A Study of Breakdown Properties of HFO Gas under DC and Impulse Voltage

The dielectric properties of the hydro-fluoro-olefin gas HFO1234ze(E) are studied by the measurement of breakdown voltage versus pressure in two typical conditions: with uniform electric field under high voltage DC ramp, and with non-uniform electric field under impulse voltage. Solid by-products are generated during breakdown experiments, taking the form of black dust. These by-products do not produce an appreciable decrease of breakdown voltage of the gas. In uniform field, HFO shows a breakdown voltage about 83% that of SF6 in identical conditions. In divergent field, increasing the pressure induces a moderate increase of the impulse breakdown voltage. HFO shows favorable properties in the view to replacing SF6 for the insulation of medium voltage systems.