Output voltages are available for VFDs to match almost any existing motor voltage. However, very few, if any, VFDs have a direct 13,800-volt output for very high-voltage motors. For these cases, using a step-up transformer on the output of the VFD is often necessary to match the motor voltage.
What motors can be used with VFD?
The AC electric motor used in a VFD system is usually a three-phase induction motor. Some types of single-phase motors or synchronous motors can be advantageous in some situations, but generally three-phase induction motors are preferred as the most economical.
How do you tell if a motor can be used with a VFD?
Three major factors should be considered when determining if a motor is compatible with a VFD: the motor winding insulation, motor bearings and pump operating speed range.
Can a VFD damage a motor?
1. VFDs can wreck motor windings. VFDs control motors with a simulated sine wave known as pulse width modulation (PWM). The problem is that peak voltages created by the VFD can often get high enough to break through motor insulation and short out motor windings.
Can a VFD be used on any 3 phase motor?
Using VFDs To Convert Single-Phase To Three-Phase
Like most things, however, there is not a simple answer to this question. … Yes, a VFD can power a three-phase motor with a single-phase input power supply, but phase conversion introduces many considerations that normally don’t factor in to buying a VFD.
How do I choose a VFD for my motor?
Thus, the rule of thumb for sizing the single phase input on a three-phase drive is to use a VFD rated for 2 times the FLA of the motor. For example if your motor is a 10 HP motor with a FLA of 28 amps, then you would need to select a VFD with an amp rating of 56 amps which ends up being around 20 HP.
How does a VFD work on a motor?
VFDs manipulate the frequency of their output by rectifying an incoming AC current into DC, and then using voltage pulse-width modulation to recreate an AC current and voltage output waveform. However, this frequency conversion process causes 2% to 3% loss as heat in the VFD — caloric energy that must be dissipated.
How slow can you run a motor on a VFD?
Generally speaking, TEFC motors are not designed to operate at less than a 4:1 speed range, while some manufacturers make a 10:1 or 20:1 range motor. Most often, operating the motor slower than this requires an auxiliary cooling system. This threshold can be higher depending on the torque the motor is providing.
Can VFD causing motor vibration?
Circulating bearing currents—related to the use of VFDs—are primarily caused by the speed of the inverter switching in the output stage of a VFD. … Over time, this pitting creates a fluting on the face of the bearing races. When the fluting becomes severe enough, bearings can fail, which causes increased motor vibration.
What is the danger of running a VFD drive too slow on a motor?
An inverter duty motor can deal with the higher voltage spikes produced by VFDs also can run at very slow speeds without overheating. The general purpose motor don´t, it can overheat if it is running too slowly, so bearings and insulation will be damaged.
What causes VFD failure?
If you are having erratic performance from your VFD, loose connections and bad/aging components are likely causes. Vibration and heat cycles are typical causes of loose connections which can then lead to dangerous arcing. Arcing at the output can damage other components and cause over-current faults.