vfds

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 ...

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 ...

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 ...

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 ...

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 ...

If the variable frequency drive (VFD) has a load of 1000KW, then the low frequency impedance must be fairly low to prevent excessive voltage drop. The problem is what the high frequency impedance looks like and whether there are any local supply resonances in the KHz range.

We see a lot of problems on the power supply with common mode, often coming from the output of poorly installed VFDs. Issues due to active front end and actives filters can be so much worse. It is both equipmen ...

The resistor breaking in an AC motor variable frequency drive (VFD) consists of a switching power converter where the back EMF of the motor acts as the voltage source and the converter is controlled by the duty-cycle to produce a variable voltage across the breaking resistor. The voltage is increased to the breaking resistor by increasing the control duty-cycle and this produces an increasing armature current with a torque that resists the mechanical shaft torque resulting in breaking. The me ...

Problem:
Pump type is a piston dosing pump with manual struck length adjustment with motor 3 phase 220 AC volt delta connection variable speed. We control it with a GK3000-2S0007 1 hp variable frequency drive (VFD) single phase 220 VAC to three phase output. We control the dose of the pump through the VFD with analog reference signal 4-20 mA which effect the frequency (V/F) which change the motor speed rpm. The problem is at low required dosing ...

I think there are a few more differences between different variable frequency drive (VFD) designs. For example: I've used VFDs that never use output load reactors, and can go, depending on the VFD model, 300 to 1000 Ft between the VFD and motor unaided. To exceed that distance, they use an RFI filter. Not tooting a horn, but pointing out one of the manufacturer's capabilities versus others, with respect to wanting to define the application as thoroughly as possible before taking on system des ...

Generally the variable frequency drive (VFD) operating temperature range is -10 degrees C to 40 degrees C. I would not be too concerned about the upper operating temperature limit (40 degrees C) as it is rather simple to derate the VFD for high thermal limits. The same goes for the high elevation application as the VFD will have some additional derating due to the lower thermal mass of air at high altitude. One might check with the VFD manufacturer to determine if that variable speed drive ha ...

In variable speed drive (VSD) systems, both AC and DC, the first stage of power conversion is from AC to DC. In a DC drive, it's the only stage - from fixed AC to variable DC. In an AC drive there are two additional stages: filtration and inversion back to AC.

The simplest converter is a full-wave diode bridge, which converts the incoming AC to a fixed DC voltage. This isn't useful in a DC drive, but works fine for AC variable frequency drive (VFD). Standard industrial drives - bot ...

If you talk to someone in variable frequency drives (VFD) sales, they will often tell you that there is no place for a soft starter because the VFD reduces the current more than a soft starter and the VFD saves energy, but in reality there is definitely a place for both of them. If you need to vary the speed of the driven load, then a VFD is definitely the choice. If you are looking to reduce the starting current and the starting torque of an induction motor, then a soft starter can be select ...

The point is, if the motor is running at nominal load, the energy saved when using a variable frequency drive (VFD) is about 3%, for 75% load is about 25%, for 50% load is about 75%. So to calculate how much energy saved by the VFD, you have to check how long the pump/motor will run on under nominal load conditions and how big is the difference between nominal and operating load. Now, this x% has to be translated in kWh and then in money. This money you have to compare it with VFD price and s ...

In my experience, after the hundreds that I have had to design & work with, over 27 years, there are a lot of physics & understanding that is associated with different applications that are possible. What it will ultimately come down to is motor construction and variable frequency drive (VFD) capabilities and size, based on specific application. There are also a few questions that must be answered before a solution will be specified. We have to deduct that some equipment is already in ...

A 12 pulse variable frequency drive (VFD) will develop a harmonic signature with high magnitudes on the 11th and 13th order. The good thing is the typical harmonic signature exponentially falls off as the order goes up. This is the reason that an 18 pulse VFD will have less harmonics than a 12 pulse VFD and so on and so forth. Another advantage is the DC buss will have less distortion when a multi-pulse front end is used. Most medium voltage VFD comes standard with 24 or 36 pulse front ends. ...

The brief observations that follow will assume that you have a 3 phase permanent magnet (PM) AC motor. In a PM AC motor, max continuous torque is achieved when the stator MMF (or current) vector is 90deg displaced from the rotor's flux vector. Recall the Torque = Rotor_Flux x Stator_MMF ... i.e. the torque is the vector cross product of the vector Rotor_Flux with the vector Stator_MMF, or Torque = |Rotor_Flux| * |Stator_MMF| * sin(theta), where theta is the angle between the two vectors. Torq ...

There has been a couple good thoughts as to why a variable frequency drive (VFD) would fail after powering back up, moisture will be a big player in the operation of a VFD but I will caution you about blowing air across a VFD. The components are a little picky when it comes to static and that can be all it takes to kill it. I have a couple MCC rooms that the VFDs are covered with powder and that's a concern but the greater concern is getting the powder off without incident. We have been succe ...

Inverters can be adapted from stall right up to CHP ranges, only design limits are feedback device and proper cooling aspects to the machine load profile. Some applications require extended low speed performance. Normally the variable frequency drive (VFD) supplier indicates speed range capability based on type of VFD and feedback device required.

There may be some confusion between frequency and motor speed.
Open loop, typical speed regulation is plus or min ...

Variable frequency drive (VFD), also called frequency inverter, variable speed drive (VSD), adjustable frequency drive (AFD). This article is about the basic guide of how to select a VFD.

The correct selection of the variable frequency drive (VFD) is critical for the normal operation of the mechanical equipment electrical control system. To choose the best suitable VFD, we need to know the specified machinery type, the load torque characteristics, speed adjusting range, static spe ...