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MK VI vibration sensors
MK VI block L39VV7 (vibration start inhibit)
By Pramesh khan on 30 December, 2012 - 10:55 am

Hello dear Sir,

we have problem, we have turbogen, the generator have 3 vibration seismic sensors, one sensor is broke, no spare, we talk with the OEM, and say ok 2 sensors. try make changes in toolbox, block L39VV7, and make only 2 sensors, but always have problem (vibration start inhibit). can help please. why still no ready start, and configuration say only 2 sensors. please help.

thank you sir

Pramesh khan,

We would need a LOT more information than you have provided to be of much help.

I believe the L39VV block has been covered before on You would need to tell us what Control Constant(s) you have modified, what they were prior to the modification and what they are presently.

We would also need to know what kind of unit you have, and what ALL of the Control Constants for the L39VV7 block are to be of most help.

By Pramesh khan on 1 January, 2013 - 12:49 pm

Dear Sir, Mr CSA,

Thank you for reply. machine we have frame 9e, generator brush, before was 3 sensors, then change to only 2. make changes like this:

before, 3 sensors BB9, BB10, BB11, now have only BB10 and BB11. so in Block L39VV7, change the following parameters:-

1- VIB_IN3 change from 1 to Zero.
2- HLTH3 change to FALSE.
3- ENABLE3 is 0.
4- ALMLVL3 set to 0.
5- SD_LVL3 set to 0.
6- TRPLVL3 set to 0.

now, situation is same for BB10 and BB11, have alarm level, shutdown level, trip level, and all other constants for these inputs no change.

block L39VV7 output, have L39VD1_GEN, L39VD2_GEN and L39VD3_GEN, the first two are related to the working sensors, but L39VD3_GEN (which no use), still give problem (for removed sensor) always give alarm (vib start inhibit).

ADJ_SEL always set to False. REDPAIR also set to 0.

please help, thank you Mister.



Typically, the three generator bearing vibration sensors ar connected to the Gen. Beg. group, which is the third grouping is sensors (out of four possible groupings), which would usually be inputs 9, 10, & 11. You have disabled input 3, which is usually the #2 Brg. seismic pickup, 39VS-3.

Based on the information provided, if seismic vibration inputs are used on the three turbine bearings AND they are assigned to the first five inputs to the block (the first grouping of the block) you need to revert the "3" values back to the original values and then change the values of the failed input to reflect the failure.

Earlier versions of the block had a mask value that could be used to disable a failed input without going through what you are doing. Without knowing ALL of the block's values it would be virtually impossible to tell you exactly what to do.

Try to anticipate the questions you might be asked; provide as MUCH information about what you've done and what the results were; remember we are not there seeing what you're seeing and we don't have the luxury of looking at the configuration of your unit. If you want faster, more concise results provide as much information in your original post as possible. While you have provided some additional information, it is not enough.

And just because the third of three generator seismic pickups failed, it doesn't necessarily mean that failed input is assigned to the third input of the first grouping of the block.

By Pramesh khan on 9 January, 2013 - 1:23 am

Mr. CSA, thank you for help.

when looking at the previous configuration in the block 39VV7, the firrst 3 sensors were enabled,VIB_IN1, VIB_IN2, VIB_IN3 we assigned to the 3 sensors. and 3 channels were enabled, ENABLE1, ENABLE2, ENABLE3 were set to 1.

current configuration,we remove one sensor (no. 3). this is what done:-

1- VIB_IN3 is 0. no input assigned.
2- HLTH2 is set to FALSE.
3- ALMLVL3 is set to 0.
4- SD_LVL3 is set to 0.
5- TRPLVL3 is set to 0.

from the OUTPUT side of the V39VV7, it is like this:-

1- ALARM3 is FALSE (not connected to any other signal.
2- SD3 is FALSE, not connected to anything.
3- TRIP3 is FALSE, not connected to anything.

despite the fact we need removed the 3rd sensor, and made unused, the 39VV7 still believe that there are still 3 sensors. and it always initiates the following alarms:-

1- L39VD1_GEN is always true. Gen vib Sensor disabled.
2- L39VD3_GEN is always true (VIB start inhibit).

Can you please tell me what I am missing here if possible?

appreciate your help Sir.

Thank you

Pramesh khan,

VIB_IN1 bb1 39VS-1 (Brg. 1)
VIB_IN2 bb2 39VS-2 (Brg. 1)
VIB_IN3 bb3 39VS-3 (Brg. 2) Gas
VIB_IN4 bb4 39VS-4 (Brg. 3) Turb. Group
VIB_IN5 bb5 39VS-5 (Brg. 3)
VIB_IN6 ---
VIB_IN7 ---
VIB_IN8 --- Red. Gear
VIB_IN9 --- Group
VIB_IN10 bb10 39VS-10 TE Gen #1 (Brg. 4)
VIB_IN11 bb11 39VS-11 TE Gen #2 (Brg. 4) Gen. Group
VIB_IN12 bb12 39VS-12 TE Gen #3 (Brg. 5)
. Steam Turb.

