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.
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.
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.
Can a VFD damage a motor?
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.
How do you match a VFD to a 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.
What does a VFD do for a motor?
A variable frequency drive (VFD) is a type of motor controller that drives an electric motor by varying the frequency and voltage of its power supply. The VFD also has the capacity to control ramp-up and ramp-down of the motor during start or stop, respectively.
Can a VFD be used on any 3 phase motor?
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.
When should you not use a VFD?
Does every motor need a drive? When NOT to use a VFD
- This motor’s load is fixed and unrestricted. …
- You need this motor to operate at very low or very high speeds. …
- You’re planning to install this drive on a motor that is more than 15 years old. …
- You have power quality issues. …
- You cannot place the drive within the manufacturer’s maximum tolerable distance of the motor.
Do you lose HP with a VFD?
When the VFD reduces frequency and motor speed, it also reduces voltage to keep the volts/hertz ratio constant. Torque remains at 100 percent, but HP is reduced in direct proportion to the change in speed. At 30 hertz, the HP is just 50 percent of the 60-hertz HP.
How many motors can a VFD control?
A single variable frequency drive (VFD) may control 2 or 3 motors at a time, multiple motors control is usually done because of budget considerations. When in this example below, a cooling tower with 4 equally sized motors are controlled by one variable frequency drive.
Does a VFD replace a motor starter?
VFD does essentially replace a motor starter in applications where they are used, there still can be control schemes where a contactor may be used to interrupt power – typically only for occasional shut down situations and not as a routine control method – VFD’s don’t play well with contactors in the circuit, total …
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.
How slow can you run a motor on a VFD?
Any VFD is capable of telling a motor to run at 1Hz or 1/2Hz or 0.01Hz, but that does not mean the motor will do that without damage. So there are different DESIGNS of motors available, and those that are designed for operation on a VFD are called “inverter duty” (or something to that effect).
How much does a VFD cost?
Typical installed costs of VFD systems range from $200 to $500 per horsepower (HP). Suppliers can assist users in selecting a VFD that is properly sized and that includes any necessary filters and reactors.
Which VFD is best?
In low voltage VFDs, we think the best VFDS on the market are the WEG VFD, the Yaskawa VFD, the Toshiba VFD, the LSIS VFD, and the Teco VFD (especially in the high horsepower low voltage models) All of these are good companies with well designed reliable equipment.
Can I use a VFD on a single phase motor?
In general single phase motors cannot be run with VFDs. However, it is possible to input single phase to a VFD and output variable voltage to a 3-phase induction motor.