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How To Deal With Unstable Output Voltage Of Synchronous Generator

Jul. 11, 2022

Synchronous generator, that is, an alternator whose rotor speed is the same as that of the stator's rotating magnetic field, is one of the most commonly used alternators. In the modern power industry, it is widely used in hydropower, thermal power, nuclear power and diesel power generation, but the output process will lead to voltage instability, then Jiangsu Starlight Electricity Equipments Co.,Ltd. will explain to you in detail.


After the generator set starts and runs, the voltage (current and frequency) of the generator fluctuates when the generator is no-load or when the load is running. For this we get the following failure reasons:


1. There is a fault in the internal combustion engine speed control device, which makes the fuel supply of the internal combustion engine fluctuate, causing the unit speed to be unstable and causing fluctuations in the output voltage and frequency of the generator.


2. In the excitation circuit, the voltage adjustment setting potentiometer is in poor contact or the wiring is loose, and the wiring of the rotating rectifier is loose, which makes the excitation current fluctuate and causes the generator output voltage to be unstable.


3. The insulation of the excitation winding is damaged to the ground. When the motor is running, the winding is grounded from time to time, causing the voltage to fluctuate.


4. There is a fault in the excitation system circuit of the automatic voltage regulator, which makes the voltage regulator control the excitation current unstable.


5. It may be caused by excessive vibration during the operation of the diesel generator set. Check immediately whether the shock absorber of the generator set is damaged or the generator set is unbalanced.


6. The voltmeter is invalid and shows unstable voltage. Replace with a new voltmeter.


diesel generator set

The solution to the unstable output voltage of the generator set:


1. If the rotational speed is unstable, check whether the main and auxiliary springs of the governor of the internal combustion engine are deformed, whether the pin hole of the flyweight roller and the seat frame are worn and loose, whether the oil pump gear and the rack are properly matched, and whether the distance between the flyweights opening and closing is not consistent, whether the governor housing hole and the rear cover of the oil pump are loose, and whether the camshaft travel clearance is too large. Find out the cause of the failure through inspection, replace the worn parts, and adjust the parts with improper clearance to make the governor return to normal.


2. If the excitation current is unstable, causing the generator voltage and current to be unstable, stop the machine to check whether the generator excitation circuit adjustment potentiometer and the rotating rectifier are in good condition, and repair after confirmation.


3. Use a 500V megger to find out whether the insulation of the AC synchronous generator or the excitation winding of the AC exciter is damaged to the ground and whether the grounding is good, and repair it.


4. For the fault of the excitation circuit AVR circuit, identify the fault point of the circuit and replace the damaged components.


5. Check the shock absorber equipment of the generator set, adjust or replace the engine fuel system parts to make the speed stable.


Jiangsu Starlight Electricity Equipments Co.,Ltd. is one of the earliest manufacturers of generators and diesel generator sets in China. The company was established in 1974 and the company occupies an area. With an area of 86,000 square meters and a building area of 45,000 square meters, it has 64 sales and service departments across the country to provide users with one-stop service of design, supply, debugging and maintenance at any time. Welcome customers to come to consult and visit. Looking forward to your inquiry, please send email to us for details sales@dieselgeneratortech.com.

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