Could anyone explain the below situation to me?

We're using a CCC speed controller series 3+ to control our steam turbine (HHP steam pressure of 110barg). HHP steam goes through the 1st stage of the turbine then half of it is extracted to the HP steam network (39barg) while the other half continue goes through the inter-stage valve between 1st and 2nd stages of the turbine (V2). A performance controller series 3+ is designed to support the speed controller in maintaining the steam inlet pressure (HHP). The performance controller normally regulates the steam inlet valve (V1) while the speed controller regulates the V2. They're coordinating to keep both the speed and the inlet pressure at desired values. In any abnormal situation, the V2 shall be kept full open while the turbine speed is maintained by the V1.

The OUT 1 of speed controller is configured as "ActL" and there is no feedback signal from the I/H converter.

The speed controller is generating alarm "I/H failure" and "I/P failure" and can not be reset (the turbine and compressor are still running now).

We'd checked all conditions to find the causes of the alarms and could not explain. We doubt that the controller software may have problem. Has anyone experienced the same situation?

 

The Series 3 Plus speed controller has the ability to monitor an analog signal from an I/H transducer or I/P transducer to determine if the output of the device is tracking the command signal that is output from the controller. If the controller detects an error between the input and output it generates an alarm to indicate a failure. If the unit seems to be operating correctly, then the problem may be with the analog input from the transducer.

Try taking a look at the CCC Manual IM307 (around page 48)-it gives a good explanation of the alarm, setup, etc.

If you've really checked all on the inputs as you indicate and they are all good, then it must be a controller problem, but I really doubt it. Has anyone been trying to change the configuration? This might be a good place to start.