RENAR and LOVAG accredited reference laboratory

The activity of high voltage equipment tests within ICMET Craiova is carried out in a laboratory equipped with the latest measurement techniques. These allow the complex verification of power transformers, instrument transformers and high voltage equipment. We perform both type tests and special tests, in full compliance with international standards.

Since 1995, the laboratory has been accredited by the Romanian Accreditation Association – RENAR (member of ILAC and EA) in accordance with the IEC / ISO 17025 standard. We also operate as a LOVAG (Low Voltage Agreement Group) Registered Laboratory, which confirms the global recognition of our competence.

• Download RENAR Accreditation Certificate (PDF)
  
• Download the Annex to the Accreditation Certificate (PDF)
  
• View document LOVAG Registered Laboratory (PDF)
  

Laboratory Infrastructure

The testing facility is composed of three main areas, sized for oversized equipment:

• Shielded high voltage chamber: With impressive dimensions (48 mx 32 mx 27 m), it is intended for special and type tests. Here are located the 4.2 MV impulse generator, the 1.2 MV transformer cascade, the DC rectifier and the artificial rain equipment.
• Induced voltage chamber: Space dedicated to routine tests (36 mx 32 mx 27 m).
• Outdoor testing ground: External platform (30 mx 35 m) used for reliability tests at extreme stresses.

Testing equipment and technical capabilities

We have high voltage sources capable of simulating extreme dielectric stress conditions:

1. Pulse generator (4.2 MV; 336 kWs)

• Lightning impulse voltage test: Up to 4200 kV (energy 336 kWs) and 700 kV (energy 4.9 kWs).
• Switching impulse test: Voltages up to 2600 kV and 300 kV.

2. Applied alternating voltage sources (25 Hz – 150 Hz)

• In the screened hall: Up to 1200 kV (current 1.2 A).
• Outdoor: Up to 1800 kV (current 1.2 A).
• At 50 Hz: 200 kV (0.5 A) and 350 kV (0.75 A) sources.
• Resonant system: 3 units x 250 kV (total 750 kV) at 1 A.
• Three-phase system (25-150 Hz): Voltages of 15 kV, 35 kV, 110 kV (Power 5 MVA, time 2 min).

3. DC power source

• Continuous voltage test: Up to 1100 kV (current 30 mA).

Advanced measurement techniques

To ensure accuracy during the sessions high voltage equipment tests, we use high-performance measurement systems:

• High voltage measurement system: Consists of a voltage divider and a peak voltmeter.
• Calibrated pulse dividers:
  • Lightning and switching impulse divider (643/4200 pF/kV) mounted with the generator (according to IEC 60060-2/94). Response time: 10 ns.
  • Resistive lightning impulse divider (10/2200 kΩ/kV). Response time: 27 ns.
  • Resistive lightning impulse divider (10/770 kΩ/kV). Response time: 10 ns.
• Capacitive AC dividers:
  • 160/1200 pF/kV (mounted with the cascade in the hall).
  • 200/1800 pF/kV (mounted with outdoor cascade unit).
• Analysis and recording:
  • Reference system (according to IEC 60-2) for LI, SI, AC, DC and impulse load for DP measurements, with traceability to PTB (Germany).
  • Specialized equipment for recording transient phenomena (10 bits, 100 MS/s, 3 channels).
  • Partial discharge (PD) measurement system using electrical and ultrasonic methods, with free PD sources up to 500 kV.
• Environmental monitoring: Equipment for measuring atmospheric conditions during tests.

Services offered

The laboratory performs the following types of tests in the shielded hall or at the assembly site:

• Full-wave (1.2/50 µs) and back-cut wave (2-8 µs) voltage impulse tests up to 4200 kV.
• Switching impulse tests up to 2600 kV.
• Tests with applied voltage (25-150 Hz) up to 800 kV.
• Single-phase and three-phase induced voltage tests (5 MVA).
• Continuous voltage tests up to 1200 kV (30 mA).
• External insulation tests under artificial rain (for equipment up to 400 kV).
• Measurement of partial discharges (electrical and ultrasonic method) and radio disturbances.
• Combined voltage tests: LI-AC, SI-AC, DC-LI, DC-SI.
• On-site services: Partial discharge measurement of power transformers at the installation site.

