OK, I can’t believe I left this out but rather than edit, I’ll just do it as a new post. When you are applying a VFD to a hoist, you have to understand that not all VFD‘s are capable of being used for this. You need one that is capable of close loop flux vector control, and has a feature called...
There are multiple kinds of braking technology to go with AC motors. Dynamic Braking (DB) is one type, DB pulls the kinetic energy of the rotating load into a DC bus and then burns it off into resistors. It is very commonly used for motors with VFDs because it is dirt cheap to add it to the VFD...
Bill had it correct in the first response. The main difference in closed loop is that by knowing the exact rotor position and any given moment, the current used for establishing stator flux can be minimized to exactly what it requires at that moment, leaving the rest of the available current...
“Partial” PM motor support could mean that they support IPM (Internal Permanent Magnet) but not SPM (Surface Permanent Magnet) motors, or some combination. For example the PowerFlex 525 drives are like that. You can use them in Open Loop on SPM and IPM motors, but if you want closed loop, it...
By virtue of the use of “earth fault” instead of ground fault, I hazard a guess that the OP is not in North America, so rules and terminology are different.
An MPCB is a thermal-mag circuit breaker with adjustable thermal trips. We use them here, but many people are as yet unfamiliar with...
I call these sort of numbers "Marketing values"... used to mislead consumers about "More power!", when in fact they are referring to values that cannot be sustained for more than a few seconds.
How thorough do you want to be and how much are you willing to spend for it? If there is only going to be ONE window for IR scanning, it is typically put on the termination compartment, because that is the most common point of failure. The breaker, if it in vacuum, is harder to scan as far as...
If you crunch the numbers, the V/Hz ratio is staying fairly close to the same at those different voltages and frequencies, approx. 8.2:1, and torque is determined by that V/Hz design ratio of the motor. So the difference in PN (which is the nominal MECHANICAL power rating of the motor) can...
The output voltage of a VFD can be tailored to be whatever the motor nameplate voltage is. So when you program the motor nameplate data into the drive as it being a 440V motor, the drive will (should) limit the voltage at full speed to 440V.
That said, the other concerns raised are very valid...
One thing left out of the above is that the synchronous motor what’s called sn “amortisseur” winding that mainly functions as a dampener against load torque fluctuations, but ALSO allows the synch motor to act as an induction motor to start from a stop. A synch motor cannot self start with...
Ball Mill Super Capacitors
At 7MW for 300 seconds, you are not going to get anything remotely close to that with "super capacitors"... You can buy what are called "UPD" (Uninterruptable Power for Drives) systems for LV drives that use super capacitors, they will give up to 2 seconds! After that...
Muthu,
As a gross general rule, VFD mfrs typically tell you not to go below 50% of the VFD rated amps. That's because the current sensing technologies used in most drives, which are crucial for any form of vector control capability, run into error rates that effect performance at low speeds and...
The kW rating of a motor is a shorthand expression of a torque value at the rated motor speed. So just saying "22kW" is not enough information to make that determination. What is the base motor speed of the 22kW WRIM, and what is the base motor speed of the replacement SCIM that you want to use...
The inherent problem in paralleling thyristors is that they are constant voltage drop devices, but finding two that are the exact same voltage drop is virtually impossible. So the one with the lower VD, no matter how small of a difference, will hog the current. Then you combine this with the...
I like to look at IEEE-519 as being the Tablet brought down from the mountain that says only one commandment:
"Thou Shalt Not Infect Thy Neighbor's Facility with Your Harmonics!".
So then you have to look at harmonics like it's a "population of a country", which is made up of individual cities...
