9. Electrical Isolation

The Joulescope is electrically isolated between the USB interface and the IN/OUT sensor. Joulescope is rated to ±48V between USB ground and any of IN+, IN-, OUT+, and OUT-. The individual component ratings far exceed this specification. The components are:

Part #	Mfgr	Description	Isolation working	Isolation 60s	Isolation 1 s
760390014	Wurth	Transformer	400 VRMS	2500 VAC	3125 VAC
Si8661BB-B-IS1	Silicon Labs	Digital isolator	445 VRMS		4500 VRMS
TLP2361(TPL,E	Toshiba	Opto isolator	500 VRMS	3750 VRMS

The printed circuit board (PCB) clearance between the isolated sensor side and the USB host side is 1 mm. The use of an aluminum enclosure effectively limits the isolation voltage and requires that USB chassis ground surrounds the sensor edges. If you use Joulescope in a custom application without the standard enclosure, the four chassis ground rails (2 top & 2 bottom) can be cut around the isolation line to give a 4 mm PCB clearance between the USB host side and the sensor side.