Distinguish between true and false current and voltage transmitters
When the primary side is overloaded, the output current does not exceed 25.000mA+10%. Otherwise, the 24V working power supply and A/D input clamp circuit for the transmitter in the PLC/DCS are damaged due to excessive power consumption. The internal output of the shot is also damaged due to excessive power consumption. If there is no A/D input clamp circuit, the output current will not exceed 25.000mA+10% when the primary side is overloaded, otherwise the PLC/DCS will be transmitted. The 24V working power supply and A/D input clamp circuit used by the device are damaged due to excessive power consumption. In addition, the output of the transmitter is also damaged due to excessive power consumption, and the A/D input clamp circuit is even more suffer. ;
When the working voltage is 24V, the transmitter must not be damaged and must have polarity protection;
When the induced surge voltage exceeds 24V, there is no clamp identification: in the two-wire output port and an AC 50V pointer type head, use AC 50V to connect two lines to instantly touch the two-wire output port to see if there is any clamp. How many volts can be clamped at a glance;
Discrimination with or without polarity protection: use the pointer multimeter Ω multiplied by 10K file to measure the two-wire output port positively and positively. There is always an Ω resistance value infinitely large, and there is polarity protection;
There is a non-polar output current for a long time short-circuit protection: when the primary input is 100% or the overload is greater than 125%-200%, the load is short-circuited by 250Ω, and the short-circuit protection limit is measured at 25mA+10%;
Industrial grade and civil commercial grade identification: industrial grade operating temperature range is -25 degrees to +70 degrees, temperature drift coefficient is 100ppm per degree change, that is, temperature changes by 1 degree per degree, accuracy changes to one ten thousandth; civil commercial The working temperature range is 0 degrees (or -10 degrees) to +70 degrees (or +50 degrees). The temperature drift coefficient is 250ppm per degree, that is, the temperature changes by 1 degree per degree, and the accuracy changes to 2.5 parts per million. The temperature drift coefficient of the current and voltage transmitter can be tested and verified by the incubator or the high and low temperature box.
When the two lines are clamped due to inductive lightning and induced surge voltage exceeding 24V, the transmitter should not be damaged; generally 1-2 TVS transient protection diodes 1.5KE are connected in parallel between the two lines to suppress the interval of every 20 seconds. The impact of a positive and negative pulse of a pulse width of 20 milliseconds at a time, the transient withstand impact power of 1.5KW-3KW;
The reference should be stable, 4mA is the corresponding input zero reference, the reference is unstable, and the precision linearity is determined. The zero drift of 4mA within 4 minutes of cold boot does not exceed 4.000mA0.5%; (ie 3.98-4.02mA) ), the voltage drop on the load of 250Ω is 0.995-1.005V, the foreign IC core piece uses an expensive energy gap reference, and the temperature drift coefficient changes by 10ppm per degree;
The internal circuit consumes a total of current. When the working voltage is 24.000V, the full-scale 20.000mA reading will not change due to the load 0-700Ω change; the change does not exceed 20.000mA0.5%;
When the full-scale 20.000 mA, when the load is 250Ω, the full-scale 20.000mA reading will not change due to the operating voltage of 15.000V-30.000V; the change does not exceed 20.000mA0.5%;
When the primary input overload is overloaded, the current must be limited: when the primary input overload is greater than 125%, the output overcurrent limit is 25mA+10% (25.00-27.50mA). The voltage drop on the 250Ω load is 6.250-6.875V.
Detailed technical parameters reference: http://
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PRESS:6.0MPa(max)
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Compression ratio/% 7~17
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