HELLO

We have Gas turbine Frame-V with MARK-Vie control system and turbine is in running condition.

One alarm is appearing frequently "Vibration high" BB3 in generator on its HMI. We checked the vibration Device and we found it not well. Then we decided to change it. We forced BB3 corresponding device vibration in 0.18 in/mm and we disconnect the cable from the sensor. the turbine tripped.

Please We want to know, why the turbine tripped after all BB3 is congeal by forcing the value in 0.18 in/mm.

Thank you

 

0.18in/mm???? 0.18inches per millimeter???

 

maatallah,

Without being able to see the configuration values (parameters) in the Mark VIe, and without knowing if the bearings have redundant vibration sensors, it's not possible to say for sure exactly why the turbine tripped.

The Vibration algorithm (block) used in most Speedtronic panels has the ability to be configured for redundant and non-redundant seismic (velocity) vibration sensors. In addition, most of the time (when the block parameters are properly configured--and all to often they are NOT properly configured from the factory or by the field personnel commissioning the turbine control systems) the vibration sensors are grouped (turbine; load gear (if present); driven device (generator; compressor or pump; etc.). So, there can be many kinds of configurations which can prevent the loss of a single sensor from tripping the turbine.

However, one thing that's for certain: if the circuit is opened (such as when you disconnected one of the two wires of the circuit (loop)), the Mark VIe does recognize that the circuit is open, indicating a failure of the sensor/circuit. And, depending on the Vibration algorithm configuration it may, indeed, result in a trip.

I would suggest you contact the packager/supplier of the Mark VIe, provide them with the Vibration algorithm configuration parameters currently in use in the Mark VIe, tell them about how many vibrations sensors are installed on each bearing of the entire unit, and ask them to check to make sure the configuration parameters accurately reflect the groupings and redundancy necessary for safe operation of the machine at your site.

Please write back to let us know how you resolve this problem.

 

First check the configuration whether the sensor have the OR logic or AND logic. For vibrations monitoring system like Bently the factory set configuration is OR it means the turbine will trip for any of the vibration (1 out of 2) getting high value.

Also check whether the analog value has been forced or the relay value which is actual cause of trip has been forced. Forcing the analog value will be of no use

 

Maatallah... Is vibration frequency in sympathy with rotor-rpm or rated line-frequency, if the two are different?

Regards,
Phil Corso