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In GE Gas Turbine speedtronic Mark VI, I want to understand how the logic function block for bearing drain temperature works? Can any body explain?
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MAHENDRA,
Each of the function blocks in Mark VI Toolbox has a type/name at the top of the box. Can you provide the function block name and describe the inputs to and outputs from the block?
Generally, for most GE-design heavy duty gas turbine, bearing drain temperatures are only monitored to alarm if they exceed a setpoint. This is usually done using a comparator block which looks at an input, compares it to a setpoint (a Control Constant) and if the input is equal to or greater than (usually) the setpoint then a logic signal is set to logic "1" which then causes an alarm to be annunciated.
There may be a multi-function comparator block which looks at several inputs and compares them to several setpoints--but the function is basically the same--if the input exceeds the setpoint set a logic signal to "1" and annunciate an alarm.
SOME--but not many--sites actually trip on "excessively" high bearing drain temperatures, but since there is usually only a single T/C or RTD in a bearing drain that is connected to the Mark VI this is considered to be poor practice because failure of the single sensor can cause a turbine trip. But, it's still done some times.
Most of the sensors installed in the bearing drains are dual-element sensors--meaning there are two T/Cs or RTDs in the single sensor that's installed in the thermowell. Usually, only one of the two T/Cs or RTDs is wired to the Mark VI, and if there's a problem with the one that's connected to the Mark VI, the interconnecting wires can be shifted over to the other T/C or RTD. This can even be done while the unit is running--though it's not really recommended if one is not familiar with the Mark VI.
If you can describe the block, it's inputs and outputs, and tell us about the problem(s) you are experiencing, we can probably provide some more assistance.
Hope this helps!
Each of the function blocks in Mark VI Toolbox has a type/name at the top of the box. Can you provide the function block name and describe the inputs to and outputs from the block?
Generally, for most GE-design heavy duty gas turbine, bearing drain temperatures are only monitored to alarm if they exceed a setpoint. This is usually done using a comparator block which looks at an input, compares it to a setpoint (a Control Constant) and if the input is equal to or greater than (usually) the setpoint then a logic signal is set to logic "1" which then causes an alarm to be annunciated.
There may be a multi-function comparator block which looks at several inputs and compares them to several setpoints--but the function is basically the same--if the input exceeds the setpoint set a logic signal to "1" and annunciate an alarm.
SOME--but not many--sites actually trip on "excessively" high bearing drain temperatures, but since there is usually only a single T/C or RTD in a bearing drain that is connected to the Mark VI this is considered to be poor practice because failure of the single sensor can cause a turbine trip. But, it's still done some times.
Most of the sensors installed in the bearing drains are dual-element sensors--meaning there are two T/Cs or RTDs in the single sensor that's installed in the thermowell. Usually, only one of the two T/Cs or RTDs is wired to the Mark VI, and if there's a problem with the one that's connected to the Mark VI, the interconnecting wires can be shifted over to the other T/C or RTD. This can even be done while the unit is running--though it's not really recommended if one is not familiar with the Mark VI.
If you can describe the block, it's inputs and outputs, and tell us about the problem(s) you are experiencing, we can probably provide some more assistance.
Hope this helps!
M
MAHENDRA
I am not experiencing any problem, but I do not know how to read this function block. As mentioned in speedtronic this block is named as " COMPHYS", having two inputs, IN1 & IN2, FUNC & OUT. It also has HYST & SENS. SENS has 54 Degree F. It seems this is set point. Now my query is what is the function of this block & how to read this block? Can any body explain it?
MAHENDRA,
Have you tried right-clicking on the block and then selecting 'Block Help'? Since this is a block and not a macro, there will be a Help screen that will pop up, with a description of the block, it's inputs and outputs, and its function. It can even be printed (or copied to a MS-Word document which can then be printed from another PC connected to a printer--use the ALT-PRT SCRN buttons to copy the active window to the Clipboard, then paste the Clipboard contents to a MS-Word document, save it to a flash drive, move the flash drive to another PC which is connected to a laser or color printer, and voila!).
The block is a COMPARE with HYSTERISIS block. It compares an input to a setpoint and depending on the type of comparison (Greater Than; Greater Than or Equal To; Equal To; Less Than; Less Than or Equal To) will set the block's output to a logic "1". Depending on the value of the Hysteresis input, the output will revert to a logic "0".
Hope this--and reading the Block's Help description--helps!
It's suggested that you copy the Toolbox manual from the HMI and have a read of it to learn how to navigate around Toolbox and use it's helpful functions.
Have you tried right-clicking on the block and then selecting 'Block Help'? Since this is a block and not a macro, there will be a Help screen that will pop up, with a description of the block, it's inputs and outputs, and its function. It can even be printed (or copied to a MS-Word document which can then be printed from another PC connected to a printer--use the ALT-PRT SCRN buttons to copy the active window to the Clipboard, then paste the Clipboard contents to a MS-Word document, save it to a flash drive, move the flash drive to another PC which is connected to a laser or color printer, and voila!).
The block is a COMPARE with HYSTERISIS block. It compares an input to a setpoint and depending on the type of comparison (Greater Than; Greater Than or Equal To; Equal To; Less Than; Less Than or Equal To) will set the block's output to a logic "1". Depending on the value of the Hysteresis input, the output will revert to a logic "0".
Hope this--and reading the Block's Help description--helps!
It's suggested that you copy the Toolbox manual from the HMI and have a read of it to learn how to navigate around Toolbox and use it's helpful functions.
