When sourcing PCB mount voltage transformers, you must prioritize accuracy class (typically 0.1, 0.2, or 0.5) for precision measurement. Key electrical parameters include the rated primary/secondary voltage, transformation ratio, and rated burden (VA). Ensure the dielectric strength (isolation voltage) is at least 3kV to 4kV to protect sensitive downstream PCB components from high-voltage surges. Additionally, verify the frequency range (50Hz/60Hz) and phase shift specifications to ensure compatibility with your power monitoring or protection circuits.