When evaluating a China-based single pole transformer manufacturer, begin with the electrical duty, not the advertised price. Confirm rated capacity in kVA, primary and secondary voltages, frequency, phase, and connection method. These details must match the installation.
Check impedance, no-load loss, load loss, temperature rise, and insulation level. For outdoor units, review the enclosure, oil sealing, corrosion protection, and bushing design. Small differences matter. A transformer with lower losses may reduce operating costs over many years. However, unusually low figures deserve verification rather than immediate trust.
Ask for routine test records, type-test evidence, material traceability, and a clear inspection plan. Confirm whether tests follow applicable IEC or national standards. Factory quality should include winding checks, insulation tests, leak testing, and dimensional inspection. Also examine delivery protection, spare parts, warranty terms, and technical support. Good documentation is practical evidence of control. Price alone is weak evidence.
One common mistake is accepting a standard design without checking site conditions. Ambient temperature, altitude, lightning exposure, and load variation can change the required specification. I would request drawings and a nameplate sample before approval. No perfect specification exists. Recheck the assumptions. A qualified manufacturer should explain limitations, not hide them.