Analysis of occasional failures of ship side pushers and the characteristics of their winter operation management
MODEL: TCT-240
TYPE:CPP 4 BLADES X 2400MM
Maker:KTE CO. LTD
Motor Rated Capacity:2500 Kw x 893 rpm
introduction:
The new ship, launched for more than three years, has been running normally on the bow side push (B/T: BOW THRUSTER). However, when calling at several Japanese ports in February and March of a certain year, there were successive system start failures (OVER TRIP), resulting in unusable equipment. But when the ship sails to a port in Southeast Asia, the equipment can occasionally be started and used normally. In the event that the crew inspection system was fruitless, the service engineer was asked to solve the fault on board, but when the ship returned to the Japanese port, the fault remained unresolved.
analyse:
When the B/T's main motor is started, all the prerequisites should be met: the ventilation system (VENTILATION FAN), the hydraulic starting pump (PRIME PUMP) are already in operation, and the pitch controller has been placed in the zero position. However, when the main motor start button is pressed, the system displays "PHASE ALARM" and the system automatically unloads and alarms (OVER TRIP).
The marine side pusher is equivalent to a pitch changing paddle unit, which is powered by a 2500KW three-phase motor that rotates in the circumferential direction of the blade through the gear drive system, while the hydraulic starting pump (PRIME PUMP) provides the power of the radial rotation of the propeller to achieve direction change and pitch.
After the failure occurred, the marine service engineer has checked the software and hardware in the system and confirmed that there is no abnormality, so I judge that it should be related to the use of the equipment.
In my personal experience, every February in the North Pacific, the sea temperature in the Sea of Japan is between 4-16 degrees, and the temperature of most of the B/T system oil submerged in the water is about 10 degrees.
The oil distribution throughout the system is as follows:
A total of 650 litres of fluid are required to meet the normal operation of the entire system, of which the internal oil volume of the thruster is 560 litres
The system has a high fuel tank volume of 130 liters, and the actual oil volume in normal operating conditions is about 85 liters.
The prerequisites for the main motor of the side pusher to start operation are the head cabin cooling fan (FAN RUN) and the hydraulic oil pump (HYD. P/P.RUN) stable operation signal.
When the helm has activated the hydraulic oil pump and fan, the control dual of the side push controller is usually placed in the "zero" position. The hydraulic oil in the system only circulates between the pump and the high-mounted tank (85Ltr.), while most of the cold hydraulic oil remains in the inner cavity of the side pusher (560 Ltr.) But there is no circulating heating.
When the head car is tested, the "control dual" leaves the "zero" position, and a large amount of cold oil in the inner cavity of the side pusher will be mixed in and circulated between the oil pump and the inner chamber, and the oil pump will "trip" due to the high viscosity of the fluid! The main motor of the side pusher will also protect the "trip" immediately. At this point, you can start the main motor again after starting the reset oil pump, but only two chances, after which the system will have at least 30 minutes of automatic downtime to protect the main motor from overheating damage.
Based on the above analysis, I put forward suggestions for improvement of the operating method of the system and solved the original problem.
1. When the driver's station notifies the one-hour preparation, start the standby generator, keep the 3 units in parallel (2800kw x3), and transmit power to the side push system.
2. Notify the driver's station to start the hydraulic oil pump intermittently 2-3 times, then turn the "control dual" to "3" degrees and run continuously for at least 30 minutes, during which time the cooling fan can be bypassed to maintain the temperature in the head cabin.
3. Turn "control dual" to "0" degree and start the main motor of the side pusher.
*According to the specific situation of the equipment, in order to ensure the normal use of the equipment, the pressure setting of the hydraulic pump can be checked and reset as needed.
9.81 MPa --pitch full; 1.96 Mpa--pitch Zero
*If the system boot failure is shown to be due to phase failure, the "phase fail delaytime" can be appropriately extended on the side pusher distribution screen (but not greater than the manufacturer's allowed time: 4 seconds), or reduce the system undervoltage setting to 80-90% (the manufacturer recommends allowing the minimum setting of 70%).