Thermal Conductivity Gas Analyzer for Alternator Purge (Panel Mount) - K1650
- Certified for hazardous area use
- Compact self-contained unit with remote sensor
- Low cost and easy to install
- Simple, low cost maintenance
- User-friendly interface
Modern powerplant generators, turbogenerators, and turbine generators as used in power stations, produce a great deal of heat which must be dissipated. The preferred method of cooling is hydrogen cooling which has a cooling capacity of around seven times that of ambient air. It is essential that the hydrogen remains uncontaminated by air leakage or a potentially explosive gas mixture can result. Air in-leakage also increases the viscosity of the hydrogen and therefore its friction with the rotor, increasing the losses within the system. Before either filling with hydrogen or re-filling with air, it is necessary to use an inert intermediary gas to avoid creating a flammable mixture. Carbon Dioxide (CO2) is the gas most commonly used for this. Thus, for filling the generator, air is first purged from the system with CO2 and then the CO2 is purged out with hydrogen. The Alternator Purge Gas Monitor measures all stages of the hydrogen filling and air re-filling processes as well as the hydrogen purity during normal operation.
Principle of Operation
The Alternator Purge Gas Monitor uses the proven katharometer sensor used in the Hitech K1550 analyzer range. In construction the katharometer comprises two chambers, each with an identical thermal conductivity sensor. One chamber is sealed and is filled with a reference gas and the other receives the sample gas. The difference in thermal conductivity of the reference and sample gases is translated into a concentration figure by the microprocessor circuitry within the electronics unit. The inherent stability of this system and, its almost perfect temperature compensation, make the instrument one of the most accurate available.
The display/controller unit and the remote sensor assembly are shown overleaf. Designed to be fitted into the turbo-generator cubicle, the display module plate mounts the control electronics and the intrinsically safe barriers. Depending on the scale selected from the keypad, the display will show one of the three following measured values. 0 to 100% CO2 in Air 0 to 100% H2 in CO2 90 to 100% H2 in Air Four user programmable alarm relay outputs are provided and their status is displayed on LED's on the front of the module. The remote sensor assembly consists of a katharometer supplied in a wall mounting, IP65 enclosure complete with flowmeter and sample flow control valve. The sensor is certified to European standards for use in Group IIB + H2 gases, and the zener barrier interface, incorporated in the display/controller unit, allows 'live-working' on the sensor unit.