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We have a Mark VI controlled Hitachi H-25 gas turbine unit (30 MW) at our combined cycle power plant. Today, after compressor offline washing or "cold washing" as it's referred to at the plant, had been completed, the IGV failed (stuck at 40 DGA) to reach its minimum operating angle of 26.9 DGA. The Operator was able to force the IGV to its minimum position with the hydraulic oil pump on manual.
The Operator tells me that the hydraulic oil pump apparently stopped right before the IGV had reached its minimum operating angle with the hydraulic oil pump on manual.
The fact that I was not physically present when this occurred, I could not verify a lot of the things Operations are saying. The turbine is now in operation and the IGV + hydraulic oil pump seem to be working fine. The IGV went from 26.9 DGA to 54 DGA and beyond during start-up and the hydraulic oil pump pressure is also within acceptable limits.
I have looked at the Hydraulic Oil Pump Control logic on Mark VI Control System Toolbox to try and come to a solution.
I looked at L4HQRUNZ (Main Hydraulic Oil Pump Control Enable), which I have identified as the main Hydraulic Oil Pump Control command. This signal needs to be high for the pump to work. According to the logic, the only way the pump can stop prematurely is if the lube oil pressure drops. Could you kindly verify if my assessment so far is valid? Is there possibly something else wrong here?
Thanks for all the help in advance.
The Operator tells me that the hydraulic oil pump apparently stopped right before the IGV had reached its minimum operating angle with the hydraulic oil pump on manual.
The fact that I was not physically present when this occurred, I could not verify a lot of the things Operations are saying. The turbine is now in operation and the IGV + hydraulic oil pump seem to be working fine. The IGV went from 26.9 DGA to 54 DGA and beyond during start-up and the hydraulic oil pump pressure is also within acceptable limits.
I have looked at the Hydraulic Oil Pump Control logic on Mark VI Control System Toolbox to try and come to a solution.
I looked at L4HQRUNZ (Main Hydraulic Oil Pump Control Enable), which I have identified as the main Hydraulic Oil Pump Control command. This signal needs to be high for the pump to work. According to the logic, the only way the pump can stop prematurely is if the lube oil pressure drops. Could you kindly verify if my assessment so far is valid? Is there possibly something else wrong here?
Thanks for all the help in advance.