Skip to main content

Archive

Show more

What is phenomenon when the rotating rectifier failure of generator?

After using for a certain period of time, the rotating rectifier of diesel generator set maybe break down, which often leads to the failure of normal operation of the whole generator set.

What is the function of rotating rectifier of diesel generator set?
Rotating rectifier is a device which rotates coaxially with AC exciter. Its main function is to convert the three-phase AC excitation current output by the armature of the AC exciter into the DC current through the diode on the rectifier, supply the rotor winding as the power supply for the excitation current. It is because of the application of rotating rectifier that the AC synchronous generator gets rid of the binding of brush, no longer has the trouble of frequent maintenance and replacement of parts, and also makes the application of the AC synchronous generator more extensive.

silent generators

Some rotating rectifiers of AC synchronous generators are installed on the outside of the AC exciter and fixed on the shaft with screws for easy installation and maintenance. Some rotating rectifiers of generators are installed on the inner side of the rear end cover and directly fixed on the bolts protruding from the armature core of the exciter, making the structure more compact. There are two kinds of rotating rectifier circuits: three-phase half wave and three-phase bridge rectifier. If the three-phase bridge rectifier circuit is adopted, in order to facilitate installation, reduce the connection line between the rectifier elements and improve the reliability of the generator operation, the rectifier diodes are of two tube types, positive and negative poles are exactly opposite, which is convenient for wiring.

What is phenomenon when the rotating rectifier failure?
Rotating rectifier is usually composed of silicon rectifier elements. If one or several rotating silicon elements in the circuit are damaged, the damaged silicon element will lose one-way conductivity (both positive and negative conduction), resulting in a short circuit of the circuit. Once the rotating silicon element is short circuited, the generator has no output voltage when the unit is running. If the faults are not found and removed in time, the armature winding of the AC exciter will be burnt out and the generator will be forced to stop.

What cause the rotating rectifier failure?
1.The silicon rectifier diode of rotating rectifier is damaged due to over-voltage or over-current.
2.When the silicon rectifier element of the rotating rectifier is installed, the torsional moment is too large, which leads to the deformation of the tube shell and the damage of the internal silicon wafer.
3.The load power factor is too low, which causes the excitation current to exceed the rated current of silicon rectifying element for a long time and damages it.

How to deal with the problems?
1.Rotating silicon elements shall be provided according to the current level specified in the drawing. If there is no drawing data at hand, the standard silicon element can be relied on according to the excitation current value of the main generator. At present, the common specifications of rotating rectifiers produced in China are 16A, 25A, 40A, 70A and 200A.
2.The voltage level of the rotating silicon element shall be reasonably selected, and the reverse peak voltage urn of the rotating silicon element shall be 10-15 times of the excitation voltage UIN.

3.Tighten the nut of rotating silicon element with proper torque, and tighten the nut with constant torque wrench. The torque value of tightening the rotating silicon element nut shall be in accordance with the provisions shown in the manual which provided by the supplier.
4.Take over-voltage protection measures. Overvoltage protection is usually equipped with varistor or resistance capacitance absorption circuit on DC side of rotating rectifier.

Hope the article is helpful to you. Starlight Power manufacturer also supplies diesel generator set, cover Cummins, Volvo, Perkins, Deutz, Yuchai, Shangchai, Ricardo, Weichai, MTU, Doosan etc. Power range 20kw-3000kw. Welcome to contact us by email sales@dieselgeneratortech.com, we will work with you. 

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 ...