【New user’s question】What is the difference between PAHH and PSHH on the PID diagram?
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Pahh has already stopped operating due to excessive pressure; then what is the purpose of Pshh? How are the two used together?
One is for alarm, and the other is for interlock switch. A should trigger the alarm while S brings about the vehicle’s stoppage; of course, what you see is only the alarm, but in reality there is a sequence to it – the alarm is triggered at the same time as S causes the vehicle to stop
On the PID diagrams I’ve seen, there are usually three instruments: PAH, PAHH, and PSHH. First, the PAH triggers an alarm and the PSHH causes a shutdown; so what is the function of PAHH?
Let me put it this way: when the interlock value is reached, a high-level alarm is issued and the system shuts down via interlocking; the shutdown signal is sent to the equipment, while the alarm is there for your visibility
The high alarm PAH was shown to me； The high alarm pahh is for the chain parking system pshh to see.
You can understand it that way as well; in any case, when an overreporting occurs, a pop-up will appear. However, in some cases, an overreporting triggers the interlock switch to cause the system to shut down, while in other cases there is no such interlock mechanism
PSHH should refer to the actual switch, while PAH and PAHH denote those shown in the DCS alarm display. PSHH and PAHH are the same process variable.
PSHH should refer to a interlocked switch, while PAH and PAHH denote those shown in the DCS alarm display. PSHH and PAHH are the same process variable; shutdown is triggered simultaneously upon alarm.