Product Description:

The VLT 6003 is an AC variable-frequency HVAC drive produced by Danfoss as part of the VLT 6000 HVAC Drives series. It is intended to regulate induction motor speed in air-handling units, pumps, and other building service equipment, allowing energy savings through precise airflow or water flow control. The unit connects directly to a three-phase power supply and provides closed-loop torque control for common plant automation tasks. Its variable-frequency output allows connected motors to operate at the speed required by the process instead of running continuously at full speed.

The inverter provides a typical shaft output of 1.5 kW, while its input stage maintains a true power factor of 0.90 to minimize reactive current. Motor starts are supported by a starting torque reserve of 110% for 1 minute, and immediate load breakaway is handled by a peak torque of 160% for 0.5 seconds. The power terminals are rated to withstand prospective fault currents of up to 100,000 A. The control electronics include one analog current input, two analog voltage inputs, and eight digital inputs. The analog path is decoded with 10-bit-plus-sign resolution, allowing the controller to process speed references and feedback signals accurately. Three high-speed pulse inputs support incremental encoder signals, operating at 5 kHz on terminal T17 and at 65 kHz on push-pull terminals T29 and T33 for frequency feedback.

Field wiring can use a motor cable with a maximum conductor cross-section of 4 mm², accommodating the current requirements of the connected motor. When electromagnetic compatibility is important, a shielded motor cable can extend up to 150 m; in installations with lower electrical noise, an unshielded cable run of up to 300 m is permitted. The drive’s logic circuits are protected against signal overvoltage because the digital inputs are rated for a maximum of 28 V DC. These inputs can receive switching signals from external controls, sensors, and interlocks used in building automation systems.