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Density Monitor TS

Density monitor for SF6 gas-insulated high-voltage circuit breakers

The gas density monitor TS continuously monitors the density of the insulating gas SF6. Up to five microswitches inside the device respond reliably to any decreases in the density and pressure of the SF6 insulating gas. The operating points can be set at the factory according to the customer’s requirements.


Key Features

  • Pressure range 0 to 10 bar relative
  • High switching accuracy and long-time stability
  • Rugged design (IP 10)
  • Up to 5 microswitches
  • Concentric pressure connector



The gas density monitor TS consists of the following principal components:

  • Aluminum housing and pressure connector
  • Electronic PCB with up to five microswitches
  • Reference gas bellow, filled with SF6 gas

Operating principle

The density monitor TS monitors gas density by way of a reference chamber filled with SF6 gas. The gas and reference chambers are separated by a metal bellows. A density and pressure difference between the two chambers deflects the metal bellows. The movement of the bellows is transmitted by a switch rod. A switch plate activates the microswitches whose purpose is to indicate a pressure drop.

The operating points for triggering the signal can be set at the factory according to the customer’s requirements by way of lockable screws (plungers). Up to five microswitches with changeover contacts can be installed in the housing. The microswitch contact outputs are taken to terminal tabs on the PCB. The use of vibration-resistant microswitches rules out any shock-induced chattering at the switching contacts.


The information on this website represents the state of knowledge at the time of writing. Technical specifications are subject to modifications. Comde-Derenda GmbH accepts no liability whatsoever for the content provided or for damages resulting from the use of its products.

Technical Data

Connection Flat plugs, 6.3 x 0.8 mm, IAW DIN 46244
Microswitches 3 to 5 included, max. 2.5 mm² IAW IEC 60947
Protection IP 10 IAW IEC 60529
Vibration stability > 4 g (20 … 80 Hz), 0.05 bar from switching point
Pressure range 0 … 10 bar rel. / 0 … 145 psi rel.
Hysteresis < 0.1 bar / 1.5 psi (typ.)
Switching accuracy ± 0.08 bar / 1.2 psi
Response threshold ± 0.05 bar / 0.7 psi
Reference chamber leakage rate < 0.005 bar/year (5 * 10-9 mbar * l * s-1)
Electric strength 2 kV (50/60 Hz) to ground
Rated surge voltage 5 kV (1.2/50 μs) to ground IAW IEC 61000-4-5
Electric switch rating,
Resistive load (inductive load)
AC 250 V, 10 (2) A
DC 250 V, 0.2 (0.2) A
DC 220 V, 0.25 (0.2) A
DC 125 V, 0.4 (0.25) A
DC 110 V, 0.5 (0.3) A
DC 60 V, 1.5 (0.4) A
DC 48 V, 1.9 (0.7) A
DC 24 V, 3.0 (2) A
Operating temperature –40 … +70 °C / –40 … +158 °F
Storage temperature –50 … +80 °C / –58 … +176 °F
Weight 380 g
Material pressure connection and tubular housing AISi1MgMn, anodized
Material reference gas bellows system Stainless steel 1.4541 (bellows) / 1.4301 (bellows housing)

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