passive isolator with a channel safe isolation for electrical isolation of current signals without auxiliary energy, input: 0 - 20/4 - 20 mA, output: 0 - 20/4 - 20mA, does not require auxiliary power, and test input voltage output: 4KV (50Hz 1 min.). Type: MCR-SL-1CLP-II-00-4KV. Phoenix Contact.