1, input overload protection;
2, output over-current limit protection;
3, output current long-term short circuit protection;
4, two-wire port transient inductive and surge current TVS suppression protection;
5, the working power overvoltage limit protection ≤ 35V;
6, reverse working power protection.
1, is not susceptible to parasitic thermocouple and along the wire resistance drop and temperature drift, can be used very cheap finer twisted pair wire;
2. When the output resistance of the current source is large enough, the voltage in the wire loop is sensed by the magnetic field coupling and will not have a significant effect. Because the current caused by the interference source is extremely small, the interference can be reduced by using a twisted pair cable in general;
3, capacitive interference will cause the receiver resistance related error, for 4-20mA two-wire loop, the receiver resistance is usually 250Ω (sample Uout = 1 ~ 5V) This resistance is not small enough to produce significant errors, therefore, can The allowable length of wire is longer and longer than the voltage telemetry system;
4, each single reading device or recording device can be switched between different channels in the length of the wire, not because of the length of the wire caused by the difference in accuracy;
5. Use 4mA for zero level, which makes it easy to judge the open circuit or sensor damage (0mA status).
6, in the two-wire output port is easy to add anti-surge, lightning protection device, is conducive to safety lightning explosion.