11 - AUTO 1 - Function and Perfomance test of Systems and Devices.pdf

Instructor: C/E R.S. Pantoja Subject: AUTO 1 Period: Semi-finals Semester: First Topic 5: Function and Performance Test of Systems and Devices Learning Outcome: LO4.4 Perform performance tests on protective devices to ensure that they function as intended, including test on alarm trips and safet...

Instructor: C/E R.S. Pantoja Subject: AUTO 1 Period: Semi-finals Semester: First Topic 5: Function and Performance Test of Systems and Devices Learning Outcome: LO4.4 Perform performance tests on protective devices to ensure that they function as intended, including test on alarm trips and safety interlocks in accordance with the manufacturer’s manual. Course Outcome: CO4 Demonstrate the function and performance test in accordance with the manufacturer's standards for the: Monitoring Systems; Automatic control devices; and Protective devices. Marine Diesel Engine Safety Devices Marine diesel engines are critical machines on ships and their safe operation is paramount to ensure the safety of the crew, passengers, and vessels. To help mitigate risks, several safety devices are essential for marine diesel engines. The following are some of the most important safety devices, such as the Crankcase Relief Door, Oil Mist Detector, Scavenge Relief Valve, Starting Air Relief Valve, Cylinder Head Safety Valve, Starting Airline Flame Trap, and Cylinder Relief Valve. In addition to these safety devices, there are also safety alarms such as low oil pressure alarms, high water temperature alarms, fuel filter alarms, exhaust gas temperature sensors, and emergency shut-off switches. By understanding the role of these safety devices and maintaining them properly, you can help ensure the safe and reliable operation of the marine diesel engine. Main Engine Alarms and tripping devices Main engines are guarded against any abnormality in the engine by alarm and tripping devices. The following nineteen types of alarm and tripping devices are popularly installed on the engines.  Low Lubricating oil pressure trip  Engine over-speed tripping device  Low jacket cooling pressure trip  Main bearing high-temperature trip  Piston cooling low-pressure trip  Camshaft Low lube oil pressure trip  The high-temperature thrust-bearing trip  Oil mist alarm  Emergency manual trip  Low sump oil level alarm  Lubricating pump tripping alarm  High jacket water alarm  High piston cooling alarm  Low-control air pressure alarm  Low starting air pressure alarm  High exhaust gas temperature alarm  Engine turning gear engaged alarm  High turbocharger gas temperature alarm  High scavenge temperature alarm A typical Alarm System will have a sensing device such as  A level sensor  Thermocouple  Pressure sensor. These sensing devices are connected to display devices which may have minimum and maximum values marked on them. When this value reaches, a switch is activated an electrical or pressure signal is sent to the sips alarm panel and audiovisual warning devices. The panel’s indicating light will remain on or continue flashing till the duty engineer acknowledges the alarm and the condition that caused the alarm to activate has been removed. It is a protection circuit as well warning circuit. The activation of the limit switch will also activate the shutdown procedure of the machine. The protective system activates one or more switches or valves, causing the machine to come to an unscheduled halt in a controlled manner. Safety trips and critical alarms for the Engine safety. Important Guide Lines Carry out the alarm system maintenance periodically for the proper functioning of the sensors and alarms. If the alarm indication appears, ascertain the cause of alarm and then press the reset button. While adjusting temperature and pressure switches, follow the following.  Use the calibrated instruments when adjusting the switches. And the direction of change is taken into account.  After the adjustment, constantly repeat the test at two different values.  Whenever an automatic restart set is involved, in the machine control room, always switch the automatic restart circuit to manual and off before re- set.  Never restart the equipment or put it back into service without rectifying the cause of alarm.  Always investigate any abnormal run indication even if the equipment is running smoothly.  The watch-keeping engineer must have enough confidence in the alarm system and protection devices in the engine room. He must be sure all the time that he will be given a timely warning to take immediate action. 1. Over-speed trip: An over-speed device will cut off the fuel supply in the speeding Engine event more than the predetermined value. Set the overspeed setting by manual setting It will not allow the Engine to restart as the reason for overspeeding still exists, and the Engine might run over speed again. To ensure the correct operation, maintenance staff should check it periodically. As per the practice following two types of over-speed devices are installed.  Mechanical over Speed Trip is set at 18% more than the nominal operating RPM (Speed).  The setpoint of an Electro-pneumatic device is 15% above the Engine’s Nominal RPM (speed). 2. Jacket water high-temperature Alarm and Trip:- Jacket cooling Water removes the waste heat. Failure of jacket water to remove the heat away, seizure of the components will take place due to expansion. The alarm will indicate the abnormal temperature at the initial stage and will trip the engine in the event of ignoring the alarm. 3. L.O low-pressure Trip, alarm and Trip:- There will be instant engine damage due to the low Lube oil pressure. A standard lube oil pressure device will stop the Engine. The low lube oil pressure will cause the seizure of components. There will be the failure of Major components like the Crankshaft, Bearings, and Pistons due to the Low lube oil pressure. Usually, oil pressure stops the Engine. There are two set points for low lubricating oil pressure. First, setpoints will give the alarm of low Lube oil pressure. The second set point will stop the Engine to prevent significant damage to the Engine. 4. High Exhaust gas Temperature:- High exhaust gas temperatures are too critical and can provide information regarding the Engine operation. High Exhaust Temperature will indicate the symptoms of overloading of the Engine. High exhaust temperature will also display insufficient scavenging in the machine. Severe damage may take place if the Engine continues to operate at High exhaust temperature. Therefore High exhaust temperature alarm is provided. 5. Oil Mist Detector Oil Mist Detectors protect large diesel, gas, and dual-fuel engines of all applications. They protect against heavy consequential damage due to oil mist explosions, a result of overheating of bearings or moving parts. The oil mist detector is the essential device fitted on Marine Diesel Engines for the safety of Engines. The oil mist detector will check and monitor the mist in the crankcase. Types of safety Devices 1. Alarm: An Audible and visual alarm will ring if there is any deviation in the Parameter. The notice will give a pre-warning of the problem. 2. Slow down: In this process, if the action taken by the Engineer is not appropriate then the device will slow down the engine. 3. Shut down: For any higher fluctuating parameter that could be the cause of harm to other engine systems, the shutdown protective device will cut off the fuel system and stop the Engine. 4. Starting Interlock: Starting Interlock will not allow the Engine to start if the Engine’s crucial system hasn’t been operated. It will also interlock the system if the turning gear is appropriately arranged. Safety Items Fitted to the Main Engine and How They Work Typical Safety alarms Operation Data and Set Points Different Engine Slow Down Situations (Critical alarms and safety trips) Under the slowdown situation, Engine speed will fall below the minimum rate but above critical speed. Conclusion: Among the most important safety devices are the engine shutdown system, emergency stop button, overheat protection, and relief door on the crankcase. These devices can help prevent engine damage, fires, and other emergencies, and give crew members the means to quickly stop the engine if needed. Regular maintenance and testing of these safety devices is essential to ensure they are functioning properly and can provide the protection they were designed for. References: https://marinediesel.co.in/marine-diesel-engine-safety-over-speed-trip/ ***END***