Head Mounted Temperature Transmitter

Head mounted temperature transmitter converts the temperature signal (usually a nonlinear millivolt or resistance signal) sent by the temperature sensor into its supposed temperature value and its output signal value (usually a standard signal of a current of 4~20mA/DC or a voltage of 1~5V/DC, which are in a linear relationship with actual temperature). The functional device is called a smart temperature transmitter.

Head mounted temperature transmitter, by input signal, is divided into the thermocouple and rtd temperature transmitter. By the application, it is divided into the integrated temperature transmitter with the temperature sensor structure and the frame bracket/cabinet-mounted temperature transmitter installed separately from the temperature sensor. The transmitter is divided into isolated type and non-isolated type by the processed method of input and output signal. The integrated temperature transmitter refers to the transmitter that is mounted into the terminal enclosure of the thermocouple or thermistor, allowing the thermocouple or thermistor to directly output a standard signal of 4~20mA/DC or 1~5V/DC from the measurement site. Generally, two-wire leads are used as both the power line and the signal lane.

Main Technical Parameter: Power supply should be outputting DC voltage of 24V±10%. Insulation resistance should be ≥50MΩ. Resistance should be ≥300Ω under working current of 4~20mA. Implemented standards are Temperature Transmitters for Use in Industrial-process Measure and Control Systems (GB/T 28473-2012) and Integrative temperature transducer (JB/T 12599-2016).

Transmitter with two-wire technology.

Installation in connection heads of temperature sensor.

Output signal
Supply voltage: 12…30VDC
Normal loop current: 4…20mA
Max. load: (Uaux-12V)/0.022Ω
Out-of-range current: Under lower range 3.84mA
Over upper range: 20.5mA
Sensor break or short-cut: 3.6mA or 22.8mA, configurable
Rated conditions
Operation temperature: -40…+80℃
Storage temperature: -40…+80℃
Relative humidity: ≤98%, condensing
Electromagnetic compatibility: According to GB/T 18268-2000
Construction
Material: Plastic
Weight: 25g
Cross section of the connecting cables Max. 2.5mm2
Degree of protection: IP40
The factory set
The input signal
The measuring range

Application Scenarios

With core advantages of "integration, easy installation and stable performance", this product is widely used in industrial production scenarios requiring temperature signal conversion, especially suitable for space-constrained or wiring-simplified working conditions, mainly including:

Industrial Automation Production Lines: Temperature signal conversion for machine tools, assembly lines, reactors and other equipment. Integrated installation does not occupy additional space, enabling seamless connection with PLC and DCS systems.

Chemical and Petroleum Industry: Temperature monitoring of pipelines, storage tanks and other equipment. The two-wire system simplifies on-site wiring, and it can still work stably in high-humidity and electromagnetic interference environments.

Power Industry: Temperature signal transmission for transformers, switchgear and other equipment. Isolated-type products resist strong electromagnetic interference to ensure signal accuracy.

Intelligent Manufacturing and Electronics Industry: Temperature monitoring of electronic component production equipment and precision instruments. Compact size adapts to narrow spaces inside equipment.

HVAC and Refrigeration Industry: Temperature control of central air conditioning and cold chain equipment. Wide operating temperature range adapts to diverse indoor and outdoor environments, and linear signals facilitate temperature control adjustment.

Metallurgy and Machinery Manufacturing Industry: Temperature monitoring of heat treatment furnaces, gearboxes and other equipment. Integrated design reduces on-site maintenance workload, and fault alarm function improves operation and maintenance efficiency.

Product Advantages

Low Installation and Maintenance Costs: Integrated inside the sensor junction box, no additional installation space or brackets required; two-wire wiring reduces wire and construction costs. Later maintenance only targets the integrated sensor-transmitter unit, achieving higher efficiency.

High Space Utilization: Weighing only 25g, the plastic housing is compact and lightweight, no additional load on the sensor, especially suitable for space-constrained installation scenarios.

Reliable Signal Transmission: High-precision linear conversion + strong EMC design effectively resists industrial interference. The fault current alarm function facilitates quick problem location and reduces downtime.

Wide and Flexible Adaptability: Supports two input signals (thermocouple and RTD), optional isolated/non-isolated types, and wide-voltage power supply (12~30VDC) to adapt to different industrial power supply conditions.

Standardized and Compliant Design: Fully complies with national industry standards, outputs standard industrial signals, and can be seamlessly connected with various industrial instruments and control systems without additional adaptation components.

Frequently Asked Questions

What are the core differences between head-mounted and rail-mounted temperature transmitters? How to choose?

Answer: The core differences lie in installation method and applicable scenarios: Head-mounted transmitters are integrated inside the sensor junction box, no control cabinet required, suitable for space-constrained or complex wiring sites; rail-mounted transmitters need to be installed on DIN35 rails, suitable for centralized control and unified management of multiple devices. When choosing, select head-mounted for sites without control cabinets or narrow spaces, and rail-mounted for centralized management and multi-transmitter linkage.

How to judge if the transmitter is in fault status?

Answer: Judge by output current: ① Current of 3.6mA or 22.8mA → Sensor open/short circuit (need to confirm the configured fault current type); ② Current of 3.84mA → Below measurement range; ③ Current of 20.5mA → Above measurement range; ④ No abnormal current mentioned above but distorted signal → Check if wiring, power supply or sensor is normal.

What precautions should be taken for two-wire wiring?

Answer: ① Strictly distinguish positive and negative poles to avoid equipment damage due to reverse connection; ② Control the wire cross-section within 0.5~2.5mm² to avoid signal attenuation caused by excessively thin wires; ③ Ensure the power supply voltage is within 12~30VDC, and the load resistance meets the requirement of (auxiliary voltage - 12V)/0.022Ω to avoid signal output impact due to excessive load.

Can the product be used outdoors or in high-humidity environments?Answer: Yes. The product has an operating temperature of -40~+80℃, resistant to ≤98% RH high humidity (condensation allowed), and IP40 protection level for dust prevention. However, it is necessary to ensure the sensor junction box is well-sealed to avoid direct rain immersion. For outdoor use, it is recommended to add an additional rain cover.

When the sensor type or range needs to be changed, does the transmitter need to be replaced synchronously?

Answer: No overall replacement is required. Configurable on-site models can directly reset the sensor type and range; fixed models need to contact the manufacturer for parameter recalibration without hardware replacement, only professional personnel need to adjust through configuration tools, featuring flexible adaptability.

What problems will insufficient insulation resistance cause? How to avoid it?

Answer: Insufficient insulation resistance will cause signal interference, transmission distortion, and even leakage risks. Avoidance methods: ① Ensure terminals are dry and clean without dust or moisture during installation; ② Keep away from strong electromagnetic interference sources and corrosive media; ③ Regularly check if wiring terminals are oxidized, and clean or replace them in a timely manner if problems are found.

Manual Welding

Automatic Welding

Insulation Testing

Laser Marking

Warehouse Managing

Thermocouple Assemble

Vacuum Leak Detection

Surface Polishing

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