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hi i work in a power plant as operator and sometimes a diag alarm appear in HMI TCCA 4-20ma out of limit and i look for an interpretation for this message; the control system are MK V.
Hi,
The TCCA card is an analog input/output card in Loc. 2 of the <C> core.
The <C> core 4-20 mA analog inputs and -outputs are terminated on the CTBA terminal board (Loc. 6) of the <C> core (that's the terminal board with the StageLink coaxial terminals on it).
This alarm usually occurs when a 4-20 mA input or -output drops much below 4 mA or much above 20 mA. I have typically seen this alarm on 4-20 mA outputs which have an "odd" configuration, such as when one of the outputs is used for a speed signal and is scaled from 90-110% of rated speed, and when the speed is less then 90% this alarm is annunciated. Or, when one of the outputs is used for exhaust temperature and the output is scaled at 500-1100 deg F and when the exhaust temperature is less than 500 deg F the alarm is annunciated.
Most times these 4-20 mA outputs are used to drive meters on a remote panel or as 4-20 mA inputs to a DCS or PLC.
You need to have your instrumentation & control technician have a look at the alarm message (it's probably much more specific as to the exact input or output which is out of limits) and then have a look at the I/O Report (filename F:\UNIT1\TC2KREPT.TXT) and determine which input or output is the problem and then why it might only be out of limits at certain times.
Hope this helps!
The TCCA card is an analog input/output card in Loc. 2 of the <C> core.
The <C> core 4-20 mA analog inputs and -outputs are terminated on the CTBA terminal board (Loc. 6) of the <C> core (that's the terminal board with the StageLink coaxial terminals on it).
This alarm usually occurs when a 4-20 mA input or -output drops much below 4 mA or much above 20 mA. I have typically seen this alarm on 4-20 mA outputs which have an "odd" configuration, such as when one of the outputs is used for a speed signal and is scaled from 90-110% of rated speed, and when the speed is less then 90% this alarm is annunciated. Or, when one of the outputs is used for exhaust temperature and the output is scaled at 500-1100 deg F and when the exhaust temperature is less than 500 deg F the alarm is annunciated.
Most times these 4-20 mA outputs are used to drive meters on a remote panel or as 4-20 mA inputs to a DCS or PLC.
You need to have your instrumentation & control technician have a look at the alarm message (it's probably much more specific as to the exact input or output which is out of limits) and then have a look at the I/O Report (filename F:\UNIT1\TC2KREPT.TXT) and determine which input or output is the problem and then why it might only be out of limits at certain times.
Hope this helps!
