In the rolling mill, the roller table is an essential part of production. It is used for converting material shape, where material size (thickness) is reduced as per the desired shape. These motor-driven rollers are installed to feed material in the mill and are designed to operate quickly in a forward/reverse direction.

The same is achieved by reversing the motor direction through R-DOL (Reverse

-Direct Online Starting) contactor logic.

This results in a very heavy ingress current up to 15 times of motor FLC (full-load current) which causes electrical and mechanical jerks. This further leads to electrical issues like failure of contactors, starters, motor winding, and mechanical issues like chain slippage, early wear and tear of belts and sometimes failure of gearbox etc. which results in increased cost of maintenance and downtime.

A team from Drives business of L&T Electrical & Automation studied the entire operation and observed that mechanical jerks were caused due to reversing the motor polarity. This happened abruptly with the contactor switching in forward and reverse direction.

The FX2000 AC drive-based solution was implemented which eliminated the existing starter or kept it in bypass and operated the Roller motor. The solution helped to reduce electrical jerks by almost 90%. While a normal starter takes 15 times motor FLC during phase reversal, the FX2000 VFD takes only 1.5 to 2 times current. Further, the VFD ensures sufficient holding torque in the motor during break operation to prevent any slippage.

The Drive operates at a very precise acceleration and deceleration time. The frequency-controlled operation with VFD and smooth ramp-up to full speed ensures the elimination of all electrical/mechanical issues associated with Reverse- Direct Online Starting (RDOL) without increasing the cycle time.

• Improved assets life
• Reduced down-time
• Reduced maintenance cost

As consumers of electricity, we all need an uninterrupted power supply to continuously run the operations of buildings, industries and other infrastructure. At the same time, we cannot ignore the quality of power which is impacted by the use of switching electronic devices like variable speed drives (VFDs), uninterruptible power supplies (UPS), switched-mode power supplies (SMPS), light-emitting diode (LEDs), etc. The poor quality of power leads to premature failure or degrades the performance of equipment and has a negative impact on the overall electrical system.

E&A’s Power Quality Solution helps run all your electrical systems efficiently and reliably by improving the quality of power in its distribution network.

Consult with the E&A team to know how you can consistently maintain Unity True-Power Factor and mitigate current harmonics as per IEEE 519 or about a special solution for high voltage harmonics.

E&A’s offerings include Type Tested APFC Panel as per IEC 61439 & IEC 61921, a wide range of Active Harmonic Filters, Hybrid Harmonic Filters, and many others.

Every energy unit is charged, and it is thus essential to know where it is being used. E&A helps you to measure your energy spend.

Know more about how our SmartComm EMS

(Energy Management Software) helps you to monitor energy consumption in real-time, take corrective actions in areas of energy wastage and improve energy efficiency.