DIA TECH CAA uses the fact that certain impacts on material properties lead to increased concentration of dedicated gases within the generator cooling air circuit, which help to identify thermal or dielectric problems. The measurement furnishing for CAA (= Cooling Air Analysis) is exceptional and simple. It consists of air hoses, gas analyser, control equipment, computer and software as well as.
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CAA Measurement Scheme
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CAA Trend Display
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DIA TECH CAA-HS measures and analyses the hydrocarbon-gas concentration, which is emitted from the insulation material in case of overheating. The effect of bad or broken winding connections, which cause locally extraordinary high temperatures, can be detected in this way. DIA TECH CAA-HS is focused on soldered connections.
Problems to be detected:
- Faulty winding connections – break in worst case
The advantages of this method are:
- The simplicity of the installation (only hoses are to be installed)
- The simplicity of retrofitting at existing units
- The thermal monitoring of the entire winding system with one single measuring-point
Required soft- and hardware:
- Hydro carbon gas analyzer
- Pneumatic multiplexer (CAA MUX)
- Control equipment with control program (CAA data logger)
- Computer with diagnosis software
Main auxiliary parameter for diagnosis:
Long-term trend of CHn concentration (hot spot value) and humidity
DIA TECH CAA-O3 provides monitoring and evaluation of partial discharge activity on the surface of ground wall insulation from which conclusions can be drawn about dirt, changes of potential gradients, and insulation damage in the stator winding area.
Problems to be detected:
- Deterioration of isolating capability – flashover in worst case
The advantages of this method are:
- The simplicity of the installation (only hoses are to be installed)
- The simplicity of retrofitting at existing units
- The dielectric monitoring of the entire winding system with one single measuring-point
Required soft- and hardware:
- Ozone analyzer
- Combined humidity/temperature sensor
- Pneumatic multiplexer (CAA MUX)
- Control equipment with control program (CAA data logger)
- Computer with diagnosis software
Auxiliary parameters for diagnosis:
- Terminal voltage
- Stator current
- Humidity and cooling air temperature
Long-term trend of 03 concentration
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