NTT’s TechCheckTM is our basic package of tests that provides regularly scheduled analysis of insulating fluid for gas generation and specific physical properties.
This custom service, conforming to IEEE suggestions, provides regular condition reports which can supplement or eliminate some costly maintenance procedures. It combines both Gas Chromatography and physical analysis methods.
This service is especially intended for transformers, load tap changers, and oil-filled circuit breakers.
NTT TechCheckTM can be combined with numerous ASTM tests to suit your particular diagnostic and fault detection needs.
Shipments of New Mineral Oil as Received from the Refinery
When mineral insulating oil is received in the field for installation in electrical equipment, it should be checked for certain key values that may be affected by shipping/handling and storage.
New Oil Processed for Equipment Prior to Filling 345kv and Above
In this procedure, oil samples are taken before the oil enters into the electrical equipment. The object is to fill high-voltage equipment with oil that contains the very least amount of particulate material and water, recognizing that a slight reduction in quality due to contact with the equipment insulation and other material will occur.
New Oil Received in New Equipment by Voltage Class
Mineral Oil that has been shipped within new equipment from the manufacturing plant and sampled at the installation site.
New Oil in Equipment After Filling and Standing Immediately Prior to Energizing
Test limits are provided for oil in equipment after processing and standing prior to energizing.
Continued Use of Service-Aged Insulating Oil by Voltage Class
Suggested test limits by voltage class for oils in power transformers to remain in continued service.
Oil to be Reconditioned or Reclaimed
Oils that do not meet the suggested limits for continued use in their respective voltage classes may be considered for reuse in similar apparatus at a lower voltage class or may be conditioned for continued use.
New Minerial Oil
Oil received in the field ready for installation should be checked for certain key values that may be affected by shipment and storage.
New Oil After Processing and Filling Immediately Prior to Energizing
Just as in power transformers, oil samples are taken before the oil enters into the electrical equipment. Tests limits are given for oil after being processed, placed in equipment and allowed to stand for some time before energizing.
Continued use of Service-Aged Insulating Oil
Suggested test limits for oil-filled circuit breakers to remain in continued service. Some users, however, recondition or change their oils without testing them after a preset number of operations.