For example: Agilent E4440A or Anritsu 68369
Transistor Devices Electronic Loads
Transistor Devices DLF400-600-4000
Electronic Load 1.2-400v 0-600a 4kw

Manufacturer: Transistor Devices
Transistor Devices DLP130-50-2500A
Electronic Loads 130V, 50A, 2500W

Manufacturer: Transistor Devices