Harmonic Mitigating Transformer
Product Overview & Application
Harmonic Mitigating Transformers (HMT's) are specially designed for non-linear loads which draw significant amounts of harmonic current. While K-factor rated transformers are simply designed to handle the additional losses of supplying non-linear loads, HMT's actually minimize the voltage distortion and power losses that result from harmonic load currents.
General purpose and K-Factor rated transformers have a high impedance to the flow of harmonic currents, and therefore, when harmonic currents are drawn by the load, significant voltage distortion can be measured on the transformer secondary. This voltage distortion leads to higher losses on nearly all devices supplied by these transformer, and depending on the amount of non-linear loading, can exceed the maximum 5% THD (IEEE 519).
Harmonic Mitigating Transformers provide a low impedance path to these harmonic currents by a combination of phase shifting and zero sequence flux cancelation:
- Zero Sequence Flux Cancelation: The secondary windings of HMTs are specially designed such that zero sequence fluxes (3rd, 9th, 15th current harmonics) cancel out without being drawn from the primary and circulating in the primary delta winding. The flux cancelation provides a low impedance path for the zero sequence harmonic currents, which reduces the voltage distortion significantly. Furthermore, with no zero sequence circulating in the primary delta winding, the losses within the transformer are reduced significantly.
- Phase Shifting: The non triplean harmonics (5th, 7th, 11th, 13th, 17th & 19th) are mitigated by introducing of phase shifts on the secondary side of the HMT. Depending on the arrangement selected single, dual or triple output), specific harmonic currents can be mitigated without coupling them to the primary windings.
Product Specification
Capacity | 15 to 1,000kVA Three Phase |
Voltage Class | 600V |
Cooling | Self Cooled (ANN) |
Frequency | 60Hz (50/60Hz Optional) |
Conductors | Copper (Cu) or Aluminum (Al) Windings |
Insulation System | 220°C (150°C rise) (optional 115°C or 80°C rise available) |
Impregnation | Polyester Resin Dipped and Baked |
Efficiency |
Meets North American Energy Efficiency Standards:
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K-Factor | Suitable for non-sinusoidal current load with a K-factor not to exceed 4 (K9, K13, K20 Optional) |
Primary Taps | Typically +/-2 x 2.5% taps (refer to dry type distribution transformer catalogue) |
Configuration | Single, Dual or Triple output |
Sound Level | Meets NEMA ST-20 |
Enclosure Type | Type 1 or 3R Indoor (refer to catalog) |
Enclosure Finish | ANSI/ASA 61 Grey |
Warranty | 12 Months (See Warranty and Limitations) |
Quality System | ISO 9001:2015 Quality Management System |
Certifications |
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Reference Standards |
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Optional Features & Accessories |
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