A significant part of our business involves transformer diagnostics and measurements. ZREW Transformatory has the most modern measuring equipment, a fully equipped laboratory and experienced staff.
Advanced diagnostics of transformers
We offer the following diagnostic operations either on site on the customer’s premises or at a Testing Station:
Measuring and testing of transformers including, among other things:
- winding resistance measurements,
- ratio measurement and a check of connection groups,
- magnetising current measurement,
- measuring dispersion reactance,
- measurement of the dielectric loss factor tan δ and the capacity of transformer windings,
- measurement of the dielectric loss factor tan δ and bushing capacities,
- measurement of winding insulation resistance and dielectric absorption coefficients R60/R15,
- measurement of zero sequence impedance,
- vibroacoustic transformer analysis,
- measurement of load losses and short-circuit voltages,
- measurement of losses and no-load current,
- induced voltage test,
- applied voltage test,
- impulse voltage test,
- partial discharge measurements by an acoustic method,
- partial discharge measurements by an electrical method,
- acoustic pressure measurements,
- mechanical testing windings by the SFRA method,
- computer testing of OLTC change times,
- moisture testing of fixed insulation by the FDS, PDC and RVM methods,
- thermal-imaging measurements,
- testing of OLTC (measuring asynchronicity in the opening of contacts, measuring the continuity of the selectors cage),
- testing the power consumption of drives in OLTCs.
Testing insulating oils
Testing the physical and chemical parameters of insulating oil provides valuable information on the degree of moisture and aging of a transformer’s insulation. The insulating oil’s dielectric as well as physical and chemical properties are significantly affected by the operating conditions: temperature, oxygen from the atmosphere, the load applied and the construction materials.
To ensure reliable operation of equipment it is important to maintain the parameters of the oil at the appropriate level, which requires control testing of these parameters.
Tests of insulating oils involve the following:
- determining the furan derivatives in the oil,
- content of PCB,
- water content by the K. Fischer method
- the voltage of a sudden flow of current through the insulator,
- dielectric loss factor tan δ
- flash point,
- acid value,
- density at 20° C
- kinematic viscosity,
- testing the surface tension of the oil,
- the content of impurities,
- testing the degree of polymerisation of new and used papers,
- determining the active sulphur content
- testing the degree of aging of the insulation oil and determining its surface tension and polarity factor,
- chromatographic analysis of gases dissolved in the oil (DGA).
The great advantage of transformer diagnosis based on DGA is that it does not require shutting the unit down. This makes it possible to:
- detect latent defects in the active part,
- monitor the development of damage in time,
- take appropriate remedial measures early.
Measurements of electrical installations and devices:
- examining the effectiveness of fire protection,
- earthing resistance measurements,
- periodic testing of electrical devices,
- testing of OHS equipment up to 400 kV (insulating rods, gloves, dielectric shoes).
tel. +48 42 671 86 50
fax: +48 42 671 86 52