All transformers are tested in compliance with IEC 60076-1 and IEC 60076-11
Routine tests
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
Type tests
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
Special tests
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.