Reference list:

Download the document

Contact details

For commercial or technical requests, please contact the laboratory manager.

Responsible for testing: Eng. Laurentiu Vladoi
Phone: +40 351 404 888; +40 351 404 889
Fax: +40 351 404 890
E-mail: vladoilaurentiu@icmet.ro

Published works

The expertise of our specialists is validated by numerous papers published at international conferences in the field (CIGRE, ISH, ICATE).

Period 1995 – 1999

• A.Marinescu, I.Dumbrava, "Numerical method for plotting frequency characteristics of power transformers", First National Symposium on "High Current and High Voltage Tests. Measurements and Qualification of Electrical Equipment", Craiova 26-29 September 1995.
• A.Marinescu, I.Dumbrava, "On-line pressure, temperature and humidity measurement in HV Laboratory", Symposium Proceedings "Present State and Tendencies in EMC and HV Engineering", Bucharest November 1997.
• A.Marinescu, A. Ungureanu, I.Dumbrava, "Step response evaluation for voltage divider using numerical methods", International Conference of Applied and Theoretical Electronic ICATE'98 Craiova University.
• A.Marinescu, A. Ungureanu, I.Dumbrava, "Approximating Polynomials for d(U) Characteristics of IEC 52", CIGRE 33-99 (WG 03), 25 IWD, Weggis, Switzerland.
• A.Marinescu, G. Georgescu, V.Filisanu, "Checking and Calibration Proposal for Ultrasonic Transducers used by PD Measurement at Power Transformers", CIGRE 33-99 (WG 03), 26 IWD, Weggis, Switzerland.
• I. Dumbrava, "The selection of a digital system for recording high voltage impulses according to CEI 61083-1", The 6th National Symposium of High Voltages Technique TTI'99, Bucharest 28-29 October 1999.
• A. Marinescu, I. Dumbrava, "Using of frequency characteristics of input admittance of a power transformer to diagnose its mechanical and electromagnetical state", The 6th National Symposium of High Voltages Technique TTI'99, Bucharest 28-29 October 1999.

Period 2000 – 2002

• A. Marinescu, G. Georgescu, T. Nicoara, "Calibration of Acoustic Emission Transducers used to detect PD in Paper-Oil Insulation", Proc of 2nd Int. Symposium on Advanced Topics in Electrical engineering ATEE-2000, Bucharest 2000.
• A. Marinescu, Th. Vascan, D. Popa, A. Ungureanu, Fl. Urzica, I. Badea, "Tests of HV DC Underground and Submarine Cables", Symposium "50 years of electric power education in UPB", vol.1, paper 1.43, p.247-252, 10-11 Nov. 2000, Bucharest.
• A. Marinescu, D. Popa, Th. Vascan, A. Ungureanu, Fl. Urzica, "Some Problems linked to Dielectric Stresses Measurement at HV DC Cables Tests", CIGRE WG 33/03, 13 IWD, 2000, Dresden, Germany.
• A. Marinescu, E. Marinescu, G. Georgescu, V. Filisanu, "Gas in Oil Global Detection by Ultrasonic Method", CIGRE WG 33/03, 14 IWD, 2000, Dresden, Germany.
• A. Marinescu, "Measurement of Acoustic Emission Generated by PD in Paper-oil Insulation of power and instrument transformers", Workshop in the framework of Cooperation Research Project ROM 99/006, April 2002, Karlsruhe, Germany.
• A.Marinescu, A. Ungureanu, I.Dumbrava, D. Popa, Th. Vascan, "Mobile Calibration System for High Voltages", METSIM'2002, 27-28 June 2002, Bucharest.
• A. Marinescu, E. Marinescu, "A Direct Method for On Line Monitoring of Clamping Axial Forces in HV Power Transformers", CIGRE WG 33-03 40 IWD, 2002, Ludvika, Sweden.
• A.Marinescu, "Monitoring System for Large Power Transformers", CIGRE WG 33-03 41 IWD, 2002, Ludvika, Sweden.