Variable Frequency Drives
Standard induction motors rotate at fixed speeds based on the voltage and frequency of the source of incoming power. The motor always runs at its peak load because the speed of the motor is fixed. However, because the motor rarely needs to run a peak load, energy is wasted, and you will end up with a more expensive motor than you expected.
Also, when starting an electric motor, the inrush of power leads takes the motor from idle to 100% power in seconds. That sudden inrush damages the motor leading to frequent repairs and perhaps replacement. In short, the lifespan of an expensive piece of equipment is shortened.
There is a solution to these problems: Variable Frequency Drives. Some of the main advantages of using a variable frequency drive (VFD) to control your motor are:
- Startup: a motor controlled by a VFD uses a very low frequency and smaller amounts of voltage to increase the speed of the motor gradually. This smooth startup saves unnecessary power usage and eliminates the jarring startup inrush, ensuring the motor runs smoothly.
- Control: the flow of current and speed of the motor are controlled by the VFD. A VFD also adjusts the speed of thermal and mechanical pressure on the electric motor or its belts, varying temperature, and revolving speed.
- Stress: VFDs minimizes any mechanical and electrical stress by using a lower power factor and reducing some vibration problems.
- Energy Savings: The energy saved by using a VFD is by far the largest benefit. The cost savings can be enormous; over a short amount of time, a VFD actually pays for itself. Even reducing the speed of the motor a little directly affects the power consumption.
For example, A VFD running at 50% uses 12.5% of the energy normally needed to run at 100%. At 80%, the VFD only uses 55% of the energy used at 100% operating speed. The amount of power savings adds up over time, which saves you a lot of money!
ApplicationsVFDs are used in applications where:
- Operational speed control is a necessity
- Custom speed control is a requirement
- Energy savings is an objective
- Emerson Control Techniques
- Yaskawa Electric