Description
The TRMC is a room climate sensor for temperature and relative humidity, manufacturer type Müller RKS.
It is wall-mounted, combines two measured variables in an aluminum housing and displays them on site – designed for refrigeration systems on ships, for cold rooms and for building services. The housing is an aluCase AC092 with 160 × 90 × 60 mm made of die-cast aluminum, weighing a maximum of 1.1 kg; connection is via screw terminals up to 2.5 mm² and three cable glands M16x1.5. The protection class is IP 65 without and IP 63 with humidity sensor, which sits behind a PTFE filter.
Where otherwise two devices would be wall-mounted, here there is one: transmitter and display are not accessories, but part of the order key. The display is 4-digit and 7-segment, 8 mm high, its range of -999 … 9999 digits is programmable.
Temperature is measured by 1× or 2× Pt100 in 2-, 3- or 4-wire circuits in classes B, A, B 1/2 DIN and B 1/3 DIN, the protective tube is made of stainless steel 1.4571; the humidity sensor measures 0 … 100 % RH with ±2 % RH from 5 … 95 % RH at 10 … 40 °C. The two measured variables take separate paths: Humidity is output directly as 4 … 20 mA, 0 … 10 V or 2 … 10 V, for temperature a transmitter TAP2L or TMRO can be selected. The device is powered by 24 … 30 VDC; limit contacts are not mentioned in the data sheet.
Please note before ordering: With the humidity sensor, the protection class decreases from IP 65 to IP 63 – the PTFE filter must allow air to pass through, so the version with humidity is no longer protected against jet water. The humidity sensor requires air movement: at least 1 m/s across the sensor at the current output and 0.5 m/s at the voltage output; measurement in still air is not guaranteed. The source contradicts itself regarding the measuring range: feature list -40 … +80 °C, data table of the temperature sensor -50 … +100 °C – the smaller value is the safe one; the display only operates from 0 to +80 °C. The power supply is also stated differently twice in the sheet: feature list 24 VDC, order key 24 … 30 VDC – we use the value of the key. The protective tube is designated 1.4571, but not dimensioned; length and diameter must be requested. Long-term drift and calibration interval of the humidity sensor are not documented, nor are a CE mark and explosion protection.
Advantages at a glance
- Temperature and relative humidity in one device
- Humidity 0 … 100 % RH, ±2 % RH from 5 to 95 % RH
- 1× or 2× Pt100, classes B to B 1/3 DIN, measuring range -40 to +80 °C
- Separate outputs, humidity as 4 … 20 mA, 0 … 10 V or 2 … 10 V
- Display 7-segment, 4-digit, 8 mm, -999 to 9999 digits
- Aluminum housing 160 × 90 × 60 mm, maximum 1.1 kg, IP 65 – with humidity sensor IP 63