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When saying remote controlled, then some control gadgetry and circuitry gets involved in the business; meaning that it is not simply a circuit breaker. There is an automatic off/on gadgetry involved in it and the additional wiring and circuitry to be done depending from where you need to control it; right below the pole, at the nearest substation or at the remote Load Center.

Bottom line, you are not comparing an apple to an apple in this case.

A pole mounted Recloser ...

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 ...

Switching frequency selection, employing the right gate driver circuitry with appropriate gate resistance value, noise immunity at the gate drive circuit, parasitic elements and their effects, the high frequency switching noise, appropriate gate drive voltages are all the vital factors to be considered while designing the IGBT Full bridge inverters.

The real field performance of the Full Bridge IGBT Inverter is completely dominated by those issues only, for any application.
...

The variable frequency drive (VFD) has the capacity of 11kW, it's a rotogravure printing machine which is used in packaging industry (plastic web films). The data is collected from the VFD display when the motor was running:

The set speed or speed command given was 100 m/min via HMI (Touchscreen LCD)
Frequency Reference: 48.83 Hz
Output Frequency: -50.10 Hz to -50.82 Hz (Not stable, fluc ...

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 ...

The vast majority of variable frequency drives (VFDs) are the "voltage-source inverter" (VSI) type with a diode front-end. These non-regenerative VSI-type VFDs, do not contribute to upstream fault current as the input diodes block any current that might flow from the dc bus to the mains.

For regenerative VSI VFDs, the actual front-end regenerative circuit can be either transistors (IGBT, etc.) or thyristors. The VFD controls will respond very quickly. The controls will sense eithe ...

Cable selection is not just dependent on the load. There is also a requirement that the cable withstand all the short circuit current that the source might be able to deliver. It has to carry this large current, without significant damage, for the duration that it takes for the circuit protection to operate. This method applies to cables rated up to 600 volts phase to neutral (or 1kV phase to phase) and has some basis in IEC 60287.

The first step is to determine the maximum prospe ...

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 transfo ...

Skin effect is, indeed, not a problem at DC.

However, at AC frequencies up to about 1 KHz, the impedance of wire decreases, it doesn't increase. The governing equation for Z_0 for AC below 1KHz is sqrt(R/(j2(pi)fc)). Above about 100 KHz it becomes sqrt(L/C), and R doesn't even figure into the equation. From about 1 KHz to 100 KHz, skin effect starts to take effect.

This is because skin effect, the confining of electrons to an area near the surface of a solid circular-c ...

A relay operates like an electromagnet. A relay is a switch; which can make contact between two points. Here, there are three such points; COM (common), NO (normally open) and NC (normally closed). The COM will be connected to NC in normal state. The input to the relay, excites an electromagnet (relay coil) so that the normal connection (i. e. , between 'com' and 'NC' terminals) gets switched, so now the connection is between com and NO.

The relay is just a switch. It just do the ...

Most manufacturers have separate product families for "servo drives" and "variable frequency drive" or "inverter". However, if we take one of the many VFDs that support PM motors with sensor and a PM servo drive, the control, is the same up to the speed loop. Both servo and VFD (except for DTC) need an inner vector current control loop, which means torque control, and a speed control regulator. They also need a self-tuning p ...

When we say control the first thing comes in theory or practical is that it should have a low value of noise which is apparently achieved by DC.
- 24V is far safer limit than compared to higher values 115V AC.
- 24V DC is more resistant to control circuit drop out caused by high inrush using contactors used for starting motors or any capacitive load as well.
- Modern day electronics can now be operated at lesser voltage, Optos, relays, improving efficiency of the system and l ...

I have used variable frequency drives (VFDs) from a number of manufacturers over the years (ABB, Gozuk, Control Techniques, Emerson, to name a few), and I have not had specific failures with any of them. What I did do:

1) Spent a lot of time up front to size the VFD properly for the application.

2) Spent time up front to research the VFD product specified to be used for the application - in ...

In my opinion there are three different kind of possible failures for a solar inverter:

1) Infant mortality due to poor assembly work or components intrinsic defects. In this case the solar inverter lasts for few hours or days before to fail

2) Wear out of components like fans, electrolytic capacitors which lead to a "natural death"

3) Unexpected real world conditions (bad grid voltage quality, bad installation, interaction with other devices on the same gr ...

A phase rotation meter, through the use of its six terminal leads, compares the phase rotation of two different 3-phase connections. Three leads, labeled "A," "B," and "C," are connected to the test unit's side labeled "MOTOR." Three other leads are labeled the same but are connected to the test unit's other side, which is labeled "LINE." The meter also has a zero-center voltmeter, with one side labeled "INCORRECT" and the other labeled "CORRECT."

First, you "zero" the meter per t ...

One operational point is to leave a surge buffer at the top of the tank, based on maximum possible input flow. I would eliminate the control valve, to use the VFD, but you may need a stop valve if the discharge of the pump allows gravity flow, when the pump is stopped for Low-Low Level, for instance. A stop valve is easier to apply and more reliable than a vacuum breaker on the discharge line.

The VFD provides significant energy s ...

Loops can be:
4÷20mA 2÷10V
2÷10mA 1÷5V
0÷20mA 0÷10V
0÷10mA 0÷5V

For example if we have a 4 ÷ 20mA loop, it will have a range of 20mA - 4mA = 16mA. This is domain.

By convention 4mA is the lower limit (LL = Low Limit) and 20mA upper limit (High Limit = HL), the rest of the field values are intermediate states (points).

How can we force the lower limit, quite simply, send 3 ...

With an Inductive Load such as a Motor, there is both Resistive load and Inductive Load. . . . The Resistive load is largely from the Mechanical Work being done, so can vary. . . . The Inductive Load creates the Magnetic field and does not significantly change, regardless of the Mechanical Load on the Motor.

When this Resistance & Inductive Load is put on to the Generator, it is only the Real or Resistive Load part, that is the kW part, that the Engine sees, so there is no cha ...

There are several reasons you see inverters in such heavy use in renewable energy. You have the problem of converting from one voltage level at the source, to a substantially different voltage. And the source voltage can vary substantially. To do this, you must employ some type of alternating-or-pulsed input to a conversion system. And, that system must include an inductive device. I.e., a coil or transformer. A dc up-conversion would be almost impossible otherwise, and a dc down-conversion w ...