This reference consolidates the supplied VFD installation guidance for input-power selection, motor-cable limits, overload protection, acceleration and deceleration, and input reactors. Because the evidence does not identify a manufacturer or model, verify every recommendation against the selected drive manual and ratings before installation.
Select the VFD Input Supply and Capacity
Applying single-phase power to a VFD intended for three-phase input increases DC-link capacitor ripple, may damage the power capacitor, and can reduce torque performance. When single-phase input cannot be avoided, the supplied guidance recommends selecting a VFD with approximately twice the motor capacity. Confirm that the specific drive permits single-phase input; the evidence does not define voltage, current derating, or an approved model range.
Size and Limit the Motor Cable
Long VFD-to-motor wiring increases voltage drop, which can reduce motor torque, especially at low output frequency. Select conductor size so voltage drop remains within 2%. Cable capacitance can also produce charging current and unintended overcurrent trips.
| VFD-to-motor distance | Maximum carrier-frequency setting |
|---|---|
| Up to 50 m | 15.0 kH or lower |
| Up to 100 m | 10.0 kH or lower |
| More than 100 m | 5.0 kH or lower |
The source recommends limiting wiring to 300 m and also states an absolute maximum of 500 m, without explaining the conditions that distinguish those limits. Treat 300 m as the stated design limit and do not approach 500 m without model-specific approval. The carrier-frequency unit appears in the evidence as “kH”; verify the drive parameter unit rather than silently interpreting it.
Configure Motor Protection and Ramp Times
The VFD's electronic thermal function can protect one motor from overheating, so the supplied guidance does not require a separate output thermal relay for that arrangement. Install a thermal overload relay between the VFD and each applicable motor when one VFD operates multiple motors or when it operates a multipole motor.
Set acceleration and deceleration times from available motor torque, load torque, and load inertia. If current limiting or stall prevention activates during a ramp, increase the ramp time. To shorten the ramp, the evidence identifies three options: install a correctly rated external dynamic-braking resistor, increase torque boost, or select a larger VFD. Excessive torque boost can cause starting overexcitation current and an overcurrent trip.
Determine Whether an Input Reactor Is Required
The supplied guidance requires a power-factor-correction reactor when the VFD is connected within 10 m of a 1000 kVA supply transformer or when input-voltage variation is 3% or greater. A nearby high-capacity transformer can drive excessive peak current into the VFD input circuit, while excessive voltage variation can damage the converter diode module. Verify reactor sizing and placement in the applicable VFD documentation because no reactor rating is provided.
FAQ
Can I power a three-phase-input VFD from single-phase power?
The supplied guidance warns that this increases capacitor ripple and may reduce torque or damage the power capacitor. If unavoidable, it recommends a VFD rated at approximately twice the motor capacity, subject to confirmation that the selected model permits single-phase input.
How long can the cable between a VFD and motor be?
Keep voltage drop within 2% and use 300 m as the stated design limit. Although the evidence also gives 500 m as a maximum, it provides no qualifying conditions, so obtain model-specific approval before exceeding 300 m.
When does a VFD need an input reactor?
According to the supplied guidance, install one when the VFD is within 10 m of a 1000 kVA supply transformer or when input-voltage variation reaches 3% or more. Confirm the reactor rating using the selected VFD documentation.
