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TALLATION OF EHV TRANSFORMER
IN EXTREMELY HUMID WEATHER
CONDITION – A CASE STUDY OF MOISTURE
MANAGEMENT
DEBAL BANERJEE, SAKYASINGHA MAITI
ASSET CREATION GROUP
Abstract
In today’s competitive scenario, it is essential to keep reinventing our business processes time to time as
per requirement. Technology adoption is one of the survival tools that can put us in the cutting edge. Power
Transformer Installation is not an exception either. The challenge has become harder due to few inevitable
reasons – Increased Single Unit Value of Power Transformers of higher ratings, Techno-Commercial borderline
design from manufacturers, necessity for speedy execution of Installation & Commissioning Process etc.
are premier of them. In addition, with our proven installation practices, we have adopted few contemporary
technologies in order to minimize absorption of detrimental moisture by Solid Insulation of active parts of
EHV Transformers. Application of ‘Dry Air’ during installation, supported by ‘Dew Point & Relative Humidity
Monitoring’ is an e ective process of dehydrating Core Coil Assembly of an EHV Transformer in its nascent
stage. These processes are also recommended by reputed Transformer Manufacturers, other expert bodies like
IEEE, CBIP, IEEMA and standards like IS:10028, IEC: 60076, etc. This paper describes how we have customized
this contemporary technology for Dehydration of Core-Coil Assembly into our recent installations of 220 kV, 160
MVA, Oil Immersed Cable Box Type Auto Transformer at Prinsep Street Substation, which we had to install &
commission under extremely moist weather condition.
Index Terms: Core Coil Assembly, Extra High Voltage, Relative Humidity, High Voltage, Intermediate Voltage,
Low Voltage
INTRODUCTION main tank. ‘Pyrolysis’ caused by the heat generated
within the winding, ‘Oxidation’ caused by the amount
Health of a power transformer is determined by the health of oxygen present inside the main tank and most
of its solid insulation. Hydrolysis has the more devastating importantly ‘Hydrolysis’ caused by the moisture inside
effect on the solid insulation than Pyrolysis & Oxidation. the transformer. The final aging rate is the resultant
of all the above-mentioned degradation processes
Decay of the solid insulation is the effect of three (Figure 1 & 2).
different processes that takes place inside the
39
IN EXTREMELY HUMID WEATHER
CONDITION – A CASE STUDY OF MOISTURE
MANAGEMENT
DEBAL BANERJEE, SAKYASINGHA MAITI
ASSET CREATION GROUP
Abstract
In today’s competitive scenario, it is essential to keep reinventing our business processes time to time as
per requirement. Technology adoption is one of the survival tools that can put us in the cutting edge. Power
Transformer Installation is not an exception either. The challenge has become harder due to few inevitable
reasons – Increased Single Unit Value of Power Transformers of higher ratings, Techno-Commercial borderline
design from manufacturers, necessity for speedy execution of Installation & Commissioning Process etc.
are premier of them. In addition, with our proven installation practices, we have adopted few contemporary
technologies in order to minimize absorption of detrimental moisture by Solid Insulation of active parts of
EHV Transformers. Application of ‘Dry Air’ during installation, supported by ‘Dew Point & Relative Humidity
Monitoring’ is an e ective process of dehydrating Core Coil Assembly of an EHV Transformer in its nascent
stage. These processes are also recommended by reputed Transformer Manufacturers, other expert bodies like
IEEE, CBIP, IEEMA and standards like IS:10028, IEC: 60076, etc. This paper describes how we have customized
this contemporary technology for Dehydration of Core-Coil Assembly into our recent installations of 220 kV, 160
MVA, Oil Immersed Cable Box Type Auto Transformer at Prinsep Street Substation, which we had to install &
commission under extremely moist weather condition.
Index Terms: Core Coil Assembly, Extra High Voltage, Relative Humidity, High Voltage, Intermediate Voltage,
Low Voltage
INTRODUCTION main tank. ‘Pyrolysis’ caused by the heat generated
within the winding, ‘Oxidation’ caused by the amount
Health of a power transformer is determined by the health of oxygen present inside the main tank and most
of its solid insulation. Hydrolysis has the more devastating importantly ‘Hydrolysis’ caused by the moisture inside
effect on the solid insulation than Pyrolysis & Oxidation. the transformer. The final aging rate is the resultant
of all the above-mentioned degradation processes
Decay of the solid insulation is the effect of three (Figure 1 & 2).
different processes that takes place inside the
39
