Adjustable speed drives (ASDs), also known as variable speed drives (VSDs), are used to describe devices that help control the speed of machinery. They are used in mechanical equipment that is driven by a motor.
These drives provide precise motor control so that the motor speed can be increased and decreased and maintained at the desired speed. Though, the motor can be operated without the help of any drive.
1.Controlled starting current:
Typically, when an AC motor is started "across the line," it takes about seven to eight times to start the motor and load.
By using an adjustable speed drive, the starting current is greatly reduced, thereby extending the life of the AC motor. The benefit is reduced motor wear, which extends motor life and reduces motor rewind.
2.Controlled stops:
Controlled stops help minimize product loss due to breakage from process shock or mechanical wear.
3.Reversible operation:
Using an adjustable speed drive eliminates the need for a reversible starter because the motor's output phase can be changed electronically without mechanical equipment. Getting rid of reversible starters eliminates their maintenance costs and reduces panel space.
4.Lower starting power requirements:
The power required to start an AC motor across the line is much higher than an adjustable speed drive. This is accurate only at the start because the power to run the motor under load is equal regardless of whether the motor is fixed or variable speed.
5.Adjustable operating speed:
Using an adjustable speed drive allows processes to be optimized and changes to be made in the process. It also allows for start-up at lower speeds and allows for remote adjustment of speeds via programmable controllers or process controllers.
6.Energy Savings:
Centrifugal fans and pumps running with adjustable speed drives have reduced loads due to energy consumption. If the fan speed is cut in half, the horsepower required to run the fan is reduced by one-eighth.
Energy savings can be associated with a return on investment (ROI) of less than 2 years.
7.Eliminate mechanical drive components:
Using an adjustable speed drive eliminates the need for expensive mechanical drive components such as gearboxes. Because the drive can operate at infinitely variable speeds, it can deliver the low or high speeds required by the load without the need for a variable speed device between the motor and the load.
This eliminates maintenance costs and reduces floor space requirements.
8.Adjustable Torque Limit:
Using an adjustable speed drive protects machinery from damage and protects the process because the amount of torque applied to the load by the motor can be precisely controlled.
9.Reduce power line interference:
Starting AC motors over the line and the demand for starting current can put a significant drain on the power distribution system connected to the motor.
Often, supply voltage dips can cause sensitive equipment connected to similar distribution systems to trip. Products such as computers, sensors, proximity switches, and contractors are sensitive to voltage and can drop out when huge AC motors are started nearby. The use of adjustable speed drives eliminates such voltage dips.