Blog

VFD means Variable Frequency Drive, by using VFD you can use AC motors on highly controlled way. VFDs slightly adjust frequency based on given parameters and AC motors are able to achieve even extreme options for example zero speed at max torque (brake operation mode). AC motors are much less sensitive than DC ones so using VFD and AC motors after SCR and DC motors is a really joy.

Applications of VFD are becoming very common and continually get benefits from it. Basically the app ...

Variable frequency drive (VFD) is a whole science and even a very broad deliberation here will not give you any good picture. I was teaching VFD course for one of the manufacturers and for an introductory session I talked for 8 hours, full course - 5 days and this is still just facts. Surely, you can buy 1HP VFD hook to 1HP motor and it is going to work regulating the speed by a pot on it. However, if you buy 4MW (that is 4 mega watts) VFD to run pil ...

Why humming noise from variable frequency drive (VFD) driven motor. Why is it so? If the application is not demanding you can "regulate" the sound and its pitch. Get into the VFD parameters and find "carrier frequency". Typical values are about 2-15 kHz. Then set it to 2 kHz and run the motor - if you have a musician ear - note the noise. Then go back and set 4 kHz and repeat the procedure +++ until you run the motor on max. kHz carrier. Have you noticed the change in the hum noise? Remember ...

Just a note of caution if you are going to use a variable frequency drive (VFD) on an existing motor it should be manufactured with at least Class F insulation and be rated for inverter power source. Because of the PWM (Pulse Width Modulated) waveform there is residual heating and most motors will go to 1.0 SF from 1.15 SF. There can also be issues relating to lead lengths in excess of 100 feet or more, output filtering may be required, ie. ...

A VFD is shortened for variable frequency drive it's a sort of AC drive which control the speed of the ac motors depending on frequency change. VFD is very useful in industry today, but much thought to the application must be taken. For example, if you are controlling motor speeds at or below 50% to 75% (and maintaining them in this range), you may want to consider changing motors to a different RPM. VFD produces harmonics that ca ...

Star connected motors have a central connected point, called a short circuit point or star point and each winding receives phase voltages (230volts), star connected motor only run at one third of the motor rated torque and power, whereas delta connected motors have no connected point and each winding receives line voltages (415volts) and operates at full torque and power.
...

I believe you are more concerned with why a single motor should be running using 2 variable frequency drives (VFD):
The primary requirement will be catering critical application where the shutting down of the motor is not feasible just in the VFD fails so we go for redundancy concept which is possible in certain makes of VFDs.

Load sharing is also a requirement in order to avoid loading of a single VFD and reducing its life, where 2 VFDs of motor FLC is selected but ran on 5 ...

What really happens with a variable frequency drive (VFD) / variable speed drive (VSD) and the actual frequency that is imposed on the electric motor terminals? For induction motors, it is never 0 Hz. For synchronous motors - it can be DC / 0 Hz - but this is only in the case of Permanent Magnet Synchronous machines, and motors with Wound Fields that have the ability to supply significant Current into the wound fields at standstill.

I am not going to discuss synchronous motors fur ...

HVDC means High Voltage Direct Current and it enables controllable exchange of Active Electrical Power between two stations since the two stations in case of their being connected over HVDC link. As any electrical engineer would know, flow of power between two ends of a transmission line would comprise two components one of which would be Active Power measured in Watts (W) or kilo Watts (kW) or Mega Watts (MW) etc, and the other component wo ...

In the design work for a project to convert from single phase to three-phase AC power supply, where should we start implementation of the project? What problems might face in converting single phase to three phase power and how to avoid them?

We can change 1 phase power to 3 phase like any other power project; determine ...

AC power systems around the world have different frequencies. Inverter grid synchronization with phase locked loops handles frequency and phase variation. What AC power system frequencies do you expect your power converter to deal with?

"Utility side" frequencies: 25 Hz, 50 Hz, 60 Hz, 240 Hz, and 400 Hz. Include a +/- 5 percent range for each, to cover system instabilities. "Harmonic" frequencies found on incoming line: 5th, 7t ...

Any non-linear load (such as a computer, a microwave oven, some refrigerators and electric stoves, or a variable frequency drive) will generate harmonics to some extent. Motors and generators themselves - because of inherent dissymmetries in the manufacture - can create some as well. The variable frequency drives that are referred to as "active front end" topologies are probably the worst, since their whole approach is to introduc ...

Variable frequency drive (VFD) operation with voltage and frequency control of the induction motor was acceptable for most applications. There were certain machines that DC motor control had some technical advantage. The VFD needed more intelligence to know the true load of the motor. An AC machine requires a magnetizing current to operate at no load. This current is not actually a lot of power, but looks like the induction motor always has 20 to 30% load. The DC machine load on the armature ...

HVDC has been in existence for a long time but has become so popular these days with weighing advantages for the traditional HVAC transmission technology. HVDC system uses direct current for the bulk transmission. There are different configuration, types and topologies to include HVDC back to back, classical HVDC, etc.

The advantages lies in the fact HVDC links are able to connect to two asynchronous network, a typical example is a 60Hz and 50Hz ...

Variable Frequency Drive, in short VFD, it can be called VVVF drive, variable voltage and variable frequency to change this from sinusoidal AC, the VFD changes the AC to DC first then DC to AC by using IGBT, this is done by firing IGBT very fast (carrier frequency), so this output is not sinusoidal.

If you want to know how does a VFD work, you should hit up Wikipedia or Google it, lots of articles out there. If you're wondering about how to use a VFD, there are numerous considerati ...

You can find a simple explanation of what an induction generator can do. It is totally self-synchronizing with the grid it is feeding power into. It stays in sync and delivers energy as long as it is driven at an rpm higher than its synchronous speed. If it is feeding a 50 Hz power supply it must be driven 2% to 5% above ts sync speed. Sync speed is 120 X frequency / number of poles thus a 4 pole machine ...

Required or not, ground ring provides a better (lower impedance) grounding system. It really depends on what the specifications of the project call for. Here, ground rings are typically only used for sensitive electrical equipment installations - such as computer/data/network server rooms. For industrial/motor control/general light and power applications, a properly sized equipment grounding conductor (green wire), sized in relationship to the overcurrent protective device, is installed in th ...

I would certainly say that thyristors are indeed extremely robust. Many IGBTs are designed to deliberealy limit the max current they can supply to limit short circuit currents and then allow a slower ("soft") turn off within the 5-10us s/c withstand time. So if you want very high peak to average current rating it may be this deliberate thing that is working against you.

Thyristors are 4-layer devices with two sources of carriers in difference with IGBTs. They operate at higher pla ...

Lot of literature can be found in French since France and Quebec are the countries where the HVDC transmission is very developed and already mature technology.
Why it is used? The answer is to avoid corona effect which is a source of energy losses, which are between 5-8% of the nominal installed power (huge if you compare with the power of a single transmission line). For this reason almost all of the long distance transmission lines from Siberia to European part of Russia are HVDC whic ...

An Active Front End (AFE) Drive installation where shutting off the filter would also shutoff the variable frequency drive (VFD). This is truly a serious and widespread problem that the AFE Drive manufacturers don't want anyone to know about. In fact, they actively promote their AFE 'low harmonic drives' as the ultimate solution. I chuckle when I watch one elaborate video produced by an AFE drive manufacturer that properly highlig ...