5 reasons and repairing methods for the failure of diesel generators without generating electricity

1. Generator magnetic pole failure

cause of issue:

  The newly installed unit is subject to long-distance transportation or the generator is placed for too long, the residual magnetism of the generator core disappears or the residual magnetism is weak, causing the generator residual magnetization voltage to disappear or be lower than the normal residual magnetism voltage value, that is, the residual magnetism line voltage is less than 10V , The residual magnetic phase voltage is less than 6V.

  Since the stator and rotor of the synchronous generator and the stator and rotor cores of the AC exciter are usually punched and laminated with silicon steel sheets with a thickness of 1 to 1.5 mm, they will be vibrated, and the remanence will easily disappear or weaken, which directly leads to the occurrence of No electricity can lead to no power generation.

Troubleshooting method:

  To magnetize the generator, you can connect a 12V battery.Find the voltage regulator board of the generator and connect the voltage regulator board circuit to the battery circuit. There are two excitation wires F+ and F- on the voltage regulator board. Next, do not connect directly to the pressure regulator board to avoid damage to the pressure regulator board, and start the generator set after checking it is correct.

1) Open here and find the pressure regulator board

2), the following picture is the pressure regulator board seen after opening

Take AS440 as an example, 7 and 8 are live wires, F1 is the positive electrode, and F2 is the negative electrode.

3) "F+(F1)" is connected to the positive electrode of the battery, and "F-(F2)" is connected to the negative electrode of the battery.After completion, start the generator set.If the generator still does not generate electricity after following the above steps, find other reasons.

Check and correct against the wiring diagram

2. The rectifier bridge is damaged

cause of issue:

  The sudden turn-off of the generator load causes a sudden rise in voltage, which makes the rectifier tube breakdown and damage.

Troubleshooting method:

  Replace the rectifier bridge, use simple daily tools to remove and replace.

The rectifier bridge is located inside the generator

The location of the rectifier bridge inside the generator

(The rectifier bridge module will be different according to the model of the generator set)

The picture above shows the rectifier bridge module 1

The picture above shows the brushless rectifier bridge module 2

3. The excitation circuit of the generator is disconnected or has poor contact.

cause of issue:

  When the generator set is overhauled, the polarity of the field winding is accidentally reversed. After the power is turned on, the magnetic field generated by the field winding current is opposite to the remanence direction and cancels out, causing the remanence to disappear.

  In addition, during maintenance, measuring the DC resistance of the excitation winding or experimenting with the automatic voltage regulator AVR when the excitation winding is the same as the DC current, without paying attention to its polarity, it will also cause the residual magnetization of the iron core to disappear.

Troubleshooting method:

  This type of situation is caused by operating errors at the factory, and you can contact the manufacturer for repair.

Check the current and voltage changes of the instrument panel at startup. Generally, the armature current of the motor increases instantly, and the armature voltage drops to about 10V.

4. Contact failure of brush and slip ring

cause of issue:

  The generator brush is in poor contact with the slip ring, or the brush pressure is insufficient.

Troubleshooting method:

  Remove sharp dirt on the contact surface, grind the brush, adjust the pressure of the brush, and make the brush and the slip ring closely contact.

The slip ring is inside the generator set

Slip ring

Schematic diagram of slip ring after cleaning

5. Excitation winding failure

cause of issue:

  The wiring of the excitation winding is wrong, and the polarity is reversed.

Troubleshooting method:

  Correct the wiring and magnetize according to the correct polarity.

Open here to find the field winding wire

Coil F1 is connected to the positive pole, and F2 is connected to the negative pole.