How Does the Oil Pressure Switch in the Diesel Generator Work

The simplest way to define the oil pressure switch of diesel generator is as a diesel engine protection device. The meaning of the oil pressure switch is to monitor the oil pressure of the diesel engine. This switch can usually be located on the engine block and can be found in either of two states - open or closed.

When the oil pressure is low, it can be observed that the switch is closed to ground when it malfunctions. On the other hand, if the oil pressure exceeds the minimum requirement, the switch is in the open state.

The minimum oil pressure requirement for the diesel engine to shut down is determined and set by the engine manufacturer to help prevent any problems or catastrophic failure of the diesel engine.

You know what? Many times, diesel engine manufacturers provide oil pressure switches.

Oil pressure switch - application

In most cases, the oil pressure switch is used to ensure that the diesel engine is not running before starting. Here, the switch needs to be in the default state, which is grounded. The operator checks whether the switch is in this stationary position before starting the engine to avoid engaging the starting motor when the engine is already running, as this may cause starter failure.

The oil pressure sensor also serves as an actuator. Here, once the oil pressure in the diesel engine drops below the preset critical level, it will activate the oil warning light on the dashboard. This timely signal from the oil pressure gauge helps to prevent any significant damage to the engine.

Although it may vary depending on the overall structure of the engine, the oil pressure sensor is usually located in a common area, such as the cylinder block or oil filter housing of the engine. In some cases, the oil pressure gauge can be located on the engine head.

Working principle of oil pressure switch

In most cases, the oil pressure sensor is operated by a self elastic diaphragm, also known as a movable diaphragm with a hairspring. The location of the diaphragm is a direct result of the pressure applied to it, which is why each diesel generator OEM assigns a different oil pressure threshold value to each engine, usually in the range of 3.5 to 11 psi.

When the oil pressure drops below the critical value, the oil pressure sensor activates a warning light or simply returns a signal to the ECU. This helps to promptly alert the operator to prevent any damage to the engine.

In switches with normally open contacts, the contacts are activated when the oil pressure in the engine reaches a specified critical level. This facilitates the movement of the diaphragm, causing the contacts to connect together, thus placing the switch in the closed position.

On the other hand, in switches with normally closed contacts, the contacts are deactivated when the oil pressure in the engine reaches a specified critical level. This is beneficial for the movement of the diaphragm, causing the already connected contacts to now disconnect together, thus placing the switch in the open position.

Common problems with oil pressure switches

What is the procedure for checking the oil pressure switch?

One of the simplest ways to test an oil pressure switch is to connect a multimeter between the pin and the transmitter body. When the engine is turned off, the switch should be in the off state and open when the engine is running.

What are the reasons for the decrease in oil pressure?

The loss of engine oil supply is usually caused by low or high oil viscosity. Usually, when the viscosity is very high, it will generate a high level of resistance during the pumping of oil. This can lead to a lack of lubrication within the system, ultimately leading to a decrease in pressure.

If you have other questions about the diesel generator or are ready to configure a diesel generator, please contact us by email dingbo@dieselgeneratortech.com.