Siemens 7NG3211 Temperaturtransmitter

Siemens 7NG3211 Head-Mounted Pt100 Temperature Transmitter

1. Grundlegende Produktpositionierung

7NG3211 corresponds to SITRANS TH100. It is a 2-wire 4–20 mA head-mounted transmitter dedicated exclusively to Pt100 without HART communication. It only supports resistance temperature detectors (RTDs) and is incompatible with thermocouples. Designed to fit DIN Type B connection heads (44 mm round), it serves as a general-purpose basic temperature transmission module for chemical, power and HVAC industries.

Full Order Code Breakdown (7NG3211-XNNXX)

Take common models `7NG3211-0AN00` and `7NG3211-1NN00` as examples:

1. 7NG3211: Fixed series prefix, representing standard round plastic housing of TH100
2. 1st suffix digit: Explosion-proof certification

0 = Intrinsically safe ATEX Ex ia/ib and NEPSI certification (for Zone 0/1 Gefahrenbereiche)

1 = Standard non-explosion-proof type (for ordinary safe areas)

3. 2nd character A/N: No electrical isolation (all TH100 variants feature no isolation)
4. Last three digits 00: Standard terminals, no optional extra functions
5. Kernelektrik & Measurement Specifications

2.1 Eingang (Pt100 IEC60751 only)

Wiring compatibility: 2-wire / 3-wire / 4-wire Pt100, configurable via software

Messbereich: -200 ~ +850°C

Minimum span: 25°C; Maximum span: 1050°C

Maximum total wire resistance: ≤20 Ω (suitable for long cables)

Measuring current: 0.4 mA, with immunity to 50/60 Hz power frequency interference

Genauigkeit (at 23°C ambient temperature): ≤0.1%FS; Temperature drift ≤0.1%FS per 10°C; Repeatability ＜0.1°C

Sensor fault signal (offener Stromkreis / Kurzschluss): Compliant with NAMUR NE43, configurable as either low fault level (3.6 mA) or high fault level (22.8 mA)

Filter damping: Einstellbar von 0 Zu 30 s via software, factory preset to 0 S

Verpolungsschutz, 12-bit resolution

2.3 Umweltfreundlich & Mechanische Parameter

Betriebstemperatur: -40°C ~ +85°C (transmitter body)

Abmessungen: Φ44 mm, Dicke 20.8 mm; Gewicht: 50 G

Max cross-section of cable for terminals: 2.5 mm²

Schutzstruktur: Potting plastic housing, compatible with standard temperature sensor connection heads

3. Terminaldefinition & Verdrahtung

Six terminals in total, divided into power circuit (Terminals 1, 2) and Pt100 sensor circuit (Terminals 3, 4, 5, 6)

1. Terminal 1 (+): Positive pole of 24 V DC-Stromversorgung
2. Terminal 2 (-): Negative pole of 4–20 mA signal (shared ground for 2-wire loop)

3/4/5/6: Terminals for Pt100 RTD wiring

3-wire Pt100: Terminals 3 Und 4 connect to two ends of RTD, Terminal 5 for compensation wire, Terminal 6 vacant

4-wire Pt100: Terminals 3&4 as one pair, Terminals 5&6 as another pair to eliminate lead resistance error

Critical note: Nach der Verkabelung, 2/3/4-wire Pt100 mode must be matched via SIPROM T software; otherwise severe temperature deviation will occur.

4. Konfiguration & Calibration Method
5. Mandatory tools: SIPROM T configuration software + dedicated USB modem
6. Configurable parameters:

Upper/lower measuring range limits, temperature unit (°C / °F)

Switch between 2-wire / 3-wire / 4-wire Pt100 modes

Filter damping time, sensor offset compensation (±100°C)

Fault output level (low limit: 3.6 mA / high limit: 22.8 mA)

3. Einschränkung: No HART protocol support. Calibration via handheld communicator is unavailable; offline configuration via computer USB only.
4. Explosion-Proof Certification List (0AN00 Explosion-Proof Model)

ATEX Ex ia IIC T4/T5/T6, FM and NEPSI intrinsic safety certifications. Applicable for flammable and explosive working conditions in Zone 0/1; Compliant with dust explosion protection Zone 21/22 Standards.

6. Kernunterschiede: TH100 (7NG3211) vs TH200 vs TH320

7. Typical Troubleshooting Matrix

8. Alternative Selection Solutions
9. Upgraded models with identical head-mounted installation form factor

Remote calibration with HART required: 7NG3212 TH200

Thermocouple compatible with electrical isolation: 7NG3213 TH320

2. Domestic substitutes for discontinued / out-of-stock units: 44 mm round head-mounted 2-wire 4–20 mA Pt100 transmitters with fully compatible mounting dimensions
3. DIN rail mounted alternative: Siemens SITRANS TR100 DIN rail temperature transmitter module
4. Industrial Application Scenarios

Energiewirtschaft: Temperature measurement for boilers, steam turbines and auxiliary equipment bearings

Chemisch & petrochemical industry: Explosion-proof temperature acquisition for pipelines and reactors

Pharmazeutisch & food industry: Temperature monitoring for sanitary tanks and heat exchangers

HVAC: Pt100 temperature detection for air ducts and chillers

Output Signal of Siemens 7NG3211 (SITRANS TH100)

1. Standard output type: 2-wire 4～20 mA analog current signal
2. No HART protocol support: Pure analog current output only, digital communication not available
3. Signal correspondence:

Minimum measuring temperature → 4 mA

Maximum measuring temperature → 20 mA

4. Two optional fault outputs (compliant with NAMUR NE43, software configurable):

Low fault level: 3.6 mA (sensor open circuit)

High fault level: 22.8 mA (sensor short circuit)

5. Over-range output: 3.84 mA when measured value below lower range limit; 20.5 mA when measured value above upper range limit
6. Power supply and signal share two wires; loop load driven by 24 V DC-Stromversorgung.

Full Accuracy Specifications of Siemens 7NG3211 (SITRANS TH100)

(Standard test condition at 23°C specified in original manufacturer manual)

1. Overall Basic Measuring Accuracy (Key Indicator)
2. Span ＜ 250°C: Maximum error ＜0.25°C
3. Span ＞ 250°C: Maximum error ＜0.1%FS (Voller Maßstab)
4. Nominal overall basic error for the unit: ＜0.1% of measuring span (at 23°C ambient temperature)

Calculation Examples for Intuitive Understanding

Range 0～100°C (span 100°C ＜ 250°C): Max error ±0.25°C

Range 0～500°C (span 500°C ＞ 250°C): 500 × 0.1% = ±0.5°C

2. Repeatability Accuracy

＜0.1°C, minimal fluctuation in repeated temperature measurements

3. Temperature Drift (Additional error induced by ambient temperature variation)

Max drift value: 0.1%FS per 10°C

Beispiel: 20°C ambient temperature fluctuation brings an extra 0.2% full-scale error

4. Other Additional Error Terms
5. Supply voltage influence: ＜0.01%FS per V
6. Load resistance influence: ＜0.025%FS per 100 Oh
7. Long-term drift: ＜0.025%FS per month
8. Measuring resolution: 14-bisschen
9. Ergänzende Bemerkungen
10. Stated accuracy only applies to the transmitter body, excluding inherent error of Pt100 sensor itself.
11. No built-in electrical isolation; extra measuring deviation will be introduced at sites with severe electromagnetic interference.
12. 2/3/4-wire Pt100 mode must be correctly configured via SIPROM T software; otherwise systematic deviation of several degrees Celsius will occur.

Translation Notes for Industrial Standard Terms