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Drive Isolation Transformer

Product Overview & Application


Drive Isolation Transformers are designed for supplying power to SCR (Silicon Control Rectifier) motor drives which provide convenient variable speed motor control and can save on energy. Unfortunately, the drawback of these variable frequency drives (VFD) is that they produce harmonic voltage distortion and draw harmonic currents from the source which can be damaging both to the transformer supplying the power, and the other equipment that is connected to that supply.

A Drive Isolation Transformer (DIT) is designed specifically to supply power to VFDs. The isolation between the primary and secondary provides electrical isolation between the supply and the load. The transformer core is designed to handle the harmonic voltage without saturating, and the coils are braced to handle the mechanical forces that are introduced due to these harmonic currents. The coils are also designed to mitigate the impact of the harmonic currents. The winding conductors are selected and designed to keep eddy and stray losses to a minimum and the sufficient cooling is provided to dissipate the additional heat generated by the harmonic current.

Features & Benefits

  • Core and coil assemblies are mounted on neoprene isolation pads to reduce noise
  • Electrical Isolation between the supply and load minimizes feedback of noise generated by SCR voltage spikes to the supply.
  • Thermal sensors embedded in LV coil and wired to terminal blocks can be used for remote monitoring and protection. Bolted coil terminations suitable for copper or aluminum cables
  • Front & back covers are easily removable for service
  • Transformer core is constructed of high quality grain oriented silicon steel and operated well below the materials saturation levels in order to handle th impact of harmonic voltage and current.
  • Suitable for non-sinusoidal load currents with a K factor of 4 (higher K factors are optional).
  • Extra bracing is provided to withstand the mechanical stresses associated with SCR drives
  • Neutral terminal rated for 200% of line current rating to handle zero sequence harmonics flowing through the neutral.
  • NEMA 1 & 3R indoor (refer to catalogue for details) powder-coat drip-proof enclosure is standard. Weather shield kit is available for conversion to NEMA 3R outdoor.
  • NEMA 3R, 4 & 4X enclosures are available. Stainless Steel or aluminum enclosures are optional.
  • CSA Certified / UL listed
  • Qualified to the seismic requirements
  • Copper (Cu) or Aluminum (Al) windings
  • Copper C&C grounding strap
  • Robust packaging with top and side protection protects against shipping damage
  • Accessible mounting flanges with front/back slotted mounting holes make installation easier
  • 100% Factory tested
  • Clear, Comprehensive Documentation and labeling

Product Specification

Capacity  3 to 333 kVA Single Phase and 5 to 900 kVA Three Phase
Voltage Class  600V
Cooling  Self Cooled (ANN / AN)
Frequency  60Hz (50/60Hz Optional)
Conductors  Copper (Cu) or Aluminum (Al) Windings
Insulation System  220°C (150°C rise) (optional 115°C & 80°C rise available)
Impregnation  Polyseter Resin Dipped and Baked

 Meets North American Energy Efficiency Standards:

  • Canada - (NRCan 2019) SOR/2018-201, Amd. 14 & ON Reg. 404/12
K-Factor  Suitable for non-sinusoidal current load with a K-factor not to exceed 4
Primary Taps  Typically +/-2 x 2.5% taps (refer to dry type distribution transformer catalogue)
Sound Level  Meets NEMA ST-20
Enclosure Type  Type 1 or 3R Indoor (refer to catalogue)
Enclosure Finish  ANSI/ASA 61 Grey
Warranty  12 Months (See Warranty and Limitations)
Quality System  ISO 9001:2015 Quality Management System
  • CSA Certified
  • UL Listed
Reference Standards
  • CSA C22.2 No 47
  • CSA C9
  • IEEE C57.12.01
  • IEEE C57.12.91
  • IEEE C57.110
  • NEMA ST-20
Optional Features & Accessories
  • Thermal Sensing & Indication
  • Thermometers (Analog/Digital)
  • Thermostat Alarm / Trip (N.O. /N.C. Contacts)
  • Electrostatic Shielding
  • Rated to Handle Current Harmonics (K4, K9, K13, K20)
  • Anti-Condensation Strip Heaters
  • Surge Protection Devices
  • Anti-Vibration Pads
  • Type 1, 2, 3R, 4, 4X or 12 Enclosure
  • 304 or 316L Stainless Steel Enclosure
  • Custom Enclosure Finish (Color)