If the Motor is pre-EPAct (1992), it should be run on VFDs only with careful consideration. Motors made during that time were not made for VFD use, but if they are VFD rated, will be okay. Class F insulation or higher is suitable for VFD use, but VFDs may have no more than a 2:1 Constant Torque ratio.
Can any motor be used with a VFD?
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.
Can all electric motors be variable speed?
In general if you don’t do anything special to it, a DC motor will have variable speed. The main factors are the DC voltage applied to the armature coil and the amount of torque load you are trying to drive. In order to make it into a constant speed DC motor you have to have some sort of electronic feedback.
Do you need a special motor for 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. The manufacturer should be consulted directly for determining the winding insulation of a specific motor. …
How do you select a VFD for 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.
How does a VFD slow down a motor?
They control motor speed using pulse width modulation, whereby waveform alteration rather than voltage adjustment is used to slow down or even speed up off-the-shelf induction motors relative to nameplate values, provided shaft bearings and cooling are up to the task.
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 you slow down an electric motor?
Slowing down a single phase AC motor can be complicated and expensive. They are usually built to be run at a certain speed and anything else would be tricking it to do something it wasn’t meant to. Simply slowing it down may cause it to overheat with reduced mechanical self-cooling.
Can you put 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.
Can you slow down a single phase motor?
Generally, single phase capacitor-start motors cannot be speed controlled. It’d be ok, but only for a narrow range of speeds. Once the speed reached the start winding switchover, speed control would be impossible.
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.
How do you know if a motor is inverter duty?
Motor insulation systems that are rated for inverter use will be specified on the motor nameplate (or a sticker). These systems should have wire rated for a minimum of 1600 volt spikes, F or H class insulation, and will be processed with 100% sold resin in a vacuum pressure impregnation (VPI) system.
How long will a VFD last?
about 7-12 years
Can you oversize a VFD?
You can’t go too big, because big VFD’s may not allow adjustment of the VFD motor amperage setting low enough for a small motor. If you overloaded motor, VFD would cook it… You should be fine, with a 3kw running a 1 kw motor…
How many motors can a VFD control?
With one VFD per motor, each motor can be controlled separately and run at a different speed. This is not so when running multiple motors from one VFD. Second, running multiple motors from one VFD creates a single point of failure.
How is VFD calculated?
- Step 1: 60 hp × 0.746 = 44.76 kw1
- Step 2: 0.28 ratio × 44.76 kw1 = 12.53 kw2
- Step 3: 0.88 ratio × 44.76 kw1 = 39.39 kw3
- Step 4: 39.39 kw3 – 12.53 kw2 = 26.86 kw4
- Step 5: 26.86 kw4 × 8,760 hr × $0.12 per kwh = $28,235 (annual savings)