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Variable Frequency Drives (VFDs) are a type of motor controller that drive electric motors by causing a variation in the voltage and frequency, which is supplied to the electric motors. Variable Frequency Drives may at times be referred to as adjustable speed drives, variable speed drives, adjustable frequency drives, inverters, AC drives, or Microdrives. Even though Variable Frequency Drives are essential, they present some dangers if not operated and maintained the right way. It’s, therefore, necessary to have essential knowledge about their safe operation and maintenance to avoid the occurrence of any ugly incidents at the workplace.
Frequency affects the motor’s speed directly meaning that the speed of the motor is determined by how fast the frequency is. If a certain application does not need an electric motor to reach its full speed, the Variable Frequency Drive can be utilized to alter the voltage and frequency in such a way that it levels to the requirement of the load of the motor. Every time that the speed requirements of the application’s motor change, the Variable Frequency Drive can just increase or decrease the speed of the motor to fit the speed requirement.
In a Variable Frequency Drive, the first stage is the converter, which comprises of six diodes. These diodes resemble the check valves, which are used in a plumbing system and allow current flow in a specific direction. In most Variable Frequency Drives, there are usually three diodes. These produce negative and positive pulses that add up to six current pulses in number.
Variable Frequency Drives usage in various machines continues to increase daily as the demand for better automation and energy efficient machines rises. The application of the drives ranges from small machine tools to large-scale machinery used in manufacturing plants. In all places where VFDs are used, the need for enhanced functionality that is is high, specifically in places where there is great demand for machines that can handle complex automation tasks.
Just like most devices that use electricity to power them, Variable Frequency Drives can result in some hazards due to poor maintenance and lack of observation of safety measures. If poorly maintained, VFDs can lead to insulation breakdown and heating in a number of applications. These can result when transistors are switching at a fast rate. When this heat is produced at a place where there are flammable gases, there is a high chance that a fire will result. This may result in the loss of property and lives, and the company may have to consider replacing equipment, compensating workers and looking for replacements for very important members of staff.
To avoid the risks involved with the use of Variable Frequency Drives, one must know the fundamentals. Safety measures may vary with the various applications since they don’t all resemble each other. However, there are some general safety measures, which apply to all of them. Some of these safety measures include keeping the VFD clean, making sure that it’s always dry and ensuring that the connections are always tight.
Most Variable Frequency Drives usually have side vents, which are there to ensure that there is cooling airflow. These side vents make the Variable Frequency Drive susceptible to dust, and can easily reduce the effectiveness of heat circulation fans as well as heat sinks. Thus, the dust may cause a malfunction when there is moisture absorption. Therefore, the drives should be cleaned from time to time.
The VFD if subjected to moisture build-up can cause the circuit board to corrode, leading to malfunction. To keep it dry, a space heater that is thermostatically controlled should be introduced if there are high chances of air condensation and the side vents should always be functioning properly.
As obvious as it is, not everyone remembers to check the connections. It’s important to ensure that screws are not too tight or loose since they may ruin connections causing electric shocks and other electrical hazards. Also, one should inspect the DC capacitors, keep track of the voltage and monitor the temperatures of the heat-sink.
Every person who works where Variable Frequency Drives are used should be well educated on the safety measures involved when operating VFDs. If you’re an employer, who is interested in expanding the knowledge that your employees have on Variable Frequency Drives as well as educating them on how they can stay safe when operating them, consider enrolling them for training on Variable Frequency Drives through NTT Training. To learn more about the seminar, don’t hesitate to contact us at any time.
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