
What Diagnostic Alarms are present?
What Process Alarms are present?
SIMPLEX or TMR?
Has anyone been doing any EEPROM Downloads or changing any Control Constants or rebooting any processors? (Are you sure about your response to this?)
Conventional combustor or DLN? DLN I or 2.0 or 2.6?
Have you tried to stroke the fuel control valves to see that they are working properly?
Have you changed fuel supplies or suppliers?
If this is a dual-fuel machine, does it happen on both fuels or just one?
Did this just start happening during normal operations, or after a maintenance outage or a forced outage or ?
If gas fuel is being used, what is the P2 pressure (usually signal name FPG2) and what is the P2 pressure reference (usually signal name FPRG)? What is the SRV position (usually signal name FSGR)? I've seen this problem on gas fuel when the y-strainer upstream of the gas valves is plugged and there isn't sufficient gas fuel supply pressure. Also, some sites have coalescing filters which can be plugged. One site did not have the manual isolation valve downstream of the y-strainer fully open.
There have been a couple of cases where high-pressure hydraulic oil leaking past the o-rings in the SRV or GCV actuators would accumulate on the other side of the actuator piston and prevent the actuator from fully opening. This was usually solved by removing a plug (which was inadvertently installed or left there by the manufacturer) to allow leakage to drain away. And, a couple of times the actuator had to be replaced.
If it's happening on liquid fuel, what is the liquid fuel flow-rate reference (usually FQR or FQROUT) and what is the flow-rate feedback from the flow divider (sometimes it's FQL, and sometimes it's FQLM1)? Same thing has been known to happen on liquid fuel: plugged liquid fuel filters, plugged Liquid Fuel Forwarding Pump suction strainer.
If you're not experiencing any "unusual alarms", then it's probably a fuel supply problem of one sort or another. Either there's not enough fuel or fuel pressure or there's some problem with the fuel control valve or actuator.
Or, someone's been mucking with Control Constants or performed some "valve calibrations" that didn't result in proper calibration results.
Somebody's going to write in and say, "Change the servo" or, "Recalibrate the LVDT," but unless there are Diagnostic Alarms or some other indication that would point to a servo problem or an LVDT feedback problems, that's probably unnecessary. (Servo valves are unnecessarily blamed for a lot of other problems; especially poor L.O. monitoring and maintenance practices.)
But, again, you really haven't provided us with any information about the unit, the conditions prior to the problem, what you've done to try to understand or troubleshoot the problem. So, there's not much more which can be said.
Is the aux lube oil pump and/or the aux hydraulic pump still running?
On occassion we have had similar start up events
(unit at 95% speed, screen says "accellerating", yet unit appears in suspended animation, hanging in there... but going no further)... no alarms.
Noticed the aux hydraulic pump was still running
(at 95% speed main hydraulic pump pressure should be sufficient to drop out (turn off) the aux hyd pump.) Hydr. pressure at panelboard gauge looked reasonable, we momentarily turned aux pump "off", then back to auto. Unit then reached FSNL and went into voltage matching, syncronizing and came on line OK.
Another possibility: is the lube oil heater running? During cold weather startup when the units were first put in 17 years ago, we had this
"hanging" at 95% thing occur; If our lube oil heaters are on, aux lube oil pump runs. If the heaters turn on during the start-up sequence, the aux lube oil pump will not drop out... if the aux lube oil pump does not drop out, the end of the startup seqence does not occur... thus the unit "hangs" at 95% TNH. (I can go into this further if neccessary.)
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