Today is...
Friday, April 19, 2019
Welcome to Control.com, the global online
community of automation professionals.
Featured Video...
Featured Video
Wiring and programming your servos and I/O just got a lot easier...
Our Advertisers
Help keep our servers running...
Patronize our advertisers!
Visit our Post Archive
GE frame V Gas Turbine Starting Device Trip
GE frame V gas turbine trip due to starting device trip at 2200-2300 rpm during startup where as starting diesel speed is 1900 rpm.it happens 4 to 5 times during startup.
By SANJAY MALLIK on 15 April, 2019 - 3:40 pm

why our GE frame V gas turbine trip due to starting device trip at 2200-2300 rpm during startup where as starting diesel speed is 1900 rpm. After firing its average temperature (TTXC) increases and when it reached to 507 TTXM degree Celsius, it control mode change from startup to temperature control mode and FSR was 18.2%. At 2200 rpm turbine get trip due to starting device trip. CPD value was-0.12 bar, FSRG was 5.57%, FSG was 14.57%, FPRG1 was 6.07 bar, FPG1 was 6.63 bar. CSRGV was 42.0 deg, CSGV was 41.9 deg. Our control system is MARK-IV speedtronic control system.

Please give us some idea what might be the probable cause of this tripping.

Thanking you
email id is : sanmlk2013@gmail.com

1 out of 1 members thought this post was helpful...

SANJAY MALLIK,

You need to look at the rung for the Starting Device Trip alarm to determine what condition might be causing the Mark IV to trip the unit. I think the signal name might be L4SMT, but if I recall correctly there is more than one signal which can cause the trip--so you need to determine which one of the multiple signals that can actuate L4SMT is actually tripping the turbine.

The starting means (whether it's a diesel engine or an electric starting motor or an expander turbine) is NOT directly coupled to the shaft. Virtually no starting means could develop the torque required to break the shaft away from zero speed to accelerate the shaft for starting. That's why the torque converter is there--it's a hydraulic "coupling" (actually it's a hydraulic pump driven by the starting means, and a hydraulic motor which drives the torque converter output shaft which is coupled to the Accessory Gear which is coupled to the turbine shaft through the Accessory Coupling). The starting means can spin at a very high speed to develop a high torque while the torque converter output shaft and turbine-generator shaft spin up at much lower speeds. Sometimes, depending on the type of torque converter, at higher turbine-generator shaft speeds the speed of the starting means is higher or lower than the turbine-generator shaft speed (it just depends on the design of the torque converter). So, diesel engine starting speed is almost never going to be the same as turbine-generator shaft speed--ever, not during break away of the turbine-generator shaft from zero speed nor when the turbine generator shaft should be accelerating on its own (self-sustaining speed during acceleration on the way to FSNL).

I'm going to guess that because the unit is going on Temperature Control during acceleration that the fuel is being limited--so the turbine can't develop enough torque to add to the torque of the starting means and help the unit achieve self-sustaining speed and continue accelerating to FSNL without the torque converter assist. Some times when this happens the turbine-generator shaft speed will actually start to decelerate--and that's NOT good for the machine, not at all. There is logic called "bog down" logic which senses the decreasing speed and will trip the unit to prevent damage caused by insufficient fuel to keep the unit accelerating during starting. But, there is usually an alarm to that effect ("STARTING DEVICE BOGGED DOWN" or something similar).

If the torque converter has not been recently refurbished it could just be that the torque converter is "tired" and can't transmit the proper torque. Also, diesel engines need maintenance, too. I have seen diesel fuel filters get plugged because of water in the fuel and starve the engine of fuel--so it might be trying to put out full power but not enough fuel can get through the fuel filter. I have also seen diesel engine air filters that were so dirty they couldn't pass enough air to the engine for it to develop full torque. And, also sometimes the fuel rack mechanism just gets worn out and needs adjustment or replacement and won't let enough fuel get to the engine to develop full torque.

So, you need to find out why the unit is tripping. I'm presuming the only Process Alarm you are receiving from the Mark IV is "STARTING DEVICE TRIP." You need to find out what condition is causing that alarm. I don't know if you have Rung Display on that Mark IV (it wasn't on every Mark IV), or you will have put all the elements of the L4SMT rung (if that's the correct logic name!) on the Logic Forcing Display and watch to see which one is picking up and causing L4SMT to pick up. And, then resolve that issue.

It's either a worn out and tired torque converter, or a worn out and tired diesel, or a plugged diesel fuel filter, or a dirty diesel air filter--or some combination of the above that is causing insufficient torque to be developed or transmitted to the turbine-generator shaft. OR, it's a problem with excessive fuel flow trying to assist with insufficient torque that's causing the unit to go on temperature control during acceleration and limit the fuel. Or, it could be come combination of all of the above (happens on older machines too often).

Please write back with details of what you find. And, if you write back for more assistance, please tell us when this problem started. After a maintenance outage? After a trip from load? Did it just start?

Hope this helps!

2 out of 2 members thought this post was helpful...

Sanjay

Probably more information is required to know what was wrong at your site. Can you provide the list of process and diagnostic alarms before or after the trip? What are the maximum RPM at your site? Do you have separate speed pickups for turbine and starting diesel engine as you said turbine speed was 2200 to 2300 RPM and diesel engine speed was 1900 RPM? Did L14HA pick or unit tripped before L14HA was picked up?

Below is the sample code for "Starting device Trip" alarm.


L4DE L14HR L4 L14HA L14HSX L94X L3SMT
---|/|----|/|----| |----|/|------|/|-------|/|------------( )
| | |
L33CSE | | |
---|/|-- | |
| |
| |
L3SMTX | |
----| |--------------- |
|
|
L60BOG |
---| |------------------------

If I were you, I would have troubleshooted like this. L3SMT must be "1" for "Starting device Trip" alarm to occur.

If L14HA is picked up the only cause that can trigger "Starting device Trip" is L60BOG. L60BOG will be "1" the unit starts to decelerate. If we look at the L60BOG block, it says that TNH must be lower than (5% or more) the previous value of TNH.

If L14HA is NOT picked up i.e. "1", then either L3SMTX must be "1" or BOTH L4DE AND L33CSE must be "0". L33CSE is "0" when clutch is not engaged. L4DE will be "0" if diesel engine run permissive is not present. In this case "Starting device Trip" will occur if starting clutch is not engaged AND diesel engine start permissive is not present.

If L3SMTX goes to "1" one of the following alarms may appear.
1. Starting device lockout
2. Diesel failure to start

Please post the process and diagnostic alarms to narrow down the problem. Hope it will help.