Why a generator fails to
produce electricity?
1. The residual
magnetism of the generator core is disappeared or too weak.
The residual magnetism
can be lost naturally when the genset is placed too long or it can also happen
from running a generator with no load for too long. However, for the new genset, the residual magnetism can be lost due to a long distance transportation
vibration. Thus, it will cause the remanence voltage of generator is
disappeared or less than normal remanence voltage value, namely, the remanence
line voltage is less than 10V, the remanence phase voltage is less than 6V.
Because the stator of synchronous generator, rotor, as well as AC exciter
stator, and rotor core are usually folded by adopting 1~1.5mm thick silicon
steel sheet. After excitation vibration, the residual magnetism is easy to
disappear or weaken. When the residual magnetism is lost, the generator will
produce no power at start-up.
2.
Excitation circuit wiring error
The polarity of the
excitation winding is reversed. After electrifying, the magnetic field produced
by the field winding current is counteracted with the residual magnetism, resulting
in the disappearance of the remanence. In addition, when measuring the DC
resistance of the excitation winding or testing the automatic voltage regulator
AVR, without paying attention to the polarity, which will also cause the core
remanence to disappear.
3.
Excitation circuit is blocked
In the generator
excitation circuit, the electrical contact is bad or the wiring head of each
electrical component is loose, the lead wire is broken, causing the circuit to
be interrupted, and the generator excitation winding has no excitation current.
4.
Circuit for DC side of rotary rectifier is interrupted
Due to the interruption
of circuit for DC side of rotary rectifier, therefore, after the AC exciter is
rectified by the rotary rectifier, the excitation current supplied to the
excitation winding can not be sent into the excitation winding, resulting in AC
synchronous generator can not generate electricity.
5.
AC exciter fault, no output voltage
The generator can’t
produce electricity due to AC exciter failure, so that the excitation winding
of the AC synchronous generator has no excitation current.
6. Generator excitation
winding is broken or grounded, resulting in the generator has no excitation
current or the excitation current is minimal.
How
to solve it?
1.
When the residual magnetism of the generator core disappears, magnetizing
treatment shall be carried out.
The magnetizing method：For the self-excited
generator, usually using extra battery or dry battery, using its positive and
negative poles to supply electricity for a short time towards the leading-out
terminal of the excitation winding. However, be sure to recognize the polarity
of DC power supply and excitation winding clearly, namely, the positive pole of
the DC power supply is connected to the positive pole of the excitation
winding, and the negative pole of the DC power supply is connected to the negative
pole of the excitation winding. If the control panel of diesel generator set is
equipped with magnetizing circuit, the toggle switch should be turned to
“magnetizing” position, which can magnetize the AC exciter.
2.
Excitation circuit wiring error, correct it after searching.
3. Use multi-meter ohm
block to find the excitation winding broken line and connect it. For the
failure caused by poor contact, polish the surface oxide layer with find sand
cloth, the loose connection bolt and nut shall be firm.
4. Ground and broken
line fault of excitation winding. Use 500V ohmmeter to check the ground
insulation of the excitation winding, find out the ground point, use
multi-meter to find out the broken line and restore it.
Hope the above methods
can help your restore your generator output power. If it still fails. you need
to replace the automatic voltage regulator as it may be damaged.
Comments
Post a Comment