RHF- Passive Harmonic Filters by REVCON
Overview of RHF-Passive Harmonic Filters
Our compact and cost-effective active harmonic filters are mainly used in:
General Industry
Data center
Water treatment
Oil & Gas
Buildings
What is a Passive Harmonic Filter?
In theory, all power sources have a sinusoidal current waveform that is pure. However, a true waveform is quite different. Most loads or sources are nonlinear in nature, such as the diode input bridge of a 6-pulse drive. A passive harmonic filter is a device used to counteract this nonlinear load or distortion. It does so by filtering out any unwanted frequencies at the source.
Passive harmonic filters play a key role in VFDs by improving the power quality and increasing the reliability of the equipment. The end result is a reduction in power bills and a more efficient operation of VFDs.
Harmonic Distortion – A Growing Challenge
What Are Harmonics and How Do They Affect Systems?
Most power systems provide a nonlinear load in practice, leading to distortion of the mains voltage. This is denoted as Total Harmonic Distortion (THD or THDi) which is calculated by evaluating frequencies between the 2nd to the 40th or 50th harmonic. This voltage distortion has a number of negative effects and thus necessitates the use of passive harmonic filters.
Negative Effects of Harmonic Distortion:
Transformer and Capacitor Bank Overloads - Harmonic distortions can cause the transformers to overheat. Similarly, they can also lead to a capacitor bank overload by impedance, resonance, excessive heating and voltage stress.
Increased Energy Costs and Equipment Downtime - To function effectively despite the distortion, the equipment can take up excess energy, leading to higher expenses and further heating the equipment, ending up in increased downtime.
Vibration Damage and Reduced Equipment Lifespan - Harmonic distortion can also lead to the equipment vibrating excessively, causing extensive damage if left unchecked and reducing the equipment’s overall lifespan.
RHF-5P and RHF-8P – Double-Stage Passive Harmonic Filters
Why Choose RHF-5P and RHF-8P Filters?
The RHF-5P and RHF-8P are double-stage passive harmonic filters that can reduce the total harmonic distortion (THDi) of VFDs and other non-linear loads to below 5%. This is verified in real-world settings where imbalance and pre-distortion are taken into account. Moreover, it can be simply connected in line to any load and is compatible with a standard, 6-pulse VFD.
Key Features of RHF-Passive Filters:
- To prevent excessive heating, these passive harmonic filters offer forced air cooling in IP20 enclosures designed for protection against solid objects and dust. This allows our passive harmonic filters to be much more compact in size than our competitors.
- Tested for application in real-world scenarios and not just simulations, our passive harmonic filters provide smooth dampening of all harmonics up to the 200th order.
- Our passive harmonic filter products also feature a patented double-stage filter circuit, leading to maximum efficiency. It can reduce a THDi of 35% down to 3%.
Performance and Efficiency of RHF-Passive Filters
Improved Power Efficiency:
Compared to other passive harmonic filters, REVCON’s models achieve a very high power efficiency of 99.5%. This brings the power losses down by almost 75% when compared to other solutions that are used to tackle power loss.
Ensuring Full Drive Power:
REVCON’s passive harmonic filter ensures a 100% DC-Bus voltage at 100% drive load. Therefore, it eliminates the need for de-rating the drive. When compared to other simple passive harmonic filters, the REVCON passive filter offers a 7% increase in power ratings. It also means that multiple drives can be connected to and operated with one filter.
Design and Configuration Options
Available Configurations:
The RHF-5P and RHF-8P passive harmonic filters are available for all inverter sizes, with a range of 4kW up to 800kW. It also has a capacitor disconnect option, a standard in passive harmonic filters.
Customization Options:
REVCON passive harmonic filters are customizable for almost all types of VFDs, provided a 6-pulse rectifier is used at the input.
Motors with IE3 efficiency can be combined with a VFD and passive harmonic filter for heavy-duty and standard applications. In case the motor has a lower efficiency rating, the harmonic filter’s rating should be high enough to compensate.
Advantages of Double-Stage Filter Technology
As mentioned before, REVCON’s passive harmonic filter employs a double-stage filter technology, which has numerous benefits.
Three Key Benefits of Double-Stage Filters:
1. Superior Performance: Designed for stated use in its field and not for a simulated condition, these passive harmonic filters are highly effective and provide smooth dampening up to the 200th harmonic order.
2. Full Power Availability: Since they offer 100% DC voltage and 100% drive load, there is no need to de-rate the passive harmonic filter before using it with VFDs.
3. High Efficiency: Compared to simple harmonic filters that employ RC circuits, the REVCON passive harmonic filters guarantee 70% less power loss. This is specifically true for cases where the total harmonic distortion (THDi) has to be below 5%.
RHF Sizing and Installation Guidelines
How to Choose the Right RHF Filter for Your Needs:
The type code of the RHF passive harmonic filter is the easiest way to shortlist the best filter for your requirements. The most important step is in identifying the nominal motor power. This is found by examining specific type codes. For instance, if the type code is RHF-5P 280-400-50-20-C, then the number 280 here denotes the nominal motor power compatible with this filter, which in this case is 280 kW.
However, please note that this is applicable only for highly efficient IE3 motors. For motors with low efficiency, a passive harmonic filter with a higher rating is needed.
Installation Tips:
After selection, it is also important to understand some nuances prior to installation. For instance, the nominal output current of a VFD is typically higher than the input current of the RHF passive harmonic filter. This is mainly because the VFD has to provide the reactive power to operate the motor. However, if you choose a filter dimension based on the VFD’s nominal output current, you will end up with a filter that is too oversized for the operation.
Recommended Use Cases for RHF-Passive Filters
Ideal Applications Include:
- Pumps, Compressors, and Ventilation Systems: Passive harmonic filters protect precious equipment, provide better power quality and lower the overall energy costs of operation.
- Systems with High Ratios of VFDs and Nonlinear Loads: The main purpose here is to mitigate the harmonic distortion from this arrangement.
- Continuous-Running Applications Requiring Harmonic Mitigation: In this case, even slight distortions can cause the system to stop functioning.
Compliance with Industry Standards
Meeting IEEE 519-2014 Standards:
The IEEE 519-2014 is an international standard for all electrical equipment. For a passive harmonic filter to qualify for this rating, it must reduce the total harmonic distortion (THDi) to 8%. The RHF models surpass this by reducing THDi below 5%. This covers non-linear loads and VFDs where imbalance and pre-distortion are at play.
Contact Us for Customized Solutions
Need Help Selecting the Right Filter?
To find out the perfect passive harmonic filter for your specific requirements, contact us at ADM Engineering Inc. today at 1-877-236-8337 and our experts will guide you through different parameters such as VFD compatibility, performance and more.
Further information on individual sizes are listed in the datasheets. Please select your parameter.
If you can´t find your preferred filter above, please don´t hesitate to contact us. Due to our wide portfolio and long experience we are able to offer customized solutions for any application.
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