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ReliaGear XFMR Guard I Noise Isolation

Guard I Noise Isolation - ABB LV Transformer

Guard I™ Noise Isolation Transformers provide common mode noise signal between neutral and ground and transverse mode noise protection. Common mode noise is caused by electromagnetic interference, radio interference and ground loops.


  • Extra protection for sensitive equipment
  • Designed to help reduce operating costs
  • Easy access for installation and service


  • Full width copper electrostatic shielding standard                                   
  • Electrostatic shield ground wires are terminated to a common ground lug
  • Unique core and coil design using grain-oriented silicon steel
  • Core and coil assemblies mounted on rubber isolation pads
  • Single piece front/back
  • Outward facing feet 
  • Lifting eyes provided in top clamp
  • Lug kit included with most units up through 150kVA
  • Copper ground bar kit included with most units up through 150kVA
  • Copper ground strap 

Technical specifications

  • 15 – 500 kVA
  • 120 db common mode noise protection
  • 30 db transverse mode noise protection
  • Three-phase
  • Copper or aluminum windings
  • NEMA 1 and/or 2 drip-proof enclosure
  • Weather shield available for field conversion to NEMA 3R
  • NEMA 3R stainless steel (Type 316) available through 150 kVA

Certifications and standards

  • DOE Standards
  • Seismic qualified


  • Office buildings
  • Lighting circuits
  • Data centers
  • Medical facilities