after running an emissions test on liquid diesel we got an alarm that we are unable to clear and has locked the unit out. The alarm is (L86HD) on a frame 5 GE unit with a markv. can anyone help?

 

Dear butters08, you will need to review your CSP to verify your logic conforms to my suggestions below. L86HD for most Frame V machines will activate if:

The pressure switch for either gas or liquid fuel hydraulic pressure still indicates hydraulic pressure after L4 drops out, or if the liquid fuel stop valve indicates its open with L4 dropped out.

If your logic matches mine then I would recommend checking these digital inputs to see if one has not dropped out properly. Obviously since you just ran on liquid I would suspect the liquid fuel stop valve switch, (33FL), or liquid fuel hyd. switch, (63HL).

Good luck, please let us know what you find.

 

Hello over there...

L86HD alarm indicates that your GT's control oil (trip oil) pressure is low. Control oil is used in order to de-energize the final elements in case of a protective trip (via L4T) f.i mechanical over speed (L20HD, L20TV or L20FG/FL).The redundant pressure switches or transmitters (L63HG1/2/3 or A63HG1/2/3) will initiate this low pressure and you should have also an alarm associated with it. If this low pressure is genuine, you should have tripped post ignition and after detecting flame. If this low pressure was detected after ignition, the GT will not trip and you will see only the L86HD alarm. This alarm is locked via the master reset signal as long as the low control oil pressure is present.

Verify the control oil pressure on your HMI screen or via the rung display or pre-vote data display (typical setting is 4 to 6 barg).
Wrong calibrated or failed transmitters will give also an alarm (Transmitter fault alarm). It appears that you have a dual fuel GT and currently running on Diesel fuel. Investigate the root cause of the low control oil pressure. Make use of the GT Unit's PID. Normally the control oil line is coming from the Lube Oil line (8 to 10 barg) and via an orifice routed the control oil header. In case of having mechanical problem (blocked orifice, oil line blocked or one of the final elements passing such as blocked dump valve etc.) and the control oil pressure is dropping it well eventually lead to trip of the GT.

Good Luck...
A. Oztas

 

thank you guys for your quick response the problem was a 33GL limit switch everything is back to normal.