ABB has launched an advanced transformer diagnostic service that uses state-of-the-art electronic equipment
ABB has launched an advanced transformer diagnostic service that uses state-of-the-art electronic equipment, operated by highly skilled and experienced test engineers, to provide utility and industrial customers with a fast, non-invasive, internal health check for power transformers up to 400kV. The service, designed to help keep transformers from any manufacturer operating at maximum load and energy efficiency, without compromising reliability or safety, can be applied at any stage of the asset’s life, from installation and commissioning, or as part of a condition based asset maintenance programme, right through to diagnosing and locating a potential problem - before it becomes a serious fault.
The transformer diagnostic service utilizes three main techniques – SFRA (Sweep Frequency Response Analysis), FDS (Frequency Domain Spectroscopy and winding resistance measurement:
SFRA
The SFRA (Sweep Frequency Response Analysis) test, carried out by a Pax FRAX-101 system, diagnoses the condition of the transformer windings and magnetic core. It is performed by injecting a variable frequency AC voltage to each winding and plotting the responding current as a curve. Typically, these ‘finger print’ reference curves are captured either when the transformer is new or when it is known to be in good condition. They can be used as a baseline reference during maintenance tests or when there is a reason to suspect a problem. In the hands of ABB’s team of transformer test experts the SFRA test is an excellent way of checking for movement or displacement of windings and can even locate the exact position of a fault.
FDS
FDS (Frequency Domain Spectroscopy), carried out by a Pax IDAX-206 system, is used to assess the integrity of a transformer’s insulation system by measuring its dielectric properties as a function of frequency over the range from 1 mHz to 1000 Hz. This test provides information about the volume of moisture and presence of contaminants in the solid insulation, as well as the conductivity and power factor of the oil.
Winding resistance measurement
The Omicron CPC 100 winding resistance measurement equipment is used to inject a DC current of up to 2kV through the transformer windings and it then measures the voltage drop across that winding to enable the resistance to be calculated. This test helps to check that the transformer connections are correct and that there are no severe mismatches or open circuits.
Liam Warren of ABB’s UK power service operation said: “Power transformers are mission-critical for many of our industrial, utility and power generation customers. Should a failure occur then it can result in a lengthy downtime, with consequent loss of operating revenue, and expensive repairs. Planned maintenance is the best insurance against transformer failure and that’s where this new service comes in. It offers an efficient, cost-effective way of assessing the overall condition of a transformer fleet so that areas of potential concern can be flagged and action taken well before a potential failure develops into a serious fault.
“Furthermore, if a customer has a transformer that is already causing concern, then our diagnostic team can establish the severity of the problem, locate the fault and provide expert advice on what action to take. For example, with regular testing it might be possible for the transformer to continue in service, while operating under a safe, reduced load, until a planned service interval is reached. Then ABB can provide a comprehensive repair and refurbishment service to restore the transformer to full working order.”
About ABB
ABB (www.abb.com) is a leader in power and automation technologies that enable utility and industry customers to improve performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 113,000 people.