A sudden load current flow on a generator certainly causes a great impact or change in its output voltage. An internal voltage drop in the generator winding is the prime cause of it and this effect is called voltage dip. Here, comes an AVR (Automatic Voltage Regulator) which can regulate or correct such voltage change. An AVR is a cardinal part of a device which regulates voltage automatically. It takes a fluctuating voltage level and converts it into a constant voltage level.
Functions of AVR
The prime functions of an AVR are,
• It stabilizes the output voltage of the generator
• In parallel operation, an AVR divides the reactive load between the generators.
• Under fault conditions, an AVR maintains the excitation of the system.
How does an automatic voltage regulator work?
Based on the principle of detection of errors, an automatic voltage regulator works. Generally, the output voltage of an AC generator obtained through a potential transformer. After that, it is rectified, filtered, and finally compared with a reference. The difference between the actual voltage and the reference voltage is called an error voltage. An amplifier generally amplified this error voltage and then it is supplied to the main exciter.
When a sudden change occurs in load in the alternator, then there must be a change in the exciting system in order to provide the same voltage under the new condition. With the help of an automatic voltage regulator, this can be done easily. The automatic voltage regulator operates in the exciter and changes the exciter output voltage as well as the field current. But an AVR doesn’t give a quick response during the fluctuation of voltage. To get a quick response, the quick-acting voltage regulators (based on the overshooting the mark principle) are used.
AVR maintains the generator O/P voltage + or – 2.5% of its set value over the load range. A manual or hand trimmer regulator is trimmed on a generator control panel so that the voltage level can be set perfectly. The controlling circuit for a modern AVR consists of transformers, rectifiers, Zener diode, transistors and thyristors. All these components are mounted in one or more circuit either at the switchboard or at generator panel.
Ship automation is an eminent company that repairs and supply marine automation and electrical spares at a lucrative price to the clients. The company has profound experience in ship automation system, marine automation system, and marine control system. The company deals with various automatic voltage regulators and other products which will make your business more hassle-free and easier.
tcnloop.wordpress.com 