Definition: The system which is used for providing the necessary field current to the rotor winding of the synchronous machine, such type of system is called an excitation system. In other words, excitation system is defined as the system which is used for the production of the flux by passing current in the field winding. The main requirement of an excitation system is reliability under all conditions of service, a simplicity of control, ease of maintenance, stability and fast transient response.
Brushless Excitation System of Turbo Generator
The brushless excitation system works in the absence of commutator, slip rings and brushes. Instead of these components we are using Permanent Magnet Exciter and three phase main Exciter with silicon diode rectifier the system has generated. With this system we can avoid dust particles which cause a great maintenance cost. The complete structure of this excitation system is explained clearly in this review. Drawback of this system is presence of considerable exciter time constant which affects the rate of change of voltage.
Auxiliary Coil Excitation (PMG-I)
How common are generators(alternators) that don’t have permanent magnet generators? I haven’t seen any personally but was browsing the CFRs and it doesn’t specifically say for main generators. Although 111.12-3 does mention something about e-gen excitation.
In this case a setting of 5% of normal of full load current is recommended. There is a normally closed contact attached with the undercurrent relay. This normally closed contact remains open as the relay coil is energized by shunted excitation current during normal operation of the excitation system. As soon as there is any failure of excitation system, the relay coil becomes de-energized and the normally closed contact closes the supply across the coil of timing relay T1.
Important Points to Consider While Carrying out Alternator Maintenance of Ship’s Generator
A ship cannot remain “Live” without a Generator – the lifeline and power production plant of the vessel. A generator on ship is a combination of two separate systems – an alternator and a prime mover whose capacity depends upon the number of machinery or power consuming items fitted on the ship.
OPERATION OF A GENERATOR
Rotating equipment is so common, yet so misunderstood, that even highly experienced electricians and engineers are often plagued with questions about their operation. This article will answer seven of the most commonly asked questions. The explanations are brief and practical due to space limitations; however, they will enable you to have a better understanding of this equipment.
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Power Systems and AC Alternators
Since certain electrical systems operate only on AC, many aircraft employ a completely AC electrical system, as well as a DC system. The typical AC system would include an AC alternator (generator), a regulating system for that alternator, AC power distribution busses, and related fuses and wiring. Note that when referring to AC systems, the terms “alternator” and “generator” are often used interchangeably. This chapter uses the term “AC alternator.”