there are (3) electronic pieces , be sides the various wires
the 'Hall effect sensor' (not a transformer), yes it connects to the data sending unit
the 'data module/wireless sender which can power the display'
the display unit which can be used wireless and powered separately from the data sender
this one can be powered by 6-60vdc
can measure 0-120vdc, and 100amp
think of the display as a combination remote display and keyboard
think of the sender as the data accumulation module and remote connection to the display
the hall effect device is the current flow sensor
voltage measurement is taken by the data unit from its power input line
there are units that measure 200, 300, 500 amps
i will follow after it is installed