The quality control includes:
Incoming quality control of all materials and accessories.
- All materials undergo different types of incoming quality control. Materials essential for the overall quality of our products undergo tests in the company testing laboratories.
Quality control during manufacturing.
- During the manufacturing process all stages are monitored according to approved by the top management Quality plan.
End control and testing.
- All transformers undergo routine tests according to IEC 60076, IEEE or other international standard as specified by the client.
- On client’s demand by the client additional special and type tests are performed.
- All tests are performed on-site in HHIB testing laboratories, except short circuit withstand.
- The transformer short circuit withstand capability is proved by means of calculations.
- On client's demand the tests can be performed in internationally acknowledged independent laboratories such as KEMA - Holland, CESI - Italy, ICMET - Romania.
The Transformer Laboratory is accredited according to ISO 17025 with the following scope: to perform all routine, type and special tests required by international or local standards or requested by the customer.
The laboratory includes two separate sections - "High Voltage" section and "Transformers" section. A "Generator hall" provides both sections with voltages with frequency of 50, 60 and 200 Hz.
The following tests can be performed in the respective sections
- Turn-ratio measurement and phase displacement:
- DC resistance of the windings
- No-load losses and harmonics in no-load current
- Short-circuit impedance and load losses
- Zero-sequence impedance
- Heat-run test and power consumption of cooling system
- Sound-level and vibrations measurement
- Watt balance test
- C and power factor measurements of the insulation
- Insulation resistance
- Oil breakdown voltage measurement
- Lightning Impulse voltage test including chopped wave
- Switching Impulse voltage test
- Separate source AC withstand voltage test
- Induced overvoltage test
- Partial discharges measurement
- Transients transferred through the windings
The Transformer Laboratory is accredited according to ISO 17025 with the following scope: to perform all routine, type and special tests required by international or local standards or requested by the customer for OLTCs.
- Full wave lightning impulse test (LI)
- Chopped wave lightning impulse test (LIC)
- Switching impulse test (SI)
- Applied voltage test (AV)
- Measurement of partial discharges