what is the advantages and disadvantages of variable speed drives

You want to know first why variable drives are used ... I can point some advantages and disadvantages ... Speed control can be possible in both AC and DC machines by varying the firing angle, regeneration can be possible if angle more than 90 and emf is negative, better regulations, fast controls, speed above n below rated are possible energy effecient, dyamic respnse ..... In AC there are 4 to 5 menthods where we can adjust speed in stator voltage control we can increase the volatge beyond the rated , in pure frequency control below rated frequency saturation of core, in DC we can increase volage above rated ,etc..initial drive cost maintenance... Etc and main disadvantage is.harmonics generation but this can be eliminated... To explain in details I can't post here it require from starting ...let me know for more Thanks read less

Advantages & Disadvantages :- Adjustable Speed Drives have a number of advantages and disadvantages compared to other types of variable speed controls including: Advantages Energy Savings Improved Process Control Reduced Voltage Starting Lower System Maintenance Bypass Capability Multi-motor Control Disadvantages:- Initial Cost Motor Heating at low Speeds Maintenance Output Harmonics Induced Power Line Harmonics read less

A variable speed drive controls motor speed and torque by varying the motor input voltage and frequency. A very close match between motor speed and the output requirements of the machine it is driving may therefore be achieved. Variable Speed drives offer the user a number of advantages including: Energy savings Elimination of expensive mechanical drive components Increased motor longevity Reduced power line disturbances Reduced risk of motor damage during start up and stop The energy savings alone can often justify the cost of purchase and installation of a VSD. Unfortunately, most of these advantages may be compromised by poor installation, operation and maintenance practice. To apply a VSD correctly a basic understanding of the following is required: Safe working practices. Understand the place for a VSD in the overall system. How to identify the best VSD for the job. Correct installation and set-up. The VSD user interface. Fault and warning action and processing. Preventative maintenance. And this information needs to be maintained and updated as new industry standards and equipment enter the market. Safe working practice training should be a given in any business but the rest can be a challenge for the engineer busy with every other issue they are faced with on a daily basis. Most variable speed drive manufacturers provide training literature and even courses on the best practice for their equipment. However, given the demands on an engineer’s time and the unique challenges faced in particular applications a ready reference tool, a guide and constant companion is often best. At Quantum-Controls we have created such a guide based on fifteen videos covering installation, quick start up, macros and fault diagnosis. All presented by an engineer not an actor or salesman. The disadvantages of variable speed drives include: Initial Drive Cost - Motor Heating at low Speeds - Maintenance - Induced Power Line Harmonics However, these disadvantages can be mitigated to an extent by correct application and maintenance as outlined above. A simple calculation of energy savings versus the cost of the drive, its installation and maintenance can guide the decision to install a drive (or not). read less

You want to know first why variable drives are used ... I can point some advantages and disadvantages ... Speed control can be possible in both AC and DC machines by varying the firing angle, regeneration can be possible if angle more than 90 and emf is negative, better regulations, fast controls, speed above n below rated are possible energy effecient, dyamic respnse ..... In AC there are 4 to 5 menthods where we can adjust speed in stator voltage control we can increase the volatge beyond the rated , in pure frequency control below rated frequency saturation of core, in DC we can increase volage above rated ,etc..initial drive cost maintenance... Etc and main disadvantage is.harmonics generation but this can be eliminated... To explain in details I can't post here it require from starting ...let me know for more Thanks read less

A variable speed drive controls motor speed and torque by varying the motor input voltage and frequency. A very close match between motor speed and the output requirements of the machine it is driving may therefore be achieved. Variable Speed drives offer the user a number of advantages including: Energy savings Elimination of expensive mechanical drive components Increased motor longevity Reduced power line disturbances Reduced risk of motor damage during start up and stop read less

A variable speed drive controls motor speed and torque by varying the motor input voltage and frequency. A very close match between motor speed and the output requirements of the machine it is driving may therefore be achieved. Variable Speed drives offer the user a number of advantages including: Energy savings Elimination of expensive mechanical drive components Increased motor longevity Reduced power line disturbances Reduced risk of motor damage during start up and stop Disadvantages : Need proper installation hence most of the advantages shall be compromised Proper Maintenance is required read less