High potential (high voltage) Test and it is also known as Dielectric Withstand Test.
Hipot

70LBS
The PTS-75 is a CE marked DC hipot and megohmmeter in one convenient package for testing the dielectric strength and insulation resistance of electric insulation such as cable, switchgear, motors, transformer, insulators, generators, and other electrical apparatus.

Key Features:

Continuously adjustable output voltage
Fixed overload, factory set to 120% of rated output current
Zero start and external interlock provision
Dual-range voltmeter
Five-range current meter 0-1.0 mA DC with x1, x10, x100, x1k, and x10k multipliers
Five-range megohmmeter 100-1 MΩ with x0.1, x1, x10, x100, and x1k multipliers
Ferro-resonant line regulator for output voltage stabilization
Guard/ground return circuit
Automatic transit protected meters
Rugged case with cushion grips
Transit protected meters