SGS is the world’s leading inspection, verification, testing and certification company. SGS is recognised as the global benchmark for quality and integrity. With more than 95,000 employees, SGS operates a network of over 2,400 offices and laboratories around the world. In this exclusive interaction with T&D India, we have Nagraj Ranganathan, Business Director – Oil, Gas and Chemicals, SGS India Pvt Ltd, expounding on the capabilities of SGS in the niche field of transformer oil testing.
What is the role of oil in a transformer and why should this oil be tested?
Transformer oil serves as a coolant, insulator in electrical power transformer and dissipates the heat of the transformer. It provides electrical insulation between the various energized parts and acts as a protective coating layer to prevent oxidation of the metal surface.
During voltage fluctuations, the temperature of the windings in transformer surges. Transformer oil acts like a coolant in these conditions and reduces the temperature of the windings.
Buchholz Relay acts as a conservator in the transformer; this device operates with the level of oil in the transformer. This way oil prevents severe losses and damage to transformer.
This transformer oil should be tested for the following reasons:
- Transformer oil acts as a health indicator for the device.
- Insulating oil may deteriorate owing to the accidental seepage of water, chemical decomposition, oxidation, contamination by gases, electrical and thermal stress, physical contamination.
- Both chemical as well as electrical conditions of the transformer can be monitored by testing the oil on a periodic basis.
- Testing transformer oil samples for degradation of the products can provide useful information about the nature and severity of possible faults inside a transformer
- It helps in determining internal thermal fault and detecting condition of paper insulation
What are the various tests performed by SGS on transformer oil? Are there any international standards that transformer oil needs to adhere to?
The physical properties are tested by a series of tests that include: Electric Strength (BDV);
Water Content (PPM); Neutralization Value (Acidity); Dielectric Dissipation Factor (Tan Delta); Specific Resistance (Resistivity); Interfacial Tension Test (IFT); Flash Point Test; Total Sludge Test; Appearance; Density; Pour Point; Kinematic Viscosity; Corrosive Sulphur; and SK Value Test.
The special (or diagnostic) tests include: Dissolved Gas Analysis (DGA); Furan Analysis (Furanic Compounds); Polychlorinated Biphenyl (PCB) Content; Oxidation Stability; Gassing Tendency; Presence Of Oxidation Inhibitor (Antioxidant Additives); Total Sulphur Content; Potentially Corrosive Sulphur; Metal Content.
All said tests adhere to various standards according to the specific requirements. The test specifications are: IS 335; IS 866; IEC 60296; IEC 60422; ASTM D3487
Of late, transformers using “ester oil” have also been pressed into operations. Though ester oil is bio-friendly, is there any concern over adherence to standards or efficiency of the transformer?
As per various studies conducted by various institutions, Ester oils offer several advantages, including biodegradability, higher flash point, higher thermal conductivity, lower calorific value and higher temperature stability. Consequently, it is now considered that ester-based oils offer better benefit-to-cost ratios than mineral oil.
However there are still a lot of researches and comparative studies being undertaken and it is early to remark about any concerns regarding this.
Constant monitoring of the transformer health by testing the transformer oil is thereby a very critical area, and this presents a vast scope in India
We understand that SGS also carries out testing and certification in the field of power distribution. Please tell us about the scope of your services.
SGS caters to various industries, markets and offers different services through its several verticals. Apart from testing, we have undertaken a number of projects (including internationally funded ones) to certify the quality of project execution. These cover several projects wherein the scope starts from preliminary survey till the final commissioning of the project.
Activities like supplier/vendor assessments, third party inspections, QHSE audits, test witness, pre-shipment, loading inspections, expediting services and surveillance services can be provided during Engineering and Procurement phase of any project.
Civil work supervision, supervision during assembly, erection and testing of mechanical equipment, electrical devices, instrumentation, control systems, etc., Commissioning survey, start-up test supervision of equipment and systems, QHSE supervision & monitoring, technical staffing services may be offered during construction phase.
Would you like to discuss any important (completed) assignment in India in the field of power distribution?
SGS has provided key recommendations to customers after undertaking procedures of Dissolved Gas Analysis (DGA). Post implementation, the DGA was rechecked and the gas concentrations were decreased.
SGS has also completed field quality service and supply inspection services for transmission lines projects for various clients.
The power transmission and distribution (T&D) sector is witnessing unprecedented investment. Given this, how do you see the scope for SGS in India, especially in the two areas of transformer oil and power distribution?
Infrastructure is a key driver for sustained growth of an economy and power is a critical component of infrastructure. India’s power sector is one of the most diversified in the world. It has witnessed significant developments not only in generation and transmission capacity addition, but also in distribution reforms. This sector accounts for a significant percentage of the total investment inflows into the country.
The industry landscape presents ample of scope for TIC companies especially in testing and quality certification domains. SGS is the world’s leading company with proven expertise and technical breadth to comprehensively cater to the specific requirements of this industry.
Uninterrupted power supply in power distribution systems requires prevention of failures, and breakdowns. Constant monitoring of the transformer health by testing the transformer oil is thereby a very critical area, and this presents a vast scope in India – not only for testing of transformer oil – but also diagnostic testing on transformers.
