The Omniverter DHF raises the bar in harmonic filtering. Dynamic voltage control with smart sensing makes filtering simple and efficient. It has automatic impedance regulation using micro processor controls and responds instantly to variations in loads.
The DHF is voltage controlled, therefore no current transfomers are needed. The DHF removes the need for detailed site harmonic measurements and complex calculations.
The DHF will correct harmonics 5th, 7th and 11th or above, whether they are created by equipment within the customer’s premises and/or from those created elsewhere and transmitted via the electrical utility supply.
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The Omniverter DHF has three unique features to consider when choosing an appropriate solution:
- When the THDv is above 8%, the DHF is the option, as Active Harmonic Filters are not designed for THDv higher than 8%.
- Overload capability. Automatic impedance regulation and instant response to variations in load are features that minimize the risk of filter overload.
- The DHF will correct harmonics 5th, 7th and 11th or above, whether they are created by equipment within the customer's premises and/or from those generated elsewhere and transmitted via the electrical utility supply.
A harmonic distortion is a form of pollution in an electrical system. A harmonic voltage or current waveform is a sinusoidal wave whose frequency is an integer multiple of the fundamental frequency. For example, the 3rd order harmonic frequency for a 60Hz system is 180Hz,5th is 300Hz, 11th is 660Hz, etc.
The waveformdistortion is expressed in Total Harmonic Distortion as a percentage. THD or THDi is a measurement of the harmonic distortion present and is defined as the ratio of the sum of the power of all the harmonic components to the power of the fundamental frequency.
Harmonic generation are generally found in saturated and power electronic devices. For example, a transformer and a motor create harmonics when over-fluxed or saturated. Power electronics (non-linearloads) also produce harmonic frequencies, loads like rectifiers or variable frequency drives.
The following scenarios are some of the failures that are common when the THD is above the recommended levels:
- Degradation of motor bearings
- Overload and overheating of transformers
- Circuit breakers and fuses may fail for unknown reasons
- Interference with communication, sensors and automation control equipment.
Harmonics can be produced in a plant and/or it may be transmitted upstream from the utility supply. In practice, it is difficult to determine who is responsible for the harmonic distortion as it depends both on the utility supply (impedance) and the customer (load current).Therefore, detailed analysis is required to determine the source of distortion. Power Quality Analyzers installed permanently are advisable to measure and monitor the THD levels.