This would be a typical Frame 9E vibration configuration for the seismic (velocity) vibration pick-ups connected to the Mark VI and passed to the L39VVn block.

NOTE: The 'Belfort Bunch' seem to take great joy in re-arranging the inputs and groups. It may well be that since your machine is a Frame 9E and it might have been "engineered" in Belfort that the inputs are assigned differently. Why? Because they can.... There's not much more to say about this--except for anyone with a Frame 9E engineered by GE EPE (Energy Products-Europe) in Belfort, France, to be aware their configuration (and sequencing/application code) can be VERY different from other, "standard" GE-designed heavy duty gas turbines.

You might also look at the Control Specification drawing provided with every Speedtronic turbine control panel for more information about the vibration detection and protection. It's usually located in Sect. 09.

You can see from the above that in the typical Frame 9E configuration, the third generator vibration sensor, 39VS-12, bb12, would be assigned to VIB_IN12--NOT VIB_IN3.

But, we can't know from the information provided exactly how the block and inputs are configured at your site. However, it would seem the problem is that you are disabling the third input to the block because the third generator sensor is failed, and the third generator sensor is probably NOT assigned to the third input to the block. So, that's why the block is still saying there is a failed input.

A failed input when shut down means there is a problem with the circuit (usually an open circuit or extremely high resistance). You might try measuring the resistance of one of the working sensors (after it's disconnected from the Mark VI) and then using a resistor of similar value across the bb12 input terminals and see what happens. But, I don't know what will happen when the shaft starts turning and there's no voltage feedback from the resistor. It's likely that it will alarm or trip again. (The "test" which is run when the shaft is not turning is to inject a small amount of current (voltage) through the circuit/sensor to make sure the circuit and sensor are connected and capable of working providing a voltage feedback to the Speedtronic. Once the shaft starts turning, the current (voltage) is removed because the sensors are passive, meaning they generate a small voltage based on the vibration and there is always some vibration when the shaft is turning.)

There are also usually redundancy "masks" and utilization "masks", which are used to tell the algorithm (block) which groups of sensors which sensors are to be used for that group, and which sensors are redundant (like bb10 and bb11 are redundant sensors on Brg. 4, the Turbine End Generator Bearing).

Some versions of this block also had the ability to temporarily disable inputs, just for situations like yours. But, without being able to see the application code running in your machine, it's impossible to say if the block has this capability or not--or how to make use of it.

This is all that's possible to say based on the information provided and the typical seismic vibration configuration. And, without being able to see what's running in your machine this is all that's possible to say.

I would suggest you have someone knowledgeable come to site to help with the problem. I would also suggest that the cheapest--and likely the fastest--solution is to obtain a new sensor and install it.

Hope this helps! Please write back to let us know how you fare.

By bicycle mechanic on 9 January, 2013 - 7:56 pm

I have not read the full thread to this, but I have a story to share that is somewhat related.

While observing system checks, at a site in Arizona by a company with a Canadian sounding name. The technician connected onto the vibration IO board with his company issued hand held signal generator. I was somewhat alarmed, because his connection was in parallel with the the vib sensor on that terminal.

Its not hard to imagine what could happen, and it did. As he manually increased the pot setting of the oscillator, its coupled impedance created a direct short circuit, causing a blown channel on a BENTLY NEVADA. This signal was also routed to the MKVI via EGD and caused an inhabit start.

The technician was baffled, he could not clear the alarm. I swear.. the air quality in the PEC had a suddenly changed for the worst.

What was not realized then, this signal was latched because a threshold level was exceeded.

Without knowing or understanding what had happen, the plant operator stood the cost for replacement card module.

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

Dear Pram,

If want to remove on of vibration from mark-VI, please open the toolbox Mark-VI then previllege level 2.

then right click one of tag to modify at Vibration card (TVIB). example vib_in3 --> delete signal connection name then OK.

after that open L39VV7 then delete vib_in3, HLTH, ALmLVL, SDllvl, trplvl then compile --> build and download

Experts, will you comment?

I have seen a few of these csp s before. What ABB described and the original author of this thread was, in my opinion, removing one sensor from the IO block without taking into account its use and inter-connectivity within the CSP.

I don't have any memory of seeing vibration sensors parallel in MKVI application, such that simply taking out one, will not affect the CSP flow on START UP!

Just a mechanic trying to get understanding.

What ABB described is a very lengthy and unnecessary method of temporarily disabling a vibration sensor that does not take into account redundancy or grouping.

A single Control Constant change (the name of which varies with the version of Speedtronic) would temporarily disable the input and reconfigure the redundancy for that group, if necessary. That's why the original poster was continually referred to the Control Specification, Section 09, for more information specifically for the version of Speedtronic at that site.