Working Principle of Oil Supply System Control of Diesel Generator

In standby power stations with higher requirements, self-starting units are generally installed. When the self-starter unit is put into the emergency state, all systems of the unit need to be in the emergency state. The cooling water and lubricating oil must have a certain temperature, that is, a preheating device should be installed; in order to quickly load the machine after starting up and prevent the unit from being damaged due to insufficient lubricating oil, a pre-lubricating device should be installed; if the pressurized oil supply is used, the oil inlet valve and oil delivery pump (referring to the unit with an additional oil delivery pump) should be opened in time, and if the self-flowing oil supply is used, the oil supply pump should be automatically activated according to the oil level of the daily fuel tank to ensure the normal operation of the oil supply system.

Preheating Device

The purpose of setting up the automatic preheating device is to adapt to the rapid loading requirements of the unit after emergency self-starting and closing, and to reduce the thermal stress of a large unit when the emergency start is rapidly turned on.
The preheating device generally adopts a pipe-shaped mouthpiece, which is installed at the lower position of the cooling system of the unit and the piping of the trickling system. Through the heating of the local pipeline medium, the cooling water and lubricating oil in the machine body are self-circulated under the action of temperature difference, so as to achieve the purpose of preheating the unit. The pre-ring rolling should adopt automatic temperature control, and it will automatically start working when the unit is put into emergency state. After the unit starts successfully, the preheating device should automatically withdraw from work. The preheating temperature control range is generally designed at 35~65°C. That is, when the temperature of water and oil is lower than 35°C, the power of the tubular heater is automatically turned on, and when the temperature is higher than 65°C, the power of the heater is automatically cut off, so that the unit can always maintain a certain temperature during the emergency start-up period.
The water and oil temperature control element should be considered in combination with the thermal protection of the unit and the star device. Generally, XCT-12 moving coil regulator can be used, and its temperature sensing element is equipped with NZC or NZB type ordinary thermal or platinum thermal resistance. The high and low signals from the regulator relay are set at 35°C and 65°C respectively to control the preheating device. When the unit starts successfully, the regulator can be used as an indicator for remote measurement of temperature parameters.

Pre-lubrication Device

The purpose of setting up the pre-lubricating device is to have certain lubricating conditions during the unit’s emergency preparation and start-up period, so as to ensure the unit’s smooth start and avoid dry friction of the moving parts after starting. The automatic pre-lubricating device of the unit generally has two methods: periodic automatic pre-regulation and DC electric pump pre-lubrication.
Periodic automatic pre-preparation usually uses an electric gear pump connected to the original eyebrow oil circulation system of the diesel generator. When the unit is put into emergency preparation and starts, the oil pump starts to work intermittently, and the periodic timing oil pumping is realized by electrical control. Generally, oil is pumped every 4~6 hours, and each pump is 2~5 minutes. When the emergency start of the unit is successful, the oil pump should be deactivated. This pre-lubrication method is easy to control and easy to refit the lubrication system, so it is widely used.
The DC electric pump and tearing device adopts a gear oil pump driven by a DC motor and is connected to the original lubrication system of the diesel generator. The oil pump is powered by 24V DC storage battery. The working conditions are as follows: when the external power is interrupted, it is controlled by the self-starting device, and the pre-lubricating oil pump is first started to pump the oil for a few seconds to tens of seconds, and the standby unit starts to start the propeller oil generating set when a certain lubricating oil pressure is established. When the unit is started by remote control, the pre-lubrication oil pump can be manually started remotely to establish the necessary lubrication conditions. The advantage of this approach is that it is easy to control and no pre-lubrication is necessary during emergency preparedness. The disadvantage is that the use of DC power supply increases the burden on the starting (control) battery, and the time for emergency self-starting to restore power supply is relatively prolonged.

Control of fuel supply system

In the unit with emergency self-starting function, it is necessary to ensure that the fuel supply path is unimpeded during emergency starting and after starting, so automatic control measures must be set to meet the requirements.
Usually, the diesel generator oil inlet adopts self-flowing type, and the position of the daily fuel tank should be higher than the oil inlet of the diesel generator. A manual oil valve is usually installed between the daily fuel tank and the diesel generator oil inlet.