Transformers are some of the most expensive power system assets and have long delivery times for replacement in case of failure. PowerSafe provides a compete compliment of transformer services including installation supervision, testing, commissioning and maintenance.
Power transformers travel long distances to get from their location of manufacture to the customers site. Receiving inspections are performed at point of customer offloading to ensure no damage to the transformer occurred during transport, normally required for quality control purposes, insurance and/or manufacture warranty. Typical receiving inspections performed include general overall inspection and check of components delivered, measurement of moisture within the tank, check of core and clamp insulation, and performance of a sweep frequency response analysis (SFRA) to assess mechanical condition of the transformer.
Power transformer are tested in the field after installation and before first energization, as part of planned maintenance, or after unplanned trip events. PowerSafe provides transformer testing services; both basic (turns ratio, phase displacement, winding resistance, power factor and capacitance for bushings and windings, excitation current, insulation resistance, current transformer tests) and advanced tests (Sweep Frequency Response Analysis, Dielectric Frequency Response, Frequency Response of Stray Losses, Short Circuit Impedance and Dynamic Resistance for OLTCs).
ON LOAD TAP CHANGERS (OLTCs) are used to provide voltage and/or phase shifting control by providing the regulating action under load without interruption to the power supply. There are numerous types of switching technologies and designs in use today depending on the vintage, make and model of the equipment. Inspections, maintenance and overhaul of tap changers at the recommended interval is critically important to prevent failure which could possibly jeopardize the transformer to which the tap changer is connected to. PowerSafe has the knowledge and experience to perform inspection and overhaul on a variety of makes and models of OLTCs, new and old. Complementing our knowledge and experience of OLTCs we can perform oil handling duties, perform on site oil dielectric testing, perform electrical tests such as transformer turns ratio per tap, winding / contact resistance per tap and dynamic contact resistance measurements.
The filling process for large power transformers requires specialized handling procedures and high vacuum oil purification equipment, these are necessary to ensure the transformer is oil filled without air voids in the insulation system and the moisture level within the transformer is at an acceptable level.
Transformers are designed to provide many years of trouble free service but that doesn’t mean they don’t require attention. PowerSafe takes the worry out of annual inspections by performing these inspections and providing clients with a detailed record. Routine tasks performed during annual inspections include check of cabinet heaters, oil sampling, general overall inspection, thermal imaging scan, check of auxiliary gauges and components, and inspection of control cabinets.