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 know 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 you put a VFD 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.
How do you select a VFD for a motor?
The most important consideration when choosing a Variable Frequency Drive (VFD) is to know the type of load that is being applied to the motor because it will determine the size and cost of the VFD. The VFD must have sufficient current capability so that the motor can produce the required torque for the load.
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.
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.
How do you derate a VFD?
The formula we use to derate variable frequency drives for single phase power is as follows: AC electric motor current multiplied by 1.73, then size three phase (vfd) variable frequency drive with the corresponding amps. Most times to derate a three phase VFD for single phase power can be done by going up one size.
How much can you overspeed a motor with a VFD?
Motors generally have to withstand 10 % overspeed. But it in no way means many motors cannot withstand much higher over speeds.
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.
Can you soft start a single phase motor?
Single phase soft starters are designed to start up single phase motors smoothly, reducing initial shock and improving the longevity of mechanical system components. In addition, soft starters can reduce starting current in order to limit peak energy demand.