Generator

Some common reasons are :
1). Load applied to generator exceeds capacity, typically would cause machine to slow down, drop frequency and voltage typically cause exhaust black stacking and depending on the overload and protection settings could cause machine to stall.

2). AVR Voltage gain set too low to respond to load being applied.

3). If AVR feedback is from generator bus VT and voltage dips too far, all excitation could be lost and would typically result in an u ...

There are Three (3) methods of Powering an AVR (Automatic Voltage Regulation) or AVC (Automatic Voltage Control).

There is the PMG (Permanent Magnet Generator) which others have mentioned and hopefully made it clear that this is an independent AC generator on the same rotating shaft, so its output voltage is proportional to the speed of the Generator rotation. So should be independent of almost anything else.
"With PMG excitation, a permanent magnet generator ...

There's not much to see physically, but electromagnetically there's a lot going on. Once the rotor containing the field winding is up to near synchronous speed, the field is energized creating a variable strength electromagnet. This electromagnet is known as the field and is rotating inside (conceptually) three coils of wire spaced 120 degrees apart. As the magnetic poles pass by the each coil voltages that are 120 degrees apart are induced, this is known as the open circuit voltage of the ge ...

Assume that interconnect two separate systems by closing a circuit breaker on a tie-line. The voltages at both ends of the breaker are independent of each other, as each voltage "belongs" to one system, each system still operating isolated from the other. So, if the voltage difference across the breaker is sufficiently large (and remember that this is a phasor voltage difference, magnitude and phase) when the breaker is closed, that will be equivalent to a fault, a short-circuit in the grid. ...

When more than one generating unit is paralleled to supply a load, none of the units can be truly "isolated". They all work together at the same voltage and frequency constraints.

A utility typically has a large number of paralleled units, providing a large power base. Local facilities may have their own co-generation equipment and/or emergency backup generation.

If the facility generation system operates while the transmission grid is also supplying power, then the faci ...

If you operate a 3600 rpm (60 Hz) synchronous generator at 3000 rpm (50 Hz), the power output will be reduced, simply because the mass of the rotor remains constant and you reduce its rotational speed. Based on the laws of physics, kinetic energy is directly proportional to the mass and the square of the velocity. Conversely, if you operate a 3000 rpm (50 Hz) generator at 3600 rpm (60 Hz) the power output wi ...

The purpose of a generator set is to transform the energy in the fuel used by the prime mover into electrical energy at the generator terminals. Since nothing is perfect, the amount of energy input is ALWAYS greater than the amount of energy output, resulting in an efficiency that is ALWAYS less than 100 percent.

Every fuel has a basic "heat value": this is usually broken down into two cases. The first case uses a LOW value that corresponds to the assumption where the water vapor c ...

Grounding of a generator is required for two reasons. Firstly you will need to gain a reference for your voltage. You may get 380v between phases and 220v to neutral but if the neutral starts to float due to ground surges or induced voltages with in the ground, your voltage to earth may rise above the insulation levels of your system, especially electronic items. This can happen normally but extremes when lightning is around. Secondly, there will be no earth fault path so the first earth faul ...

100% stator ground fault means 100% of the stator winding is protected against ground faults and that includes from the generator terminals all the way to the stator neutral. For 95% stator ground protection means only 95% of the stator winding is protected against ground faults and the remaining 5% which is the neutral part of the generator is not protected against ground faults. Detecting the ground faults at the remaining 5% of the stator winding which is the neutral can be very difficult ...

First - Rotor copper losses: Measure the resistance of the main rotor field winding, recording the temperature at which you made the measurement, then calculate the I^R losses at the operating temperature (Use the temperature coefficient of resistance of copper) and operating current. This is straightforward as long as you can access the main field windings and you have an accurate microhmmeter. If it has slip-rings - which I assume it will - then it is very easy. You can eve ...

As we know that the laminations are insulated from each other to prevent the eddy current circulations between the adjacent laminations. Once lamination staking done, how we are gonna earth the core of any transformer or motor? For a large 11KV motor, I have seen a guide bar welded to the laminations at the core back side & that is grounded to body but that eventually lead to the shorting of insulations at one point.

For motors there is typically a welded bar on the back or the ...

The Power Factor used to declare power ratings on three phase generators is 0.8 (so 100kVA = 80kWs etc.). Unfortunately the difficulty for installers is understanding the effect of power factors within an electrical installation is a changeable situation dependent on equipment within a load. This is something that the installation engineer needs to understand when specifying a generator for a load and in my experience the best method of evaluating what happens in a load is to test it for a le ...

A Neutral Grounding Transformer is NOT a three phase transformer, but a single phase transformer, with the primary (HV) rated voltage equal to the system phase-to-neutral voltage and the secondary (LV) rated voltage either 110V or 240V.

Why is it required? For economic reasons. Let us see how. Supposing you have an 11kV System, whose neutral you want to ground through a resistance. The desired ground fault current, let us say, is 10A. Now, if you want to connect a resistor directl ...

The excitation system requires a very small fraction of the total power being generated. If we could simply increase the excitation (a very small amount of power) and increase the generator's real power output, the world's energy problems would be solved, because we would have a perpetual motion machine.

In the case of a generator connected to a large grid, the generator will inject any desired amount of power into the grid if its prime-mover is fed the desired power (plus a small ...

Distributed generation generally means more than one power source feeding the same loads including sources at multiple locations but it can also mean stand alone or isolated generation at the point of use. Typical for this definition are generator and UPS at mission critical sites such as data centers and laboratories. These can operate in complete isolation, in parallel with the utility grid, in parallel as part of a local grid. Power can also be transferred between the utility grid and loca ...

In static excitation system, at starting we can use DC supply or station supply (field flashing). This system has fast response which is essential requirement now. The basic difference between static and brushless excitation is in static system all components are solid state, no moving parts while in brushless system components (diode rectifier) are rotating. Brushless has a merit that there is no brush and slip ring required as in case of static system which led to maintenance problem.
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Generators can have up to three power output ratings: standby, continuous, and prime. Standby is the least conservative rating, the most power the generator can deliver. The prime is the most conservative. The prime rating of a generator is used where utility power is considered unreliable or not available. Manufacturers have technical papers defining how the ratings are determined and what they mean. Different manufacturers may have slightly different definitions.

Caution, the te ...

In its simplest form an induction generator is simply an induction motor that is rotated above synchronous speed. Unlike a synchronous generator, the field in the rotor is created by drawing large amounts of reactive current from the line.

Synchronization is automatic because line frequency is applied to the stator once the prime mover has accelerated the rotor to near synchronous speed. Remember, unlike a synchronous generator, there is no rotating field on the rotor until it is ...

Let us consider an inverter based distributed generation unit.
There can be many pros and cons
Pros:
1) Can be used in the micro-grid mode when the grid is out or due to an intentional Islanding.
2) Better voltage regulation depending on the controllers applied.
3) Better frequency regulation.
4) Provide grid support
5) Line loss reduction.

But, if we employ static generators at distribution levels, we have to know that the system stabilit ...

We have a 2 by 275kW wind power generators connected to a system with two generators one giving a maximum of 500kW and the other 180kW both having speeds of 750 rpm. All these are to supply a load of about 470kW normal hour and a peak load of about 650kW. The problem is one diesel generator (500kW in this case) is not able to be supply load when interconnected with the wind turbines due high frequency swings (47Hz to 53Hz and the diesel gen-set finally falling off) to reduce this effect we ar ...