Figure 1. 27RS Appearance and Dimensions.

New PC programmable model 27RS (RTD input, isolated) is a new addition to M-System’s Head-mount Temperature Transmitters. Newly developing 27R (RTD input, non-isolated) and 27TS (Thermocouple input, isolated) will be released in the near future. These models are designed with user-friendly versatile programming features, high accuracy, and to comply with ATEX and FM intrinsically safe approvals.

1. High accuracy
The 27RS RTD transmitter offers extremely high accuracy, ± 0.15°C (± 0.27°F), ± 0.075% of span or ± 0.075% of max. range = absolute range (greater of 0% and 100% range values), whichever is greater.

The 27RS maintains high accuracy in even severe environments, guaranteeing a temperature coefficient of 75 ppm/°C in the range of -40°C to 85°C (-40 to +185°F).

The 27RS features class-leading accuracy that stands out among the world’s head mount style transmitters.

Figure 2. 27RS schematic circuitry & connection diagram.

2. Easy configuration
Parameter settings are easily configured by dedicated PC configurator software model 27MCFG, such as input sensor type, number of wires, input temperature range, burnout, output limits (Upper / Lower), sensor calibration, output signal adjustment, and damping constant. Moreover, the ability of 300-point linearization and custom RTD tables gives this unit nearly universal capabilities as an RTD transmitter. The 27MCFG will be available to download at M-System web site (http://www.m-system.co.jp).

Figure 3. 27RS Function Monitor LED (Option).

3. Convenient function monitor LED
The 27RS is available with a convenient function monitor LED* (see Figure 3). This feature does more than simply enable you to confirm that the power is supplied, the flashing patterns help you easily identify the percentage of input signal and transmitter’s error status. The monitor assumes output based on 1 to 5V DC, converted as values 1 through 5.

A long flash corresponds to 1 (25% input), while a short flash corresponds to 0.2 (5% input), enabling to monitor in 5% increments (see Figure 4[a]).

Other flash patterns indicate status information such as burnout and input upper/lower limits (see Figure 4[b]).

Although the lamp is not visible when enclosed in the sensor head, we are confident that this design functions effectively during installation and when performing maintenance.

Figure 4. Function Monitor LED’s Input and Error Monitors.

4. EMC directive compliance
The CE Marking indicates that products comply with European Union directives concerning product safety and electromagnetic immunity. The 27RS complies with the EU’s Electromagnetic Compatibility (EMC) Directive.

Specifically, compliant products must offer outstanding stability in terms of radio noise and other forms of electromagnetic interference while limiting unnecessary emissions of electromagnetic radiation. Requirements that products also clear other tests including lightning surge and electrostatic resistance ensure that the CE Marking constitutes evidence of exceptional quality.

5. Intrinsically safe
Intrinsically safe is an essential requirement for transmitters that will be installed on-site or in remote locations. M-System anticipates receiving intrinsically safe certification for installation of the 27RS in Zone 0 environments under CE Marking ATEX directives and the FM standard.

The IEC60079-10 international standard classifies hazardous locations according to the possible presence of dangerous gases as follows:

• Zone 0 – a place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is present continuously or for long periods or frequently
• Zone 1 – a place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally
• Zone 2 – a place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only

* Availabilitiy is limited to models that are not compliant with intrinsically safe standards.