All transformers are tested in compliance with IEC 60076-1 and IEC 60076-11
Below the list of routine tests to be performed on dry-type transformers:
- Measurement of winding resistance
- Measurement of voltage ratio
- Checking of phase displacement
- Measurement of short-circuit impedance and load loss
- Measurement of no-load loss and current
- Dielectric routine tests (please check below according to the Um (IEC 60076-3))
- Insulation test and functional verification of accessories
- Tests on on-load tap changers, where appropriate
- Auxiliary wiring insulation test
- Check of the ratio and polarity of built-in transformers
- Measurement of partial discharges
Below the list of type tests that can be performed on dry-type transformers:
- Temperature-rise type test (IEC 60076-2)
- Dielectric type tests (IEC 60076-3)
- Determination of sound level (IEC 60076-10) for each method of cooling for which a guaranteed sound level is specified
- Measurement of the power taken by the fan
- Measurement of no-load loss and current at 90% and 110% of rated voltage
Below the list of special tests that can be performed on dry type transformers directly in SEA or in our associated laboratories:
- Dielectric special tests (IEC 60076-3)
- Winding hot-spot temperature-rise measurements
- Determination of capacitances windings-to-earth and between windings
- Measurement of dissipation factor (tan δ) of the insulation system capacitances
- Determination of transient voltage transfer characteristics
- Measurement of zero-sequence impedance(s) on three phase transformers
- Short-circuit withstand test
- Measurement of d.c. insulation resistance between each winding to earth and between windings
- Measurement of frequency response (Frequency Response Analysis or FRA); the test procedure shall be agreed between manufacturer and purchaser
- Check of external coating (ISO 2178 and ISO 2409 or as specified)
- Determination of weight with transformer arranged for transport for transformers up to 1,6 MVA by measurement; for larger transformers by measurement or calculation as agreed between manufacturer and purchaser
- Detection of harmonic content in no load current
- Thermographic detection of hot-spots
- Measurement of winding inductance
- Recurrent voltage surges test
- In-rush surges test
- Verification of the environmental classes
- Verification of the climatic classes
- Verification of the behaviour to fire classes
- Low temperature test
- Measurement of the transmitted vibrations
- Test on vibration floor (seismic)
The type and/or special tests that can be carried out on the transformers are always listed separately both in phase of offer and/or order.
Other tests requirements for specific transformers are specified in IEC 60076-3
Archive of type tests
SEA has a large archive of type and special tests carried out on many dry-type transformers that can be consulted by its customers.
Some examples of test performed on cast resin transformers:
Toxicity tests by Breda Scientific Institute
In compliance with the test methods provided by CEI 20-37 on a cast resin sample, a toxicity percentage lower than 0.1% has been recorded for gases released during combustion.
Fire behaviour test performed by CESI
This test has been carried out on a sample composed by a complete leg (core, LV and HV windings) of a 1600 kVA transformers.
Various tests on insulating materials
Samples made of the same used resin for the autoestinguishing test have been analized by IMQ.
Low temperature tests
Thermal cycle test has been carried out and passed at CESI (4 cycles from -20 °C to +20 °C in 24 hours).
Thermal shock test at -50 °C has been carried out and passed at Magrini's lab.
- Dynamic short circuit withstand test
Several certificates of dynamic short circuit tests carried out on transformers with different powers and voltages have been performed at CESI.