Product Description:

The VLT 3504 is an AC variable frequency drive manufactured by Danfoss for the VLT 3000 Variable Speed Drives series. Installed between the mains supply and a three-phase induction motor, the unit modulates output frequency and voltage so plant controllers can match motor speed to changing load requirements. This control can reduce energy losses and mechanical stress on pumps, fans, and conveyors in industrial automation systems.

During operation, the drive converts input power with an efficiency of 0.96, so only four percent of the supplied energy is lost as heat. The supply can be disconnected and reenergized up to twice per minute, a switching limit that avoids capacitor stress during frequent stop-start cycles. Cabinet planning is aided by the housing, which spans 11.18 in across the front panel and projects 7.01 in into the enclosure. Motor and line conductors may be terminated on lugs that accommodate wire up to 12 AWG, and a dedicated protective earth stud provides grounding protection. The output transistors are rated for unlimited switching events. Integrated electronic thermal protection works with a DIN 44081 thermistor to prevent overheating. Built-in short-circuit protection isolates the inverter during fault conditions.

In system layouts where the motor is remote from the drive, a shielded cable up to 1000 ft long can be used without degrading control accuracy. The bare chassis version weighs 16 lb, making it suitable for panel mounting, while the NEMA 1 enclosure weighs 18 lb and the sealed NEMA 12 housing weighs 24 lb for use in areas exposed to dust and splashing water. All versions tolerate continuous vibration levels of 0.7 g, which suits typical wall-mounted electrical equipment used near compressors, presses, and other sources of low-frequency oscillation.