Resistance temperature transmitters operate on the measuring principle of Ohm’s Law, which states that a current between two points in a resistor is proportional to the voltage between the same points. This proportionality, or resistance, is routinely used to mathematically acquire an electronic value for the temperature of a measured system.
Both head-mount and field-mount temperature transmitters operate on the principle of electrical resistance. They use two-wire circuits to measure changes in voltage across the resistor and convert those changes into a thermal voltage signal. This signal can be displayed directly on a graphical indicator or transmitted for remote monitoring and data acquisition.
Despite utilizing near-identical measuring technologies, head-mount and field-mount transmitters are unique from one another. This blog post will explore the differences between the two component types in more detail.
Head-mount temperature transmitters are integrated directly into a temperature sensor’s connection head, enabling the component to be connected directly to a thermocouple or thermowell without a compensation cable or additional housing materials. This significantly reduces the wiring requirements of the component and minimizes the footprint of temperature-monitoring equipment.
ABB offers head-mount temperature transmitters in two distinct series; TTH200 and TTH300. These device lines are equipped with a universal sensor input with configurable output signals depending on your application requirements. Load independent 4 – 20 mA direct current (DC), and HART signals are available across both product lines. TTH300 head-mount temperature transmitters are also suitable for PROFIBUS and FOUNDATION Fieldbus.
Each of these head-mount temperature transmitters is suitable for use in hazardous applications, with demonstrable applications in temperature measurement of steam pipes in chemical facilities.
Field-mount temperature transmitters are measuring components that are independent from a temperature sensor. The two-wire resistor is mounted in its own robust housing with an indicator that can display accurate thermal voltages rapidly and in the field. These can be tube- or wall-mounted close to the temperature sensor to reduce the transmitter’s wiring requirements.
Our field-mount temperature transmitters are also available across the TTH200 and TTH300 range, with the same output configurations available. An additional WirelessHART transmitter is available, enabling in situ temperature monitoring with total elimination of wiring infrastructures altogether.
Choosing between a head-mount and a field-mount temperature transmitter largely depends upon application requirements. Both are typically integrated into die-cast aluminium or stainless-steel housings, with internally-protected electronics to ensure maximum protection from invasive and corrosive media. Explore our extensive range of temperature transmitters to discover the component most suitable for your facility.
ABB is a world-leading manufacturer of measurement instrumentation for process control and monitoring in some of the most demanding industrial operating conditions worldwide. We supply the broadest range measuring components, including a robust selection of temperature transmitters for commercial, industrial, and laboratory applications.
Find out more with our primer on What is a temperature transmitter? Or, if you would like to contact us about a specific product line of temperature transmitters, get in touch using the form below.