Hybrid Gas Density Monitor 878X – Hybrid Gas Density Monitor

Mechanical and electronic monitoring


  • Exact switching following isochore at all temperatures
  • No contact bouncing
  • Independent, galvanically separated circuits
  • Continuous analogue output signal for gas density
  • Long term drift free output signal
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Technical Data


High voltage switchgear


Hybrid gas density monitors

Measuring principle

Mechanical monitoring: Principle: Reference gas measurement
Electronic monitoring: Principle: Oscillating quartz measurement

Approval / conformity

Ex according to standards, IEC/EN 60079-0 /-11/-26, EN 50303


At min. 5 kPa distance from switch point no contact bouncing
under 20...100 Hz: 4 g

Pressure connections

1/4" NPT m, 1/2"NPT m, G1/4" f, G1/4" m, G1/2" m, G1/2" m frontal membrane, G1/2" m flush membrane

Media temperature

-40°C ... 80°C


50g/ 8 ms

Electrical connections

EN175301-803-A; M12x1; MIL-C 26482; Binder 723; Cable

Ambient temperature

-40°C ... 80°C

Type of protection

II 1G Ex ia IIC T3 ... T6 Ga
II 1D Ex ia IIIC IP6x T145 ... T70°C
I M1 Ex ia I



Output signal

Mechanical monitoring: floating change-over contact
Electronic monitoring/Sensor: analogue: 6.5...20 mA current loop
Output signal 6.5...20 mA
current loop 0...0.85MPa absolute SF6 @ 20°C 0...56.1 kg SF6 /m3

Measuring range

Mechanical monitoring, measuring range absolute: 0...1.1 MPa (0...1100 kPa)
Electronic monitoring/sensor, measuring range absolute: 0...0.85MPa SF6 @ 20°C 0...56.1 kg SF6 /m3

Dielectric strength

Microswitch: 2 kV terminal ground
Output signal sensor: 250V against mass (EN60255-5)


1.4435, 1.4404, 1.4571 (AISI316L, AISI316)

Hybrid Gas Density Monitor 878X - Hybrid Gas Density Monitor