AC Power Source

The earliest proponent of alternating current (AC), Thomas Edison pushed direct current. If I remember my history right, 60Hz was a frequency that would produce no visible lamp flicker. There were (and still remain) 25Hz, 50Hz, 133Hz, & 400Hz power systems.

The initial investment in one frequency, early power generators (hydro i.e. low frequency) would have made sudden changes to be very costly. But some of the reasons are to do with lig ...

Electrical machines designed for 50Hz can usually work safely in 60Hz power supply, but not applicable to 60Hz machines to be run in 50Hz power supply. This is because impedance of 50Hz machines increases if operate in 60Hz supply which also lowers the running ampere, while if 60Hz machine run in 50Hz power system will experience increase in running ampere & overheating that will result to reduced life expectancy of the equipment. In motors coupled to water pumps or compressors increase o ...

Current variations in the power supply causes severe problems in the electrical devices i.e if it increases or decreases in both cases it causes overheating which melts the conductors. High current is said when the current is above the ratings of any electrical devices, this rises the temperature of the transformer similarly when the current is below the min. rated value of the transformer but the load remains constant because of which it draws heavy amount of current to meet the load current ...

Why not a 59 Hz? I prefer a prime number. If I were J.P. Morgan, I'd like to make Tesla have such a cool frequency. Or US yields to 55 Hz, and Germany get a 5 Hz bonus.
In the true world, a wide range of frequency for electrical machine could work economically, but in a real world, people make the standard, and 60 Hz simplified, e.g. the calculation. I guess Nikola Tesla had more common sense than I have. However, if I were born 100 years earlier ...

Q: Has anyone got experience in using a 50 Hz Alternator of about 20 MW, in a 60 Hz system country? What are the changes required in the alternator? Is it economical to carry out this change or one has to go in for a new alternator for 60 Hz only. There are lots of commercial requests for such usages of 50 Hz machine in 60 Hz locations and vice versa.

A: You can use a 50 Hz alternator in 60 Hz power system without changing the internals. The concern though, is the operational speed ...

I have used three different Methods depending on the details of a specific project plus I do not use the Method 4.

Method 1. Secondary pre-charge
This is normally the most economical Method. It uses a small pre-charge transformer to apply a voltage to the transformer's secondary and I normally use 90% of the rated transformer's secondary voltage. The required current is approximately the transformer's magnetizing current. A typical value is 0.5% of the rated w ...

There is no standard for this voltage!! In 2002 the IEC put forward the new voltage standard and change was as the 220v was charge to 230v, 380v was charge to 400v and 660v was charge to 690v all with the tolerance of +/- 10% the frequency is always based on 50Hz. You will find that each voltage has the square root of 3 as a multiplication (1.73). The reason is star Connection at 400v give you delta in 690v!

For achieving the correct 60Hz v ...

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 will ...

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 ...

50Hz vs 60Hz in operating speed

The primary difference between 50 Hz (Hertz) and 60 Hz (Hertz) is, well, 60Hz is 20% higher in frequency. For a generator or induction motor pump (in simple terms) it means 1500/3000 RPM or 1800/3600 RPM (for 60Hz). Lower the frequency will be the iron losses and eddy current losses. Lower the frequency, speed of induction moto ...

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 ...

A standard protection philosophy for large generators is to use two protections with independent principles. Injection method protects 100% stator windings without the need of a 95% relay. It works on its own. One group would protect 90% of the stator winding and another group would protect 100% of the stator winding.

A signal generator injects voltage pulses in the windings of the machine at a frequency different from the rate frequency of the system or any harmonic (typically 10 ...

The changing gain issue certainly squares with some of the problems that I see in the time domain simulation. The stability problem is at its worst at the peak of the AC cycle.

I re-ran the time domain simulation last night and came to some interesting empirical conclusions, regarding stability:

1) The rail voltage needs to be 1.5 times the maximum peak AC output voltage. This keeps you away from running the inverter near 100% duty cycle, where many of the chaotic stab ...

The floating neutral in Power distribution can play havoc. The household appliance/gadgets operate at 230-250 volts, which is the line voltage (Phase to Neutral voltage) of a distribution system. A 3 phase Distribution Transformer of say 11kV/0.433 k V,.Dy11, having winding of Delta in Pry and Star in secondary side (generally Dy11 group). Its secondary phase to phase voltage will be 433 V and Phase -Neutral voltage will be 433/√3 = 250 V.
Due to floating neutral, the phase to pha ...

We are known that there are two transformer circuits in electrical distribution. One are power circuit & second are control circuit. The transformer who connected HT bus bar and supply feeds to HT motor is all most Power transformer because it is connected with power circuit. Other low voltage transformer is mostly connected in control circuits. It's distributed power (voltage or current) to any machine so it called distribution transfor ...

All electrical loads (including power transmission cabling) are some combination of resistive (R), inductive (L), and capacitive (C) circuits. All AC voltage and current waveforms have some angle between them; the cosine of that angle is called "power factor" and is typically expressed as a per unit (or sometimes percentage) value.

Capacitate load in three phase is used to raise the power factor, since the circuit current in capacitive circuit leads the supply voltage. The measure ...

On a centrifugal pump, the head at the discharge end should be 44% higher than if it were run at 50Hz, so the shaft torque would also be 44% higher, no? A throttling valve will restrict flow and reduce the load, but at the designed flow rate under 50Hz operation, the motor will still be operating 20% faster than it would at 50Hz. I'll take your word that this is acceptable.

What I would do would be to discuss the pump application with the manufacturer and see if it was possible to ...

The frequency output of the Permanent Magnet Generator is related to the pole count of the exciter - compared to the motor it is feeding.

If the motor line frequency is 50 Hz, then the exciter has 3x the pole count of the synchronous machine (i.e. 2-pole synch with 6-pole exciter design, or 4-pole synch and 12-pole exciter, etc.)

If the motor line frequency is 60 Hz, the exciter has 2.5x the pole count of the synchronous machine (i.e. ...

The core saturation is a physical phenomenon. It happens when the coupled magnetic flux is so intense that all magnetic domains on a ferromagnetic material are already aligned and thus does not respond to any further increase in the flux. The implications on the current transformer secondary current may be diverse. Having a saturated core does not mean the current on the current transformer secondary will be high or even constant as the flux increases.

Once saturated, the inductan ...

Using a line choke (inductor) that was designed for 50 Hertz on a 60 Hertz power system would appear to be an error/omission on the part of the designer/engineer but it can work satisfactorily if it is applied correctly and operated within its ratings: volts/hertz, voltage, current, harmonics, volt-second balance, temperature, etc.

The high levels of noise can be due to many factors. The most likely are harmonic currents produced by the dr ...