Instrumentation and control
Current loops
Voltage drop, load resistance and supply headroom.
Instrumentation and control
Current loop voltage drop
U = IR / 1000→Instrumentation and controlMaximum loop resistance
Rmax = (Vs − Vmin)/(I/1000)→Instrumentation and controlTransmitter terminal voltage
Vtx = Vs − IR/1000→Instrumentation and controlCurrent loop load power
P = (I/1000)²R→Instrumentation and controlCurrent from voltage and resistance
I = 1000U / R→Instrumentation and controlShunt selection from ranges
R = (Umax−Umin) / ((Imax−Imin)/1000)→Instrumentation and controlMaximum loop resistance with reserve
Rmax = (Us − Utx − Ures) / Imax→