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K1650 Alternator
Purge Gas Monitor for Hydrogen Cooling of Turbo-generators in Power
stations |
Application
Modern turbo-generators, as used in power stations, produce a
great deal of heat which must be dissipated. The preferred coolant is hydrogen
gas 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 turbo-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 analyser 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.
System Description
The display/controller unit and the remote sensor
assembly are shown below. 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.
Technical Specification
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K1650 Alternator Purge Gas Monitor for Hydrogen and Carbon Dioxide
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Display |
Dot-matrix LCD
showing four lines of alphanumeric characters |
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Thermal conductivity ranges and gas types
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0 to 100% CO2
in Air (Resolution 0.5%)
0 to 100% H2 in CO2
(Resolution 0.1%)
90 to 100% H2 in Air (Resolution
0.1%) |
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Accuracy |
± 1% of span
(typically) |
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Speed of response (typical) |
T90 = 5secs. |
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Sample connections |
Captive seal compression fittings suitable for
0.25inch (or 6mm) outside diameter tube. |
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Sample pressure |
Set by vent pressure which must be nominally
atmospheric |
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Sample flow |
100 to 300ml/min for
optimum performance |
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Sample temperature |
-10 to +60°C
(non-condensing) |
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Outputs |
4 to 20mA, proportional to the selected range.
Maximum load 600Ω |
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Ambient temperature |
-5 to 40°C |
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Power Requirements |
110/120V or 220/240Vac, 50/60Hz power
consumption, 12VA |
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Alarms |
Four user configurable alarms programmable for
level, function and hysteresis are provided as follows:
1 alarm for CO2 in Air
1 alarm for CO2 in H2
2 alarms for H2 purity
Outputs are volt-free changeover relay outputs contacts rated at 48Vac or
dc, 0.5A |
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Case Mounting |
Electronics unit: Control/Display unit: panel
mounting by four corner screws.
Remote sensor unit: wall/bulkhead |
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Download a full
specification (pdf)
For more information, please contact
Technical Sales
who would be delighted to discuss your needs |
