Littelfuse Solutions for Industrial Motor Drives and Soft Starters
Variable Frequency Drives (VFDs) and soft starters are used in various industrial applications to increase motor life and improve energy efficiency by reducing the inrush currents and limiting the torque. VFDs and soft starters work on similar principles but have different architectures and are used in different applications.
| Variable Frequency Drives | Soft Starters |
| Controls AC motor speed and torque by varying motor input voltage and frequency | Offers smooth start and stop operation for a motor |
| Can be programmed to vary the speed of the motor based on factors such as flow and pressure. | Gets bypassed by a contactor overload circuit as motor reaches its full speed |
| Complete control over motor speed can be achieved | Initial cost is lower than a variable frequency drive |
| Performance more important than cost and size | Effectively reduces inrush current during motor start |
| Energy saving is principal advantage | No harmonics are generated |
| Examples of applications: elevators, escalators, crushers, mixers. | Examples of applications: conveyors, pumps and other belt-driven applications |
Littelfuse offers a wide array of circuit protection and power semiconductor solutions for VFDs and soft starters.
Littelfuse Solutions for Variable Frequency Drives
Circuit Protection Solutions
Over-Current Protection
Littelfuse offers industrial power & UL class fuses for higher interrupt ratings (JLS, JLLS, LDC, L70QS) as well as electronic fuses (606, 504, 505). Littelfuse also offers semiconductor fuses (PSR) specially designed for protection of power semiconductor devices such as diodes, triacs, IGBTs, SCRs, MOSFETs and other solid-state devices that are typically designed into power conversion and power conditioning equipment.
Over-Voltage Protection
Littelfuse offers varistors (TMOV) to protect against damage due to lightning-induced surges or harmonic voltage disruptions from the power line. For secondary over-voltage protection, especially for high-power line voltage applications of 600V or higher, Littelfuse offers the AK3-380C TVS diode.
Power Semiconductor Solutions
Littelfuse offers a wide range of rectifier modules (MDD, VUO, VUB) needed for the rectification circuitry, and the MIXA/MIXG IGBT modules for high-frequency switching.
Littelfuse Solutions for Soft Starters
Circuit Protection Solutions
Littelfuse offers a wide range of over-current and over-voltage protection solutions for soft starters.
Over-Current Protection
Littelfuse offers fuses (L50QS, L70QS, JLS, JLLS) for supplementary protection of semiconductor devices such as SCRs, diodes and IGBTs.
Over-Voltage Protection
Littelfuse offers varistors (TMOV) to protect against damage due to lightning-induced surges or harmonic voltage disruptions from the power line.
Power Semiconductor Solutions
Littelfuse offers both discrete SCRs (N Capsule series) as well as SCR modules (MCC) used in soft starters to control the supply voltage to the motor.
