Page 63 - TEXtalks October/November 2021

63

Guide to Variable Speed

Drive (VSD) Applications

for Spinning

Imtiaz Rastgar
Rastgar & Co, Islamabad

Maintenance and
Why using a VSD can help you save money in Textile Service cost
Mill? Investment Regulated speed
compressors can
For all section of spinning mills (From Ring to Auto efficiently and reliably
Cone Section, Back Process and Doubling Section) CompAir handle the varying air
demand found in most
variable
in Pakistan, a combination of fixed and variable speed L-RS plant air systems. The
speed drive Air Compressor will yield maximum compressor annual cost of
operating
ownership can be
benefits in terms of productivity, Energy and costs at 70% load significantly reduced
savings. The Variable Speed compressor can Energy using regulated speed
technology.
efficiently handle the varying air demand by varying Costs
motor speed according to plant’s air requirement,
there by cutting down off-load hours running cost to A trio of justifications for using VSDs in
almost negligible. Compressors
1. Less Energy Use: Typically, a fifth of an average
Top three reasons to select a VSD factory’s electricity bill can be attributed to the
1. Reasons to Select A VSD: One of industry’s production of com-pressed air. In short, the major
principal concerns with soft starters is the limited benefit of using a VSD in these applications is that it
slow speed control they demonstrate between automatically adjusts its motor speed to the air
starting and stopping. In contrast, a VSD) can deliver demand.
precise speed control, including during start-up and
stopping. In short, VSDs provide continuous and 2. Safety and reliability: Modern VSDs offer numer-
completely adjustable speed whenever required, ous safety features, like protection against power
from starting to stopping, for hours at a time. surges and short circuits, as well as STO (safety
torque off) functionality. By adopting a drive offering
2. When energy consumption must be minimized: such features, compressor OEMs can avoid the
Energy savings are a headline benefit of VSDs, and requirement for certain electrical components that
the explanation for this characteristic lies with speed include motor circuit breakers and contactors, thus
control. Using a VSD serves to actually reduce the reducing costs.
motor speed. The upshot of this effect is that fewer
amps are drawn by the motor. In turn, there is less 3. More Stable Pressure: A VSD in a compressor
energy consumption, resulting in lower energy bills. system can stabilise the up and down pressure in the
pipe network, potentially even eliminating pressure
3. When maintenance costs need to be reduced: fluctuations altogether. The upshot of this capability is
Another major advantage associated with the use of that all compressors operating in the system can run
VSDs is that gradual acceleration of the motor from at the lowest pressure needed to meet production
standstill promotes extended service life and reduced requirements, and reduce the power loss caused by
maintenance costs. In comparison, if not using a the fluctuation of upward pressure. Additionally, the
VSD, the motor will start instantly with a large current, potential for system leaks is minimized thanks to the
which can be highly detrimental to motor longevity. lower system pressure.

October/November 2021