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 main purpose of the "Transformers" Laboratory is 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