Product Wiring Installation Typical system connections for a 4-20 mA transmitter are illustrated on Figure 1. When using a load resistor care must be taken to ensure that the power supply voltage (VS) minus the voltage dropped (VD) across the load resistor (RL) is greater than the minimum operating voltage of the transmitter. This can be calculated as follows: VD = 20mA x RL VO < VS – VD When using a 250-Ohm RL, VS would need to be 5 volts greater than VO. Figure 1 Figure 2 Figure 3