Microgrids

Inverter duty. Specify inverter-duty transformers based on waveform, harmonics, filtering, impedance, and switching transients. Additional shielding or insulation can address identified stresses; otherwise, a standard transformer remains economical.

Step-up applications. Step-up operation affects winding energization, taps, grounding, and protection. For solar installations, verify connection, tap arrangement, and voltage rise at maximum export rather than assuming a standard step-down transformer is suitable in reverse.

Connection and grounding. Utility requirements and ground-fault studies define transformer connection, grounding, impedance, and neutral-grounding criteria. Each transformer should be designed to meet these project-specific interconnection requirements.

Outdoor construction. Type 3R suits many outdoor installations, while Type 4X or corrosion-resistant construction may be warranted for salt, spray, or severe contamination. Specify ambient, solar exposure, ventilation, and access based on actual site conditions.

Medium-voltage dry-type options. Rex VPI/VPE and cast-coil designs can serve collector and interconnection applications, including suitable 35 kV-class projects. Confirm kVA, BIL, cooling, enclosure, and certification for each application; some large outdoor installations may favor liquid-filled designs.

Sizing and configuration. Set kVA, impedance, winding connection, BIL and tap range from the inverter datasheet, collector-system study and utility agreement. For Canadian 600 V projects, coordinate the selected construction with CSA C22.2 No. 47, the Canadian Electrical Code as adopted locally and the provincial authority having jurisdiction (AHJ).

Footprint and installation. Review pad, skid or inverter-skid mounting, cable entries, terminations and cooling clearance against the site layout. Specify the outdoor enclosure and ambient rating for the installed configuration.

Monitoring and protection. Add winding-temperature sensing, surge protection, alarm contacts and SCADA outputs where the site’s remote operations plan requires them.