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Why My Cummins Diesel Generator Does Not Generate Electricity

Aug. 12, 2018

Cummins generator set will occasionally encounter generator failure in the process of use that Cummins generator set is not generating electricity. What is the cause of it? And what to do about it? In fact, there are a lot of reasons that Cummins generator set is not generating electricity. The following is compiled by Jiangsu Starlight Electricity Equipment Co.,Ltd to summarize the main reasons for generator not to generate electricity and the treatment methods.


Why My Cummins Diesel Generator Does Not Generate Electricity.jpg


1. Wrong connection of generator set. Processing: check and correct by wiring diagram.

2. Generator speed is too low. Processing: measuring speed and keeping it at rated value.

3. The connection between the stator winding and the generator distribution equipment has sludge or oxide, the connection screw is loose, the connection wire is broken, and the stator winding is broken. Handling: use a multimeter or lamp test method to find out where the wire is broken. Check the connection and contact of each connection screw.

4. Excitation circuit broken or bad contact. Processing: use multimeter to identify broken wire and reweld the broken wire to bind insulation.

5. Rectifying tube (including rectifier diode, thyristor) is damaged. Treatment: replace damaged parts.

6. Brush contact with slip ring bad or brush pressure is not enough. Treatment: clean the surface of the slider ring, polish the brush, make it match with the surface of the slider ring, increase the brush pressure.

7. Brush grip rusts, brush can not slide up and down. Treatment: wipe the inner surface with a cloth brush, if damaged, should be replaced.

8. Cummins generator exciter brush position is incorrect, brush damage or spring pressure is not enough. Handling: adjust the brush to the correct position, replace the brush, adjust the spring pressure.

9. The prime mover rotates in the wrong direction. Processing: changes the rotation direction of the prime mover.

10. Cummins generator exciter winding wiring error, polarity reverse. Handling: correct winding connection and recharge magnetic with dry battery and battery according to its polarity.



Why generators do not generate electricity


1. Fault phenomenon


When the generator set speed reaches the rated speed, the AC exciter stator excitation circuit switch is closed and the voltage regulator is adjusted to the maximum value when the generator speed reaches the rated speed.


2. failure cause

The generator core remanence disappears or is too weak, the newly installed unit is disturbed by long-distance transportation or the generator is placed for too long, the generator core remanence disappears or the remanence inductance is weak, which results in the generator remanence voltage vanishing or less than the normal remanence voltage value. That is, the remanence voltage is less than 10 V, and the remanent phase voltage is less than 6 V. Because of the stator, rotor and AC exciter stator of synchronous generator, the core of rotor is usually made of 1mm-thick silicon steel sheet, which is subjected to vibration after excitation, and the remanence magnetic field is easy to disappear or weaken.



When the generator is overhauled, the polarity of the excitation winding is connected by accident, and the magnetic field produced by the current of the excitation winding is counteracted by the direction of remanence, which results in the disappearance of the remanent magnetic field. In addition, when measuring the DC resistance of the excitation winding or testing the DC current of the excitation winding by AVR, the polarity of the excitation winding is not noticed, which will result in the disappearance of the core remanence.


The circuit of excitation circuit is impassable, the electrical contact in generator excitation circuit is bad, the connection of each electric element is loosely removed, the lead is broken, the circuit is interrupted, and the excitation winding of alternator is not excited.


The DC side circuit of the rotary rectifier is interrupted. Because the DC side circuit of the rotary rectifier is interrupted, the excitation current provided to the excitation winding can not be fed into the excitation winding after the exciter is rectified by the rotary rectifier, resulting in the AC synchronous generator being unable to generate electricity.


Ac exciter fault no output voltage. The fault of AC exciter can not generate voltage, which makes the excitation winding of AC synchronous generator without excitation current.


Generator excitation winding is broken or grounded, resulting in minimal excitation current or excitation current.



3. processing method


When the residual magnetism of generator core disappears, the magnetizing treatment should be carried out. The magnetization method is as follows: the self-excited generator is usually connected to the end of the excitation winding by using its positive and negative poles in a short time, but the polarity of the DC power supply and the excitation winding must be clearly recognized. The positive pole of the DC power supply is connected with the positive pole of the excitation winding, and the negative pole of the DC power supply is connected with the negative pole of the excitation winding. If a magnetizing circuit is provided on the control panel of a diesel generator set, the button switch should be switched to the "magnetizing" position, which can be magnetized to the AC exciter. For the third harmonic excitation generator, when the no-load excitation voltage can not be established, the DC power can be used to magnetize.



Excitation circuit wiring error, after looking up to correct.


The multimeter ohmic block is used to find the broken line of the excitation circuit and to connect it. Where the fault is not in good contact, the oxide layer on the surface is polished with fine sand cloth, and the loose connection bolt nut should be strong.


The grounding and breakage faults of excitation windings can be checked by 500V megabytes to check the ground insulation of the windings, to find out the place of connection, and to fix the broken wires by multimeter.


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