S40A is a type of 3‐phase protection relay test set, with 3×40A, 3×300V, and a local control system. The unit is user-friendly and is operated from a simple two-knob interface and does not require a laptop. You will receive next day UK delivery to your door when ordering from Sunbelt Rentals Test &. Home ponovo s40a protection relay test equipment 3i This model relay tester is designed with 3 currents (3*40A) and 3 voltages (3*150V). KINGSINE K3066 Protection Relay Tes.