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application
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Integrated digital display temperature transmitterUsually 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.
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characteristic
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● 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.
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Working principle
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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.
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Integrated digital temperature transmitterMain technical parameters
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○ Product execution standards
IEC584
IEC1515
IEC751
JB/T7391-94
○ Temperature measurement range and allowable deviation
● Thermistor
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model
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Graduation
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Temperature measurement range ℃
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accuracy class
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Allowable deviation
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WZPB
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Pt100
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-200～+500
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A-level
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±(0.15+0.002|t|)
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Grade B
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±(0.30+0.005|t|)
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WZCB
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Cu50
Cu100
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-50～+100
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-
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±(0.30+0.006|t|)
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● Thermocouple
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Graduation |
Allowable error and material grade |
| Level I |
class ii |
| Allowable deviation |
Temperature measurement range ℃ |
Allowable deviation |
Temperature measurement range ℃ |
| WRNB |
K |
±1.5℃
±0.004│t│ |
-40～+375
375~1000 |
±2.5℃
±0.0075│t│ |
-40～+333
333~1200 |
| WRMB |
N |
±1.5℃
±0.004│t│ |
-40～+375
375~1000 |
±2.5℃
±0.0075│t│ |
-40～+333
333~1200 |
| WREB |
E |
±1.5℃
±0.004│t│ |
-40～+375
375~800 |
±1.5℃
±0.004│t│ |
-40～+333
333~900 |
| WRFB |
J |
±1.5℃
±0.004│t│ |
-40～+375
375~750 |
±1.5℃
±0.004│t│ |
-40～+333
333~750 |
| WRCB |
T |
±1.5℃
±0.004│t│ |
-40-～+125
125~350 |
±1℃
±0.0075│t│ |
-40～+333
133~350 |
| WRPB |
S |
±1℃
±[1+0.003（t-1100）] |
0～+1100
1100~1600 |
±2.5℃
±0.0025│t│ |
0~600
600~1600 |
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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
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insulation resistance
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The insulation resistance between the instrument output terminal and the casing should not be less than 50 Ω
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thermal response time
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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;
equaltemperature transmitterWhen the step response stability time of the thermocouple (resistance) does not exceed half of the thermal response stability time τ 0.5, the thermal response time of the temperature transmitter is used as the thermal response time of the instrument.
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Basic error
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The basic error of the instrument should not exceed the combined error of the basic errors of the thermocouple (resistor) and temperature transmitter.
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Integrated digital temperature transmitterwork environment
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Installation site level
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Temperature ℃
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Relative humidity%
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Atmospheric pressure KPa
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Cx1
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-25～+55
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5~95
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86~106
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Cx2
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-25～+70
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Cx3
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-40～+80
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Determination of support tube length
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The working temperature of the temperature transmitter is the sum of the shell temperature rise caused by the support tube and the ambient temperature. The temperature rise of the shell caused by the support tube is shown in the following figure:
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Instrument wiring method
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Junction box method
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Model naming method
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W
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Temperature instrument
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category
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R
Z
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thermocouple
thermal resistance
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Index number of temperature sensing element material |
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M
N
E
F
C
P
Q
R
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Nickel chromium silicon nickel silicon N
Nickel chromium nickel silicon K
Nickel chromium copper nickel E
Iron Copper Nickel J
Copper Copper Nickel T
Pt-Rh10-Platinum S
Pt-Rh13-Platinum R
Pt-Rh30-Platinum6B
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P
C
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Platinum Pt100
Copper Cu50
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B
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temperature transmitter
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Installation fixed form
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1
2
3
4
5
6
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No fixed device
Fixed thread
Movable flange
Flange
Flexible tube connector type
Fixed thread cone form
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Form of junction box
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2
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Anti spray type
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Protection tube diameter
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0
1
2
3
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Φ16
Φ12
Φ 16 high alumina pipe
Φ 20 high alumina pipe
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Workplace format
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G
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variable cross-section
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Display mode
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N
S
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Display without header
Digital display (LCD liquid crystal display)
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W
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R
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N
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B
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--
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2
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2
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0
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G
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N
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Typical Model Example
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Selection Notice
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1) Model number
2) Dividing number
3) Temperature range
4) Accuracy level of thermocouple (resistor)
5) Installation fixed form
6) Material of protective tube
7) Length or insertion depth
Example A: Withtemperature transmitterThermocouple, K-thermocouple, 0-400 ℃, accuracy level 0.5%, fixed thread M27 × 2, protective tube 316L, length 450mm, insertion depth 300mm. Model PN-WRNB-220, 0-400 ℃, L=450 × 300, protective tube 316L, thread M27 × 2, accuracy level 0.5%.
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