During Cummins diesel generator set operation, low oil pressure will cause poor lubrication of all transmission components of the set. Blockage of the oil circuit will cause the phenomenon of cylinder pulling, cylinder holding, and excessive bearing clearance, which directly affects the normal use of diesel generator sets. The low oil pressure of the oil-generator set is mainly related to the following aspects: (1) Cooling system: oil cooler is blocked; the external gap of the radiator core is blocked. (2) Lubrication system: dirty oil filter; oil suction pipe blocked; oil pressure regulator failure. (3) Mechanical adjustment and repair; improper bearing clearance; engine needs overhaul; main bearing or connecting rod bearing is damaged. (4) Operation and maintenance: The engine is overloaded; the oil should be replaced in time, and the correct use of the oil filter should be ensured. Only in accordance with the correct maintenance method can the normal use of the unit be guaranteed. We analyzed the circuit of the automatic switch control panel. When the ATS control system detects the mains failure or the failure signal after the mains failure, the control system drives the control motor to move the load contact to the zero position, and through the normally closed contact of the K2 relay (closed after power failure) The diesel generator set issued a start command. After detecting the electrical signal on the unit side, the motor is controlled to close the load contact on the unit side. According to the working principle, the start command of the unit is transmitted through the loop formed by the normally closed contact of the K2 relay. It can be seen from the above analysis that the key to solving the K2 relay problem is how to solve the problem that the unit cannot start automatically after the mains is out of phase. After research, it was decided to use commonly used phase failure and phase sequence protection relays to solve this problem. The improved automatic test system circuit is shown in Figure 2. In the figure, XJ3-G is a phase failure and phase sequence protection relay, and 5-6 is a normally open contact (disconnected after power failure). If the commercial power supply is out of phase, assuming the C1 or A1 phase, the K2 relay will not be de-energized. Although the ATS control system drives and controls the motor to divide the load contact into zero, the start command cannot be transmitted to the unit and the unit cannot be started. After inquiring the manufacturer, I learned that the device is an old model and does not have the function of self-starting when the mains power fails. The working principle of the modified ATS is that when the mains power is normal, the normally open contacts 5-6 of the XJ3-G relay are closed to ensure that the K2 relay is energized. When there is a mains failure or phase loss, the XJ3-G relay will act to disconnect the normally open contacts 5-6, and then the K2 relay will be de-energized and disconnected to ensure that the unit receives the start command and starts normally!
Post time: Jun-09-2021