Temperature and Humidity Measurement System


A dedicated system is developed to monitor the:
  • Temperature of the BGV gas injection and window chambers
  • Temeprature and Dew point inside the detector tent, and inside the cooling manifold

The measurements are stored in the LHC Logging Database.

Initial functional requirements and progress updates can be found in this document.

Update May 2015: System overview after the addition of the humidity sensors.


Temperature sensor
  • 4-wire PT100 sensor from Radiospares, see specification sheet
  • Complies to norm IEC 751, which is used in the PLC to convert resistance to temperature

Humidity sensor

  • QuantaDat/nSens from Novasina, see webpage
  • Procurement with the help of Francisco Josa (EN-CV)
  • Consists of a electrolytic-resistive probe and a transmitter (for details, see the documents in the webpage above)
  • The sensor provides measurement of T and RH. The dew point is calculated by the transmitter.
  • The transmitter has 4 analogue outputs (can choose between T, RH, Dew point, ...; can choose the measurement range). In addition it has 2 relay switches which can be configured to provide an electric signal when a threshold is crossed (e.g. interlock for the cooling chiller)
  • The transmitter is not qualified for radiation environment and will be installed in the BGV racks (possibly inside the THMS PLC crate)


A PLC system is developed by Raphael Schlecht (TE-ABT-EC) to:

  • Acuquire the signals from the temperature and humidity sensors
  • Convert I/U to T (physical or dew point)
  • Provide the measurements to a FESA server
Documentation by Raphael:


A FESA class was developed for the BGV THMS PLC. Thanks to Marco Pimentel (TE-ABT-EC)! Currently the only functionality is to export the temperature and dew point measurements to Timber (no hardware control).
  • FESA Class name: BGV_THMS
  • FESA Device name: BGVDEMO.THMS.B2
  • FESA Server: ? (currently running on a TE-ABT computer)

The existing FESA classes can be explored with the "FESA3 Launcher" application. (how to launch it?)

Timber variables

In the Timber hierarchy, all variables related to the BGV Demonstrator are located in:
LHC -> Beam Instrumentation -> Beam Profile -> BGV Demonstrator

The temperature readings are of type integer. The Timber logging is made whenever there is a change >= 1 C. In addition, the values are logged every hour (even if there is no change).

The prefix BGVDA.A7L4.B2 is used for all BGV Demonstrator variables (see comment below).

Currently the following variables are logged:

PT100 probes

Timber variable name Name in BGV PLC Measured property
BGVDA.A7L4.B2:TEMP_CHM_WIN_AL Temp_Gas_1 T of Window chamber flange, Aluminium
BGVDA.A7L4.B2:TEMP_CHM_WIN_ST Temp_Gas_2 T of gas injection chamber flange next to Window, Steel
BGVDA.A7L4.B2:TEMP_CHM_CONE Temp_Gas_3 T of gas injection chamber, near the center/cone part
BGVDA.A7L4.B2:TEMP_DET_FTI Temp_Tent T inside the tent, near the Far-Top-Internal detector module

Humidity probes (Novasina)

Timber variable name Name in BGV PLC Measured property
BGVDA.A7L4.B2:NOVASINA_TEMP_MANIFOLD Sensor_1 Humidity sensor - Temperature in the Cooling Manifold
BGVDA.A7L4.B2:NOVASINA_DEWP_MANIFOLD Sensor_1 Humidity sensor - Dew point in the Cooling Manifold
BGVDA.A7L4.B2:NOVASINA_TEMP_TENT Sensor_2 Humidity sensor - Temperature in the Tent
BGVDA.A7L4.B2:NOVASINA_DEWP_TENT Sensor_2 Humidity sensor - Dew point in the Tent

Comment about the name BGVDA.A7L4.B2:
This name follows the standard Timber variable naming conventions used in the LHC. It is interpreted as follows:

  • BGVDA is a name used for the mechanical drawings related to the BGV Detector, model A
  • A7L4 is a bit more tricky. It could be interpreted as a vacuum sector, but this is not correct: the BGV Demonstrator is located in vacuum sector B7L4. Names like X7L4 are used in the LHC layout database to name subsystems / devices. The letter X is replaced by a letter A, B, C, ... depending on the location of the device with respect to the IP
  • Therefore, BGVDA.A7L4.B2 should be interpreted like: BGV detector system, subsystem located closest to the IP, measuring Beam 2
  • Although this prefix is not so useful for the people familiar with the BGV, it is a meaningful reference to the system and its location

Installation photos

Position of the THMS Junction box
(connect PT100 sensors to the multiwire long cables)

Slots for the PT100 probes on the BGV chambers

More BGV installation photos can be found here

THMS PLC crate in rack BY12 (occupies U3 to U8 inclusive)

More rack photos can be found here

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf 2015_05_21--HumidityMeasurement.pdf r1 manage 7526.0 K 2015-05-26 - 19:25 PlamenHopchev  
PDFpdf BGV_THMS_documentation.pdf r1 manage 118.8 K 2015-05-22 - 10:50 PlamenHopchev  
PDFpdf BGV_THMS_shematic.pdf r1 manage 78.6 K 2015-05-22 - 10:50 PlamenHopchev  
PDFpdf BGV_TempAndHumMeas_v0r4.pdf r1 manage 514.4 K 2015-03-20 - 13:22 PlamenHopchev  
PNGpng IMG_8216_THMS_Labels_Small.png r1 manage 2064.5 K 2015-03-20 - 15:08 PlamenHopchev  
JPEGjpg IMG_8275.JPG r1 manage 2557.4 K 2015-03-20 - 15:08 PlamenHopchev  
JPEGjpg IMG_8431.JPG r1 manage 2742.6 K 2015-03-20 - 15:08 PlamenHopchev  
PNGpng IMG_9152_labels_small.png r1 manage 1515.6 K 2015-05-22 - 10:55 PlamenHopchev  
PNGpng IMG_9158_cut_labels_small.png r1 manage 2393.7 K 2015-05-22 - 10:55 PlamenHopchev  
PDFpdf TempSensor_PT100_RS.pdf r1 manage 199.8 K 2015-03-20 - 13:38 PlamenHopchev  
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Topic revision: r5 - 2015-06-10 - PlamenHopchev
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