Custom Sheet Metal Fabrication: What You Should Know

Posted on: 19 December 2013

Motors with electro-mechanical starts do not create worthwhile harmonics. When the adjustable speed drive is used to power the motor, the circuitry to drive does not take the current in a sinusoidal manner. This can affect other equipment attached to the transformer. Harmonics are currents and volts that consist of multiples of 60 Hz. The power generated cannot be used and takes up the electrical capacity of the motor. The system that has a lot of harmonics will eventually break down as a result of the defect. The harmonic filter is used to reduce the current gulps that cause this problem. The harmonic filter is not usually able to smooth the waveform. However, it is able to minimize the worst harmonics. The filter is made out of various capacitors, resistors and inductors that are designed to deflect currents to allow them to disperse into the ground. The capacitor is an electrical component that stores energy electrostatically. The resistor is a two-terminal component that uses electrical resistance as a part of a circuit. The ratio of the voltage applied to the resistor to the intensity of the current is called the resistance. An inductor is a passive two-terminal component that resists alterations in the electric current. One of the advantages of harmonics is that the networks can have a high power factor and greater voltage stability. The power factor is the ratio of real power flowing to a load to the power of the circuit. Voltage stability refers to when a system is able to maintain a voltage to serve the particular load. The harmonic filter allows for resonance problems to be avoided and allows for the amplification of electrical disturbances. Amplification refers to the act of increasing the power of the electrical signal. When a network is cleaner, this places less strain on the motor and wiring. This allows for the equipment to have a much longer lifespan, which means that the network will have less costs for replacing equipment. The harmonic filters are meant to work with any 6-pulse and PWM drive on standard NEMA design motors. When trying to decide whether a harmonic filter should be used by a specific motor, it is a good idea to contact the manufacturer of the motor to verify. Generally, the harmonic filter will not need any special adjustments to attach them to the drive. However, like with the motor, it is a good idea to contact the manufacturer to determine if the harmonics need adjustments. Real or true power refers to the power that is used to perform actual work on a motor. Motor owners are often concerned with how the harmonic filter can improve the power factor. The flow of reactive currents do consume power as they pass through the resistance within the power system, causing the overall efficiency to be reduced. Harmonic filters can be used on bypass applications as long as the series inductor does not cause too much of a line voltage drop. Whether the harmonic system will cause these problems or not will depend on the components and configuration. The harmonic filters are designed specifically for application to a single drive. However, if the harmonic filter is sized properly, it can be used for multiple engines. However, the filter will need to be sized properly to prevent damage to the engine. Some systems have a harmonic limit requirement. For these systems, it will be important to communicate with the manufacturer of the harmonic filter and also the individual responsible for designing the facility to make sure that an analysis is performed of the base line value.