Purpose and principle of operation :
Device is intended for recording of fast transient processes (atmospheric (lightning) overvoltages). Device records amplitude, its duration and time of origin of voltage increase above maximum permissible operation voltage of electrical network. Device performs actual automatic calculation of insulation reserve of electrical network equipment (residual withstand) using recording of fast transient processes and building integral characteristics of overvoltages according to the character of recorded transient processes and utilizing evaluation algorithm of the influence of qualitative parameters of records to the status of electrical network (insulation reserve). Implemented evaluation algorithm of insulation reserve compares total integral characteristics of overvoltages and maintenance time of equipment with insulation test (limit) voltages of equipment.
Technical characteristics :
- Supervision of integral overvoltage characteristics (insulation reserve) according to the character of recorded transient processes;
- Sampling step 50-100 ns;
- Number of recorded transient processes – 50;
- Number of analyzed transient processes – unlimited;
- „on-line“ integral evaluation of insulation reserve caused by influence of overvoltages;
- Transmission of information – Ethernet;
- Smart algorithm for actual supervision of insulation reserve of electrical network equipment.
Measurement range :
- Phase voltages 0 – 250 V
- Phase currents (can be measured) 0,05 – 100 A
- Zero sequence voltage 5 – 300 V
- Measurement frequencies up to 10 MHz
- Measurement duration for analysis of single record up to 500 ms
Device is very useful for electrical utilities and industry since enables more precise forecast and planning of repairing and preventive maintenance works as well as optimally allocate financing to perform these works. It is very relevant to use the device in industry for supervision of insulation of electric motors and generators since insulation of this equipment ages 2 times faster than other electrical equipment. Overvoltage recorder constantly supervises quality of protection of electrical network by surge arresters (their protective characterics deteriorate with time) and respectively helps to ensure safety of electrical network.
Based on device records of overvoltages in 6-10 kV cable network with isolated neutral and duration histograms it is possible to determine the level and duration of overvoltages affecting insulation and forecast preventive tests of the cables.
- reliable recording of overvoltages;
- supervision of change of reserve of residual withstand of insulation of electrical network equipment;
- forecast and planning of repairs or need of preventive maintenance.
Device is connected to phase outputs and circuit of open delta of voltage transformer.