GMP Periscope – Gas Analysers

Monitoring the presence and evolution of gases dissolved in insulating oil of high voltage equipment such as power transformers and reactors, is an effective tool for diagnosing its operation conditions.

However, measurements of these gases in the laboratory, through tests of gas-chromatography in oil samples collected periodically can allow a problem to start and evolve to a failure during the period between samples, usually several months if not years.

Treetech’s GMP Sensor fills this gap by providing real-time monitoring of hydrogen dissolved in insulating oil. Hydrogen is considered a key gas for the detection of defects in equipment immersed in oil.

The GMP performs measurement without cross interference from other gases such as carbon monoxide, in order to obtain maximum sensitivity in detecting defects so that changes in hydrogen concentrations are not obscured by constant and/or elevated CO.

The GMP measures moisture and gases dissolved in insulating oil, communicating signs of:

• Hydrogen (H ) dissolved in the oil and its development trend, with a prediction of time to alarms;
• Percentage  of water saturation  (H2O ) in oil and associated  oil temperature;
• Water content (ppm) in the insulating oil at current temperature and at reference temperature,  both calculated through water saturation;
• Alarms for concentrations  of  H2  and H2O  high or very high, and for trends of increased  concentration  of H2  and H2O;

• Autonomous equipment. It has a display and indicators (LEDs) for measurement and configuration. The use  of the SDG or IDG HMI is optional;
• RS-485  communication systems for monitoring or supervision systems;
• Open protocols   Modbus   RTU or DNP3 Level 1 with support for 1ms resolution time-stamp;
• Robust design, exceeding the EMC standards for operation in substations with severe electromagnetic conditions.
• Operating temperature  -40  to 85 ºC, suitable for severe operating regimes and ambient conditions;
• Universal Power Supply, 38 to 265  Vdc or Vac;
• 4 programmable output relays;
• 2 current loop (mA) programmable outputs;
• Self-diagnosis of the condition of the sensor;
• IP-65 Protection Degree, withstands severe conditions for field exposed to the weather.

Operating Principle

• The sensors used by the Periscope to measure gas and moisture concentration use semiconductor technology, which eliminates cross-sensitivity to other combustible gases.
• The hydrogen dissolved in the oil represents the general status of the transformer.
• For the measurement of dissolved hydrogen to be effective for diagnosis of the equipment, the oil must be in contact with the GMP sensor.