AMR-OP40C – measuring CO2, temperature and humidity in a single device

AMR-OP40C – measuring 3 quantities in a single device

In the article on influence of CO₂ concentration on humans and on quality of interior environment in buildings, we briefly mentioned devices evaluating air quality indicators. One of them is the combined on-wall controller AMR-OP40C for measurement of CO₂, temperature and humidity.

AMR-OP40C is suitable for use in both office spaces and public spaces such as schools, stores, hospitals, etc. It does not feature any controls and requires no user handling. The controller comes in a basic design ABB Time in various colours; we can therefore integrate it into multi-frames of devices of the same design. The device is mounted on a standard junction box KU68.

The controller AMR-OP40C is used as a periphery for control and monitoring systems. It is connected to a superior system by means of serial interface RS485 with protocol MODBUS RTU, or with AMiT-made ARION protocol. It is powered from a 24 V DC source.

The controller is made with defined basic functions, and the communication interface allows us to edit certain parameters during operation. The basic function is continuous measurement of CO₂ in the room and visualization of measured levels using an embedded three-colour LED located on the front panel. Green LED colour informs us on low (satisfactory) CO₂ concentration, orange represents increased concentration and red announces that the limit set has been exceeded. Values of individual levels are set using the communication interface; e.g. the green colour usually marks concentration up to 900 ppm, yellow up to 1,500 ppm, and red marks higher values. Furthermore, there is the option to set a brief acoustic signal to sound when LED turns red which repeats three times within two minutes. At the same time, the controller provides the superior system with current data on temperature and relative air humidity.

Controllers of the series AMREG (AMR-OP) are typically freely programmable, i.e. the application technician may completely re-program the controller functionality using DetStudio development environment and add other parameters. For example, the technician may re-program the LED brightness (to be dimmed at night or turned off entirely), change the acoustic signal in terms of its length, intensity, frequency, etc.

Measurement of CO₂ is provided by a reliable and long-term stable sensor type NDIR with automatic calibration. All the device needs to work correctly in this mode is “proper” ventilation of the measured room at least once a week. Spaces with limited possibilities of proper ventilation may use manual/controlled calibration.

Wireless measurement of CO₂

Apart from the “wire” controller AMR-OP40C with communication interface RS485, there is a wireless-communication variant P8_T_CO2_TE with practically identical functional use in identical design. The unit requires power supply 230 V AC and uses the reliable wireless communication system Poseidon 868 MHz for data transmission. Installing such measuring device is extremely easy. All we have to do is find a spare socket and install this device in its place. Or we can add another junction box KU68 with 230 V AC inlet next to a switch or a socket. In this case, we use an AMR-CP24 data concentrator to collect data on superior measurement and regulation systems; the concentrator uses communication interface RS485 (MODBUS RTU, DB-Net) or Ethernet (MODBUS TCP/IP, DB-Net/IP). The unit may also work entirely independently, without communicating with a superior system. It is able to use an embedded relay to turn on ventilation or any other device when the set limit CO₂ concentration is exceeded.

User-comfortable controllers for CO₂ measurement with a graphic display

The AMiT portfolio includes also other devices for CO₂ measurement. They are more user-comfortable on-wall controllers with graphic touch screens of the series AMR-OP70C. These devices display current measured values on the screen and the user is able to set regulation modes or directly control lights, shades and other equipment of the room simply by touching the screen controls. These design controllers are suitable for office spaces, laboratories, hospitals or homes.

On-wall controllers AMR-OP40C and the wireless variant P8_T_CO2_TE have been successfully used in pilot installations in elementary schools within the project Zdravá škola (Healthy School) under the auspices of the Czech Green Building Council. Sensors are available also on “measurement cases” used for temporary measurement of CO₂ concentration, temperature and humidity in rooms and transmit data on-line into the cloud system LookDet. We offer the measurement cases to our business partners to measure air quality in the room.