Experimental measurements and investigations

Based on wide experience of various investigations in medium-voltage networks, LLC BOLID can provide experimental investigations in 6-35 kV networks with the development of the following recommendations for the purpose of no-failure operation of the 6-35 kV equipment at single line-to-ground faults and when switching it by vacuum circuit breakers, and increasing of power supply reliability:

  • Power supply circuit analysis and development of the programme on experimental investigations.
  • Experimental investigations of neutral displacement voltage, taking into account harmonic components in neutral voltage, and determining of capacitance current at single line-to-ground faults by indirect measurements using a resonance curve.
  • Experimental investigations of single line-to-ground currents and line-to-ground voltages at artificial solid grounds in 6-35 kV networks, regardless of neutral grounding conditions. Digital oscillography of voltage and current signals. Evaluation of the efficiency of the compensation system and resistors by artificial single line-to-ground arcing faults.
  • Measurements of power quality (quality of electrical energy), including harmonic composition of voltage, in 6-35 kV networks under normal operating conditions with ERIS-KE.02 (Energy Calculation and Information System, Power Quality.02 ) for compliance with requirements of GOST 13109-97.
  • Processing and analysis of investigations, including determination of harmonic composition for single line-to-ground current. Determination of the current level of compensation at sections with ground fault neutralizers (GFN). Considerations about installed GFN and necessity of new additive GFN installation, with given recommendations about proper equipment specifications.
  • Experimental investigations of overvoltages when switching a high-voltage circuit breaker (e.g. vacuum circuit breakers) in various network nodes. Determination of switching overvoltage levels on the basis of obtained oscillograms, with further mathematical simulation of transient processes when switching a high-voltage circuit breaker.
  • Determination of time and velocity characteristics of high-voltage circuit breakers with PKV/M7 (PKV/M7 is an instrument of high-voltage circuit breaker controlling).
  • Development of recommendations on effective overvoltage protection when switching feeders with motor and transformer loads by high-voltage circuit breakers, and recommendations on increasing of equipment reliability.

LLC BOLID instruments of control and measurements in 6-35 kV networks:

  • Multi-channel digital oscilloscopes and recorders Yokogawa DL750 Scope Corder (produced by Yokogawa Electric Corporation, Japan).
  • Voltage dividers 10-35 kV (produced by LLC BOLID) with 20 MHz – 2,5 MHz bandwidth and voltage ratios from 3500 to 18000 for transforming of original (input) voltage signal under transient and steady-state conditions.
  • Portable high-voltage circuit breaker control instrument PKV/M7 (produced by SKB EP, Irkutsk, Russia) handling near the circuit breaker which is to be controlled. It is used for determination of time and velocity characteristics of SF6, oil and vacuum circuit breakers in close, open, and close-open operations.
  • Micro & Milli ohmmeter RET-MOM (produced by NPP Dinamika, Cheboksary, Russia). It is a combined instrument which measures electric resistance of motor, transformer and tripping device windings, and contact resistance, including transient resistance of main contacts of high-voltage circuit breakers.
  • Portable Energy Calculation and Information System ERIS-KE.02 (produced by Energocontrol, Moscow, Russia). It is used for registration of power quality parameters in three-phase networks (three-, four-, and five-wire networks) and evaluation of power quality parameters for compliance with requirements of GOST 13109-97.
  • Current transducer LT-500 using the Hall effect.