Differences Between Technologies
Starting motors on conveyor belts can lead to excessive belt tension and rapid accelerations. In fact, AC motors often exceed 250% of rated torque during startup. Moreover, motor current can reach up to 600% of rated load during acceleration. Ultimately, high current accumulates heat that can drastically shorten motor lifespan. With empty or partially loaded belts, acceleration rates are even faster, and excessive shock loads with high torque during startup can exceed belt design limits. Belts can be damaged, splices can break, not to mention the potential for material spillage.
In any case, whether belts are empty or full, the threat of profit loss due to downtime and belt breakage costs persists.
SOFT STARTERS OR VARIABLE FREQUENCY DRIVES
Soft Starters
Soft starters gradually accelerate the motor to minimize mechanical shocks and peak electrical demand. They are ideal for applications requiring constant operation at full speed. Due to their torque characteristics, they are suitable for conveyors with light loads that start ten times or fewer per hour. They are a straightforward substitute for direct online starters to prevent damage during startup and shutdown.
Advantages of Soft Starters
Soft starters are smaller and cheaper than variable frequency drives (VFDs) and require less panel space. With fewer internal and external components, maintenance costs are usually lower. They protect the motor by minimizing startup current and reducing motors tension, switching to line power during operating cycles.
Additionally, controlling startup current can reduce penalties for demand peaks, resulting in lower energy bills for utilities. Moreover, by reducing mechanical shocks, they contribute to extending equipment lifespan.
Variable Speed Drives (VSDs)
VSDs control motor speed and torque by varying and regulating input frequency and voltage. Their dynamic torque control allows precise speed control of the conveyor regardless of load variations. They provide constant torque at zero speed to manage heavily loaded conveyors from startup.
Advantages of VSDs
VSDs provide better control of constant torque to reduce mechanical shocks and power demands when starting large motors. Since VSDs offer variable speed control, they can adapt to exact speed requirements of the conveyor system. This improves processes, saves energy, and extends the lifespan of conveyor equipment.
Conclusion:
Soft starter applications are best suited for full speed operation with low or medium starting torque and light load. They reduce system wear and damage and help control starting currents and power control applications.
VSDs adapt to speed control demands during operation mode, single-phase use, and applications with high starting torque. They provide continuous feedback for critical position control and constant torque at zero speed. An additional advantage is the reduction of mechanical wear and damage to the conveyor system.
Variable Speed Drives or Soft Starters in Conveyor Belt Startup.
