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INVT Application Notes and Commissioning Guide
This section brings together practical commissioning and field-service information for INVT variable frequency drives. It covers the subjects most often encountered during installation and machine setup, including motor data, command sources, frequency references, acceleration and deceleration, braking, PID control, Modbus RS485 communication and fault diagnosis.
Although many INVT Goodrive families follow a similar operating philosophy, parameter numbers and available functions can differ between models. Always confirm the exact drive model, voltage class, motor rating and relevant user manual before applying settings to a machine.
Basic Checks Before Commissioning
- Confirm that the incoming supply matches the voltage class of the VFD.
- Check the U, V and W motor connections.
- Verify protective grounding.
- Read the motor nameplate and confirm rated voltage, current, frequency, power and speed.
- Decide whether the run command will come from the keypad, terminals or communication.
- Select the required frequency-reference source.
- Set acceleration and deceleration times according to the machine.
- Make sure the motor and mechanical system are safe before the first RUN command.
Motor Nameplate Parameters
Correct motor data is important for both control performance and protection. The rated motor current is particularly important because overload protection may not operate as expected if this value is entered incorrectly.
Motor voltage, frequency, power and rated speed should also be checked whenever a drive is commissioned on a new motor. If an INVT drive is moved from one machine to another, do not assume that the old motor parameters can be reused without verification.
Selecting the Run-Command Source
Depending on the drive model and application, RUN and STOP commands may be taken from:
- The operator keypad
- Digital input terminals
- PLC or relay outputs
- RS485 / Modbus communication
If the VFD has no active fault but does not respond to a RUN command, check the configured command source. For example, a drive configured for communication control may ignore a RUN signal applied to a terminal input.
Frequency and Speed Reference
The motor speed reference can also come from several sources:
- Keypad potentiometer or digital keypad setting
- 0–10 V analog input
- 4–20 mA / 0–20 mA analog input
- Multi-step speed inputs
- Built-in PID control
- RS485 / Modbus communication
If the motor runs but does not follow the expected speed command, check not only the output frequency but also which frequency-reference source is currently active.
Acceleration and Deceleration
An excessively short ACC time can produce high motor current during acceleration and may lead to overcurrent trips such as OC1. A very short DEC time can cause regenerative energy from the motor to raise the DC-bus voltage and may result in overvoltage faults such as OV2.
Acceleration and deceleration settings should therefore be selected according to machine inertia, mechanical load, braking requirement and operating cycle, not only according to motor power.
Braking Resistors and Regenerative Energy
High-inertia machines, centrifuges, hoists and applications requiring rapid stopping can return significant energy from the motor to the VFD during deceleration.
If the DC bus cannot absorb this energy, an overvoltage trip may occur. Depending on the application, the solution may involve a longer deceleration time or a correctly selected braking resistor and braking unit.
Braking resistor selection should consider the resistor value, minimum permitted resistance, required resistor power, stopping time and braking duty cycle.
PID Control Applications
Built-in PID control can be used in applications where a process variable such as pressure, flow or level must be maintained automatically.
Before tuning PID operation, check:
- PID setpoint source
- Feedback source
- 0–10 V or 4–20 mA sensor range
- PID operating direction
- P, I and, where required, D settings
- Behaviour in the event of sensor or feedback loss
On some INVT drive families, loss of the configured PID feedback signal can generate a PIDE fault.
INVT Modbus RS485 Communication
Many INVT VFDs can be integrated with PLC, HMI or SCADA systems through Modbus RTU / RS485.
The following communication settings must match between the VFD and master device:
- Slave address
- Baud rate
- Parity
- Stop bits
- Register-addressing convention
Depending on the model, run commands, direction, frequency reference and operating data can be transferred through Modbus registers.
+ INVT VFD Modbus Address Reference
When RS485 Communication Does Not Work
If the PLC, HMI or SCADA cannot communicate with the drive, check more than just the register address:
- Verify the RS485 A/B wiring.
- Check the slave address.
- Confirm baud rate and parity.
- Keep communication wiring away from motor and power cables.
- Check shielding and grounding.
- Confirm whether the PLC/HMI uses zero-based or one-based register addressing.
Programmable Digital Inputs
INVT digital inputs are not limited to simple forward and reverse commands. Depending on the model, inputs can be assigned to JOG, fault reset, multi-step speed, external fault, PID pause and command-source selection.
If a digital input does not perform the expected function, check both the physical wiring and the parameter assignment for that terminal.
Using Fault History for Diagnosis
GD10, GD20 and many other INVT drive families store both fault history and operating data captured around the time of a trip.
Useful diagnostic values can include:
- Fault code
- Output frequency
- Motor current
- DC-bus voltage
- Drive temperature
- Digital input and output status
For example, motor current is especially useful when investigating OC faults, DC-bus voltage is important for OV faults, and temperature records are useful when diagnosing OH faults.
Replacing an Existing VFD
When replacing a failed drive with another INVT VFD, do not transfer the old parameter set without checking the application first.
Review at least the following:
- Motor nameplate data
- Run-command source
- Frequency-reference source
- Digital input functions
- Analog input type
- ACC / DEC times
- Minimum and maximum frequency
- PID settings
- Modbus address and communication parameters
Model-Specific INVT Technical Pages
+ INVT GD10 - Specifications, user manual and fault codes
+ INVT GD20 - Specifications, braking data, manuals and fault codes
+ INVT GD200A - User manual, troubleshooting and braking information
+ INVT GD350A - High-performance VFD applications
Related INVT Technical Resources
+ INVT User Manuals and Technical Documents
+ INVT General Fault Codes and Troubleshooting