application
Usually used in conjunction with display instruments, recording instruments, electronic computers, etc., with an output of 4-20mA. Directly measure the temperature of liquid, vapor, gas media, and solid surfaces within the range of 0-1800 ℃ in various production processes.
characteristic
● Two line output of 4-20mA, strong anti-interference ability;
Save the cost of compensating wires and installing temperature transmitters;
● Large measurement range;
Cold end temperature automatic compensation, non-linear correction circuit.
Working principle
The change in thermoelectric potential (resistance) measured by a thermocouple (resistor) in working condition generates an unbalanced signal through the bridge of a temperature transmitter, which is amplified and converted into a 4-20mA DC electrical signal for the working instrument to display the corresponding temperature value.
Main technical parameters
○ Product execution standards
IEC584
IEC1515
IEC751
JB/T7391-94
Output signal: 4-20mA, load resistance 250 Ω, transmission wire resistance 100 Ω
○ Output method: Two line system
○ Tolerance level: 0.1; 0.2； zero point five
○ Power supply: 24V DC±10%
○ Protection level: IP65
insulation resistance
The insulation resistance between the instrument output terminal and the casing should not be less than 50 Ω
thermal response time
When there is a step change in temperature, the time required for the current output signal of the instrument to change to 50% of the step change is usually represented by τ 0.5. When the step response stabilization time of the temperature transmitter does not exceed one-fifth of the thermocouple (resistance) thermal response stabilization time τ 0.5, the thermocouple (resistance) thermal response time is used as the thermal response time of the instrument; When the step response stability time of the temperature transmitter does not exceed half of the thermal response stability time τ 0.5 of the thermocouple (resistance), the thermal response time of the temperature transmitter is used as the thermal response time of the instrument.
Basic error
The basic error of the instrument should not exceed the combined error of the basic errors of the thermocouple (resistor) and temperature transmitter.
