Skip to main content

Archive

Show more

How To Deal With Sudden Short Circuit Faults of 200kw Diesel Generator Set

When we use diesel generator set, maybe there is a sudden short circuit problem, do you know how to deal with this problem? Today Starlight manufacturer will shares with you.

Because magnetic circuit and magnetic resistance for direct axis of synchronous generator is different from that of variable axis, the stator and rotor are in relative motion, so the mutual inductance coefficient and self-inductance coefficient of stator and rotor are not constant. It is difficult to analyze and solve by using differential equations, based on the principle of flux conservation in superconducting closed loop, explain from the physical concept, and derives the short circuit current in each winding when sudden short circuit occurs.

Yuchai diesel generator

Characteristics of sudden short circuit for diesel generators
1.In the case of steady-state short-circuit, the steady-state short-circuit current is not large because of the large synchronous reactance, while in the case of sudden short-circuit, the sudden short-circuit current is large because the super-transient reactance limiting its current is very small and contains DC component. The peak value of the sudden short-circuit current can reach more than ten times of the rated current.
2.With the emergence of this impulse current, the winding of the electric motor will be affected by a great impulse electromagnetic force, which may cause the winding to be deformed or even the insulation of the winding to be damaged.
3.In the process of sudden short-circuit, the electric motor is affected by strong short-circuit torque, which can cause vibration.
4.Overvoltage occurs in stator and rotor windings of motors.

Characteristics of physical phenomena in generators during sudden short circuit
1.When in steady-state short circuit, the armature current is constant, and the corresponding armature magnetic potential is a constant amplitude rotating magnetic field rotating at synchronous speed, therefore, it will not induce electromotive force and generate current in the rotor winding. From the current relationship, it is equivalent to the open circuit state of transformer.
2.When short circuit occurs suddenly, the magnitude of armature current varies, and the corresponding magnitude of armature magnetic field varies. Therefore, the transformer between stator and rotor can induce potential and current in the rotor winding, and then affect the change of current in the stator winding. From the point of view of electromagnetic relationship, it is equivalent to the sudden short-circuit state of transformer.

What is the harm of sudden short circuit of diesel generator set?
1.When the diesel generator is short-circuit suddenly, the end of the generator winding will be greatly impacted by electrodynamic force, which may cause the end of the coil to be deformed or even damage the insulation.
2.Overvoltage in stator and rotor windings of diesel generators is harmful to generator insulation. Powerful impulse current in stator winding, combined with overvoltage, may lead to breakdown of weak insulation links.
3.Diesel generators may produce violent vibration, which may cause strong and destructive mechanical stress on some structural components.
4.Sudden short circuit on the secondary side will damage the transformer.

When the secondary side of transformer is short-circuited suddenly, a huge short-circuited current will be generated in the winding, whose value can reach 20-30 times of the rated current. The harm to transformer at so large current is as follows:
1.Under the action of huge short circuit current, huge electromagnetic force will be produced in the winding, whose value can reach 400-900 times of rated electromagnetic force, which will destroy the mechanical strength of the winding.
2.Huge short-circuit current will heat the winding, produce high temperature, and may burn the winding.

Therefore, the transformer must have reliable short circuit protection device, so that the transformer can operate safely and normally.

If the short-circuit phenomenon occurs in diesel generating sets, corresponding measures can be taken.
1.After checking the fuse, it was found that the fuse had been burned out. The phenomenon of burning of the components in the control box was observed. During the checking, it was found that the two-stage tube with limited current had been burned out.
2.Six rectifier diodes were measured with a multimeter, and no abnormality was found from the test results.
3.After replacing the current limiting diode and fuse, start up the diesel engine, when the rated speed is reached, the generator is not generate electricity.
All above faults indicates that the fault may be that the residual magnetic voltage inside the exciter is too low (in the process of normal power generation, a sudden short circuit of the electrical equipment and a large fireball will result in the disappearance of the residual magnetic voltage inside the exciter).
4.After charging the exciter with a battery, start the diesel engine to the rated speed, and the generator starts to generate electricity and meets the required requirements.

Cummins generator

Sudden short circuit is a serious problems for diesel generator sets, we need to deal with it in time, so that can make diesel genset service life longer. Starlight power generator manufacturer will provide support for you all the time if you have any generator question or need to purchase diesel generators.

Comments

Popular posts from this blog

New Yuchai engine YC6K600-D30 power for diesel generator 50Hz

Silent Cummins 640kw Diesel Generating Sets

Technical data of 800KVA AC diesel generator set The DG Set is skid mounted, directly coupled with Cummins water cooled engine with built in shock absorber for anti vibration. The alternator is Stamford brand with brushless and self excited, with control panel and protection system complete set. Prime power: 640KW/800KVA Standby power:704KW/880KVA Rated voltage: 230/400V Rated current: 1152A Speed/frequency:1500rpm/50Hz ( or 1800rpm/60Hz) Power factory:0.8lag Size: open type genset: 4.2 x1.82x2.25m, silent genset: 6.5 x2.6 x2.78m Net wight: open type genset: 7800kg,   silent genset : 12000kg Technical Data of Diesel Engine Diesel engine brand/model: Chongqing Cummins/ KTA38-G2B( full new) Prime/standby power: 790KW/920KW 4 Stroke Cycle , 60° Vee , 12 Cylinder, Turbocharged &Aftercooled, 1500rpm, 50Hz, bore/stroke: 159/159mm. The Cummins diesel engine is equipped with electronic type governor, over speed shutdown devices to protect against runaway when electronic governor or con...

Guides to Clean VOLVO Diesel Generator Cooling System

VOLVO Engine Cooling System Volvo engine's internal cooling system makes sure the engine works at the right temperature. It is a closed system that must always be filled with a mixture of concentrated coolant and water in order to protect the engine against internal corrosion, cavitation and bursting due to freezing. Coolant of a suitable chemical composition must be used all year round. This also applies in areas where there is never any risk of freezing, to provide the engine of  diesel generator set   with full corrosion protection. The use of anti-corrosion agents alone is not permitted in Volvo Penta engines. Never use water alone as a substitute for coolant. The corrosion protection additives become less effective over time, which means that the coolant must be changed at regular intervals; refer to Maintenance Schedule. The cooling system must be flushed whenever the coolant is changed; Volvo Penta coolants have been prepared to work best ...