iTemp TMT128

Summary

Product identification

• Product Name: iTEMP® TC TMT128
• Description: DIN rail mounted Temperature Transmitter for Thermocouples (TC)
• Type: TMT128

Application

• Temperature transmitter with fixed measuring ranges for converting TC input signals into a scalable 4 to 20 mA output signal.
• Input: Thermocouples (TC)
• Output: Analog, scalable 4 to 20 mA output signal

Features and Benefits

• High accuracy: 0.08 % of span
• Breakdown information in event of sensor break
• Galvanic isolation: 2 kV (from sensor input to output)
• Long-term stability: < 0.05 %/year
• Electromagnetic compatibility to IEC 61326
• Hazardous area approvals: ATEX, CSA, FM (EEx ia, nA, IS, NI, GP)
• GL Germanische Lloyd / marine approval
• UL recognized component to UL 3111-1

Function and System Design

• Measuring Principle: Electronic acquisition and conversion of input signals.
• Measuring System: Two-wire transmitter with analog output and measuring input for thermocouples.
• Measured Variable: Temperature
• Input Type: Thermocouples (TC)

Input Thermocouple Types and Measuring Ranges

Output Signal

• Analog Output: 4 to 20 mA
• Breakdown Information: To NAMUR NE 43
• Under-ranging: 3.8 mA (Standard)
• Over-ranging: 20.5 mA (Standard)
• Sensor Break: ≥ 21.0 mA (Standard), > 21.5 mA guaranteed if output setting is ≥ 21.0 mA.

Source Impedance

• Max. (V_{power supply} - 12V) / 0.022 A

Transmission Behavior

• Temperature linear

Cold Junction Compensation

• Internal cold junction (Pt100)
• Accuracy of cold junction: ±1 K
• Sensor current: ≤ 350 nA

Electrical

• Supply Voltage (Ub): 12 to 35 V, reverse polarity protection
• Permitted Residual Ripple (Uss): ≤ 3V at Ub ≥ 15V, f_max = 1 kHz
• Induced Current Requirement: ≤ 3.5 mA
• Current Limitation: ≤ 23 mA
• Switch-on Delay: 4 s (during switch-on procedure Ia ≤ 3.8 mA)
• Response Time: 1 s

Accuracy

• Reference Operating Conditions: Calibration temperature: +25 °C (77 °F) ± 5 K

• Maximum Measured Error:

  • Influence of supply voltage: ≤ ±0.01%/V deviation from 24 V
  • Influence of load: ±0.02%/100 Ω
  • Influence of ambient temperature (temperature drift) for Thermocouples (TC): Td = ±(50 ppm/K * max. measuring range + 50 ppm/K * of set measuring range) * Δϑ Δϑ = deviation of the ambient temperature from the reference operating condition (25 °C (77 °F) ± 5 K).

• Accuracy Table (Values refer to set span):

  Thermocouple Type (TC)	Accuracy (Typical)
  K, J, T, E, L, U	0.5 K or 0.08%
  N, C, D	1.0 K or 0.08%
  S, B, R	2.0 K or 0.08%

Long-Term Stability

• ≤ 0.1 K/year or ≤ 0.05%/year (Values under reference operating conditions; larger value applies)

Installation Conditions

• Installation Location: No restrictions

Environmental Conditions

• Ambient Temperature Limits: -40 to +85 °C (-40 to 185 °F) (for Ex-area, see Ex-certificate)
• Storage Temperature: -40 to +100 °C (-40 to 212 °F)
• Climate Class: As per IEC 60654-1, Class C
• Degree of Protection: IP 20
• Shock Resistance: 4g / 2 to 150 Hz as per IEC 60068-2-6
• Vibration Resistance: See 'Shock resistance'
• Electromagnetic Compatibility (EMC): Shock resistance and interference emission as per IEC 61326 and NAMUR NE 21.
• Condensation: Permitted

Mechanical / Hydraulic

• Weight: approx. 90 g (3.18 oz)
• Housing Material: PC/ABS, UL 94V0
• Terminals: Pluggable screw terminal, max. 2.5 mm² (16 AWG) solid, or strand with wire end sleeve.

Human Interface

• Display Elements: Illuminated yellow LED (2 mm, 0.08 in) signals device operation.
• Operating Elements: None on the device.

Certificates and Approvals

• CE-Mark: Device meets EC directives.
• Hazardous Area Approvals: ATEX, CSA, FM, TIIS, NEPSI (Specific details and Ex versions available in separate documentation).
• Ship Building Approval: GL (Germanischer Lloyd)
• Other Standards and Guidelines: IEC 60529 (IP-Code), IEC 61010-1 (Safety), IEC 61326-1 (EMC), NAMUR.
• UL: Recognized component to UL 3111-1.

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Disclaimer: This extraction may miss figures, footnotes, or revisions. Contractual data must match the OEM PDF revision used on the project.

Official datasheet (PDF)

Lenntech datasheet mirror