Trends and historian
Цель: Изучить тему «Trends and historian» и закрепить её практическими заданиями и самопроверкой.
2 акад. часа чтение и разбор теории, решение задач, работа со схемой или виртуальным стендом и проверка понимания.
Основной материал
Trend shows value vs time and is one of strongest diagnostic tools. Compare PV, SP, controller output and valve position to understand loop behavior. Historian stores time-series data for analysis, reporting and incident investigation.
Sampling/compression
Historian may not store every PLC scan; it uses periodic sampling and compression/deadband. Excessive compression can hide fast events, while too little creates data volume.
Time synchronization
All systems must share correct time. Otherwise sequence of events becomes unreliable during investigation.
Практическая работа
Create trend set for temperature loop: SP, PV, TIC output, steam flow, valve position, inlet temperature. Explain what each adds.
Самопроверка
• Why trend useful?
• What historian stores?
• What is compression?
• Why time synchronization critical?
• Which variables compare for valve stiction?
Что нужно запомнить
- Trend shows value vs time and is one of strongest diagnostic tools.
- Compare PV, SP, controller output and valve position to understand loop behavior.
- Historian stores time-series data for analysis, reporting and incident investigation.
- Historian may not store every PLC scan; it uses periodic sampling and compression/deadband.
- Excessive compression can hide fast events, while too little creates data volume.