Remote connections to current transmitters can sometimes be subjected to voltage surges. Best practice is to limit the maximum surge voltage applied to the XTR11x to as low as practical. Various Zener and surge clamping diodes are specially designed for this purpose. Select a clamp diode with as low a voltage rating as possible for best protection. For example, a 36-V protection diode provides proper transmitter operation at normal loop voltages, and also provides an appropriate level of protection against voltage surges. Characterization tests on several production lots showed no damage with loop supply voltages up to 65 V.

Most surge protection Zener diodes have a diode characteristic in the forward direction that conducts excessive current, possibly damaging receiving-side circuitry if the loop connections are reversed. If a surge protection diode is used, also use a series diode or diode bridge for protection against reversed connections.