The Greenlee 5990A is a 5 kV insulation tester and megohmmeter built for cable and rotary‑equipment testing. Features include automatic discharge after testing, auto‑calibration at start‑up, five preset DC test voltages (250 V, 500 V, 1 kV, 2.5 kV, 5 kV), a resistance range from 0.12 MΩ to 999 GΩ, an LCD display with bar‑graph, and a CAT IV, 600 V safety rating.