| dc.description.abstract | Suggested Topics: Electronic overspeed detection system (speed sensors and logic devices)
Number, logic
Speed sensing gear
Sensor type
Electro-hydraulic solenoid valves
De-energize to shutdown (API default)
Number, location, orientation (vertical or horizontal)
Built in position sensor
Detection system to alarm on failure of the coil; change online
Capable of on-line testing without defeating trip protectionEmergency trip valve(s)/combined trip and throttle valve(s)
"Mechanical latch type" and "Oil operated/actuated type"
Periodic online exercising - partial stroke test (frequency)
Full instrument loop "proof" test (frequency)
Valve overhaul (repair shop, overhaul frequency, etc.)
Systems with duplicate trip valves arranged in parallel
OEM upgrades (i.e. metallurgy, etc.)
Non-return valve on extraction turbines
Overspeed initiates a signal to close non-return valve
Types (spring-loaded hydraulic actuated cylinder; pneumatic actuated cylinder)
Valve overhaul (repair shop, overhaul frequency, etc.)
Testing
Mechanical overspeed system
Test frequency | en |
