Description
The TRMA is a room temperature sensor, manufacturer type Müller MITS.
It is built for air-conditioning and cold storage – refrigeration plants on ships, cold rooms, building services. The housing is screwed to the wall, the short protective tube reaches into the room. Two versions are available: the sensing element sits either directly on the connector – the sensor then outputs its resistance – or behind a HART transmitter that turns it into 4 … 20 mA.
The input takes one or two Pt100 or Pt1000 in 2-, 3- or 4-wire connection, in classes A, B and AA. With an amplifier, one Pt100 is provided for. The measuring range runs without an amplifier from -30 to +90 °C, with an amplifier from -30 to +80 °C at a smallest span of 50 K – the same difference applies to the working temperature of the device.
The current output delivers 4 … 20 mA with HART in the 2-wire loop, overall range 3.6 … 21 mA, with 21 mA on break, short circuit or underrange. Total error is 0.3 % of the range at 16 bit resolution, the measuring rate 10 measurements per second, the filter 0 … 99 s. Setting is done in software over HART: LRL, URL, LRV, URV, filter, adjustment and simulation. Supply comes from the HART current loop with 12 … 40 VDC, load R = (UB − 12 V) / 21 mA, with reverse polarity protection.
Mechanically: PBT GF30 housing in black, flammability UL94 HB, dimensions approx. 117 × 28 × 32 mm, fastening through two Ø 4.6 mm holes 45.5 mm apart, weight 50 g, any mounting position. The protective tube is fixed at 30 mm and Ø 6 mm – other lengths are not documented. Protection is at least IP 65 but depends on the chosen connection; the manufacturer gives no assignment. Ten connections are available, from M12×1 to a cable outlet – two sensors do not fit every connector.
Configuration uses the HART interface with USB and software; when communicating through a HART modem a minimum resistance of 250 Ω has to be taken into account. No CE marking is documented in the manufacturer's data sheet and no declaration of conformity is available. UL94 HB is the lowest grade in the series.
Advantages at a glance
- Room sensor for cold rooms, air-conditioning and building services
- Pt100 or Pt1000, classes A, B and AA
- Two versions: resistance direct or 4 … 20 mA with HART
- Range -30 to +90 °C without, -30 to +80 °C with amplifier
- Total error 0.3 % of the range, 16 bit
- PBT GF30 housing, only 50 g, wall fixing 45.5 mm
- Protective tube 30 mm, Ø 6 mm
- Protection at least IP 65
- Setting in software over HART