Fail-safe design and de-energize-to-trip concepts
Цель: Изучить тему «Fail-safe design and de-energize-to-trip concepts» 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
Fail-safe means system moves to or maintains safer state upon specified failure. It does not mean every valve should fail closed. Safe state depends process.
De-energize-to-trip
Some shutdown circuits are energized in normal condition; loss of power causes trip. This helps detect wire break/power loss, but introduces availability considerations. Redundant architectures may balance safety and spurious trips.
Практическая работа
For fuel valve, cooling valve and depressurization valve discuss possible safe positions. Explicitly note that final decision requires hazard analysis.
Самопроверка
• What is fail-safe?
• Does fail-safe always mean closed?
• What is de-energize-to-trip?
• What is spurious trip?
• Why process analysis required?
Что нужно запомнить
- Fail-safe means system moves to or maintains safer state upon specified failure.
- Some shutdown circuits are energized in normal condition; loss of power causes trip.
- This helps detect wire break/power loss, but introduces availability considerations.
- Redundant architectures may balance safety and spurious trips.
- For fuel valve, cooling valve and depressurization valve discuss possible safe positions.