How to Fix Diesel Generator Not Producing Power Problem?

Nowadays, diesel generators serve as a reliable and efficient backup power source during outages and also provide electricity in areas without access to the power grid. They may be used for more complex applications. However, diesel gensets are susceptible to problems during operation due to a variety of reasons. One of the most common problems is the generator runs but doesn’t produce any power. In this article, we’ll explore the common causes and solutions for the diesel generator not producing power issue.

1. Loss of residual magnetism

Loss of residual magnetism can be considered as one of the most common causes of a generator producing no power. Diesel generators with a self-excited alternator rely on the residual magnetism of the alternator, left from it being run previously, to build up its initial voltage. Diesel generators don’t have magnets. Instead, they rely on conductors to create a magnetic field by turning the output voltage into a direct current which they funnel through a coil, resulting in an electromagnetic field. As the engine begins to turn this electromagnet, moving its electric field, through the stator windings, your generator will produce more power. When the generator is shut off, it retains some of this magnetic field, which is known as residual magnetism. Your diesel generator set relies on this residual magnetism to start up the next time you use it. If there is no magnetism, the generator will run without producing any energy.

Generally, the generator loses its residual magnetism due to a lack of use, running for too long with no load, damaged conductor components or being shut off with a connected load. If your diesel generator is new, it may also lose residual magnetism due to the long distance transportation vibration.

Solution: If you measure the voltage across the phases of the alternator and find the voltage is 0-5V per phase, it is probably a loss of residual magnetism. To fix the problem, you can regain residual magnetism by using a 12 Volt generator battery, a jump starter pack or a corded electric drill. To prevent the loss of residual magnetism, it’s suggested that you run your diesel generator regularly and remember to switch off all the loads before turning off the generator.

2. Poor connections

Poor connection is also another common cause for generator not producing power. If your diesel generator runs but fails to produce electricity, improper connections may be the culprit. This could happen when your generator is out of use for a while and the ports may be blocked by dust or debris. Sometimes, loose or frayed wires could affect the connection and interfere with the generator’s output.

Solution: Perform a visual inspection and identify what is the cause of the issue. If there is any dust or debris, or if something is blocking the ports of the generator, clean it. Make sure all the connections are proper. This can maximize the reliability of your generator. If you are not an experienced electrician, it’s suggested that you ask a specialist for help rather than deal with the damaged wires by yourself.

3. Excitation circuit wiring error or blockage

Sometimes, an excitation circuit wiring error or blockage can also cause the problem.

Solution: If an excitation circuit is blocked, you can fix the issue by using a multi meter to find the blocked excitation winding and reconnecting it. If poor contact contributes to the problem, you need to polish and smooth the surface oxide layer to repair poor connections.

4. Tripped or damaged breaker

Faulty circuit breakers can also interfere with a generator's output. Circuit breakers are important safety devices which can cut the power when a surge or overload occurs. They trip and disconnect the supply to the circuit when detect a current in the circuit over a certain limit. This helps to protect you from shocks and prevent fires. If you overload the breaker with a lot of appliances, or there is a ground fault, the breaker will trip. As a result, you won’t get any output at the outlets of the generator. In addition, if there is something wrong with the breaker itself, the circuit won’t get electricity either.

Solution: Check the circuit breaker and identify the issue. If the circuit breaker is tripped, reset it. Make sure you don't over load the breaker. If you have excluded overloads, surges, and short circuits, but the generator still not produces electricity, try using a multimeter to test the circuit breaker. If the circuit breaker malfunctions, replace it with a new one. For safety, it’s recommended that you reach out to an experienced technician to diagnose and fix the problem if you don’t have adequate experience.

5. Defective outlets

Outlets are a part of a diesel generator and you can plug different appliances or extension cords into the generator and access electricity via them. If there is a problem with the wiring or the outlets are damaged, your generator can run normally but no power output is generated.

Solution: Check the condition of outlets and look for burn marks, physical damage, loose wiring, or completely damaged outlets. Replace the outlets if they are damaged.

6. Damaged stator windings or broken excitation winding

All electrical generators require excitation to create electrical energy. The excitation system creates the electromagnetic field in the rotor. The excitation winding that produces the main magnetic field is called the field winding. The stator has the armature winding that has the electrical energy induced. The generator’s stator winding is essential to produce a magnetic field on the generator. If the excitation winding or stator winding is damaged due to overload, an inappropriate working environment or other factors, the generator will not produce the required electric current.

Solution: To find out the condition of excitation winding, you can check the ground insulation of the excitation winding by using a 500V ohmmeter, locate the ground point, and use a multi-meter to find the broken winding and restore it. Additionally, check the condition of the stator windings. If they are simply affected with damp, you can heat the component to dry it out. If there is damage in the form of tears in the stator windings, you need to repair or replace them.

7. Worn brushes

If the alternator of your diesel generator is brushless, you don’t have to worry about worn brushes causing the problem. However, if there are brushes in your generator, damage like cracks, chips, burns and melted spots in the brushes or loose brushes could cause the alternator not outputting electricity. Carbon brushes are electrical contacts which conduct current between stationary and rotating shafts of the alternator. If they are worn out due to friction over time, the generator not producing power issue may also occur.

Solution: You can unscrew the bolts and remove the alternator’s cover, take the brush assembly out and look for conspicuous signs of damage. If there is any damage to the brushes, replace the brushes.

You may also like to read: Differences Between Brushless And Brushless Generators.

8. Damaged diode

Diodes are a small yet essential part of your diesel generator. They are devices placed within an electrical circuit to direct current. A diode permits voltage to flow through it in one direction but blocks it from flowing back the other direction. It's like an anti-backflow valve in plumbing. If there is damage in the diodes, the electricity flow from your generator will be affected.

Solution: Check the condition of the diode and see if anything is damaged or torn. If a damaged diode is found, replace it. Keep in mind that the diode must be installed correctly before you restart the generator.

9. Failed AVR

AVR (Automatic Voltage Regulator) is an electronic device that maintains a constant voltage level to electrical equipment on the same load. It regulates the generator's output voltage and prevents the damage of your electronic devices against frequent electricity fluctuation or the sudden rise and fall of voltage. Sometimes, the AVR may shut down due to damage to components, continuous overload, or a short circuit in the cable connected to the AVR. If the AVR is damaged, there will be low voltage or no voltage. Defective AVR can compromise the safety of your generator, so it’s vital to address it immediately.

Solution: Check the AVR components' condition and ensure none are damaged or torn. If any damage is found, immediately replace the faulty component to ensure a stable generator output voltage.

10. Defective capacitor

The capacitor in your generator regulates power flow, giving clean and reliable energy. A capacitor is required to excite the alternator windings to reduce voltage surges. If the capacitor malfunctions, you won’t get any power from the generator’s output.

Solution: To test the capacitor, you need to remove it from the generator first. Please note that capacitors hold energy even after you turn off the generator, remember to discharge any leftover charge and then use a multimeter or a capacitance meter to take a reading from the capacitor. The reading should be +/- 5uf of the specified rating printed on the side of the capacitor. If not, it should be replaced.

If your diesel generator runs but produces no power, the information above may be helpful. If you can’t diagnose the problem and fix the issue alone due to the lack of experience, reach out to a professional technician to deal with the problem. Don’t hesitate to contact use for any further information or assistance regarding to generator sets. Contact us at dingbo@dieselgeneratortech.com, and we will gladly help you.