Main Features

Digital Inverters
The DFNT series of inverters is designed for open-loop control of three-phase asynchronous motors. They combine ease of use and high flexibility with excellent control characteristics. The optimization of modulation types (SVPWM and DPWM) allows for overmodulation operation, ensuring good stability even at high frequencies (2 to 3 times the nominal frequency) during flux weakening.

Standard Special Functions

• Motor interface with autotuning for optimization at low speeds
• Start-up on rotating motor
• Slip compensation
• Motor stall protection
• Current derating curve selection for self-ventilated motors
• Initial boost capability for starting under load

Technology and Control

• "Energy Saving" function to optimize current delivery at constant torque
• Overmodulation for voltages up to 10% above network voltage with reduced harmonic content
• Frequency jump with two adjustable "bands"
• Braking with DC current injection
• Compensation for network micro-interruptions with regenerative operation
• Braking with DC bus voltage control limiting maximum regenerative torque
• Automatic inverter temperature monitoring system

Setup and Programming

• PC supervision software with electronic oscilloscope function for easy commissioning and drive diagnostics
• Parameter and alarm storage and display
• RS 485 serial port with Modbus protocol (RTU or ASCII)
• Programming and diagnostic keypad with logical parameter grouping
• Fieldbus programming and diagnostics (optional)

Power Specifications

• Three-phase power supply 400 ÷ 440V - 15% + 10%, frequency 50/60 Hz ± 5%
• Power supply from external DC bus
• IGBT power structure
• Switching frequency: 3 ÷ 9 kHz selectable
• Static precharge device with automatic or external command insertion
• Maximum overload: 150% for 30 sec (S1), 200% for 30 sec (S2)

Control and Regulation

• Full digital regulation with high computational capabilities (DSP)
• Frequency regulation with internal torque loop and max current limit
• Output frequency: 0 ÷ 1,300 Hz
• Programmable V/F characteristic (linear, quadratic, or point-based)
• Independent ramps with linear or S-profile

Protections

• Stored and displayed protections via display or serial line:
• Phase-to-phase/phase-to-ground short circuit
• Braking resistor short circuit
• Inverter overtemperature (radiator thermal pad or NTC)
• Motor overtemperature
• Motor overload
• Overvoltage and undervoltage

Signals and References

• 8 opto-isolated digital inputs
• 3 ± 10 V analog inputs for frequency (speed) reference, torque reference, torque limit
• 3 configurable opto-isolated digital outputs
• 2 programmable ± 10 V analog outputs
• 3 internal digital jog speed references
• Digital potentiometer function with increase/decrease logic inputs

Options

• Communication boards: CAN BUS (CANopen), PROFIBUS DP
• RS 232 / 485 converter for PC connection with supervision software
• Remote keypad for drive parameter setting
• Braking circuit preparation
• Braking resistor
• Line reactors
• EMC filters
• Preparation for 4-20 mA analog inputs

Dimensions
Various dimensions are provided for different power ratings, ranging from 1.5 to 110 kW, with specific height, width, and depth measurements.