What Common Faults in Generator Electrical and Control Systems ?

What Common Faults in Generator Electrical and Control Systems ? 

Abstract: With the continuous increase in electricity demand, the management, operation, and technical level of diesel generator sets in enterprises during daily work have gradually attracted users' attention. This article provides a detailed analysis and handling methods for faults that occur during the actual operation of diesel generator sets, hoping to offer effective references for diesel generator operators.

In the equipment composition of a diesel generator set, the driving device is the engine, and the device that converts kinetic energy into electrical energy is the alternator. These two main components play a decisive role in the actual operation. However, various factors can also easily cause operational failures. Generally, generator failures are divided into electrical faults and mechanical faults. Electrical faults typically include excessive motor temperature, internal short circuits in the unit, faults in the measurement and control circuits, and operational failures caused by harsh environments. Mechanical faults usually include bearing failures, bearing neck damage, bearing keyway damage, and coupling gap failures.

I. Diesel Generator Fails to Start

Loss of battery power;

Starter motor failure;

Magnetic starter failure;

Fuel shut-off valve failure;

DC monitoring board failure;

Air in the diesel pipeline;

Fuel pump failure.

II. Generator Has No Voltage Output or Excessive Voltage Fluctuation

PMG stator or rotor damage;

AVR board damage;

Diode assembly damage;

Exciter rotor or stator damage;

Main generator stator or rotor damage;

Short or open circuit in P2, P3, P4 lines;

Short or open circuit in P6, P7, P8 lines;

Short or open circuit in X, XX lines.

III. Oil Pressure Alarm Under Normal Oil Pressure Conditions

Oil pressure alarm failure;

Grounding of oil pressure alarm wiring;

DC monitoring board failure.

IV. High Water Temperature Alarm Under Normal Water Temperature Conditions

Water temperature alarm failure;

Grounding of water temperature alarm wiring;

DC monitoring board failure.

V. Control System Faults Problem Solve 

Q : Controller Shows No Water Temperature/No Oil Pressure/No Liquid Level, Displaying "####".
A : Check the controller's temperature/oil pressure/liquid level sensors and their wiring to see if "G" and "WK" are reversed.

Q : Controller Displays Inaccurate Water Temperature/Oil Pressure/Liquid Level Data.
A : Check the curve type of the controller's temperature/oil pressure/liquid level sensors to ensure it matches the selected sensors.

Q :Controller Displays Unstable Water Temperature, Oil Pressure, and Liquid Level Data.

A : 
(1) Single-end ground the common terminal of the sensors on the controller to the generator set's grounding terminal.
(2) Check if the negative cable of the starter motor is too thin, causing voltage fluctuations during startup.

Q :Controller's Start Output Port Frequently Burns Out.
A : The internal start relay of the controller is small and has limited current capacity. However, during startup, the current can be 2–3 times the relay's rated current. While short startup periods may be tolerable, repeated prolonged startups can cause the relay contacts to weld together. Therefore, an external relay must be added for starting.

Q :No RPM Display During Startup, Showing "0 rpm" or No Display.
A :  Check the RPM sensor itself, its installation position (whether it is too far from the flywheel plate), inspect the wiring, and verify the controller's startup success condition settings.

Q :Generator Set Has No Idle Speed or Directly Over-speeds, Controller Reports "Overspeed Alarm Shutdown".
A :

(1) Check whether the controller's programmable output ports are configured.
(2) Determine whether the unit uses electronic speed control or mechanical cable speed control.
(3) Check the external electronic governor for faults and wiring issues.
(4) Verify if the controller's idle timer is set to "0S".
(5) Adjust the "rated speed" of the electronic governor by turning the potentiometer counterclockwise to reduce the speed.

Q :Generator Set Cannot Reach High Speed, Controller Reports "Underspeed Alarm Shutdown".
A : 
(1) Check whether the controller's idle control output port disconnects after the idle timer expires.
(2) Check the electronic governor for faults and wiring issues.
(3) Verify if the "rated speed" setting of the electronic governor is too low.
(4) Check whether the acceleration time adjustment of the electronic governor board is set too high.