Testing the HV circuit breakers of foreign manufacture using the SKB EP instruments
Fleet of circuit breakers of Russian manufacture is regularly updated. Nevertheless, preference is very often given to HV equipment of Siemens, ABB, and Areva. Switch gears designs often include foreign HV circuit breakers.
Tests of Russian circuit breakers of different types and brands using such SKB EP instruments as PKV/M6N, PKV/M7, PKV/U3 and PKV/U3.0 pose no problems: displacement transducers can be mounted on any types of circuit breakers thanks to special fasteners; instruments are easily adjusted to any measurements.
As to tests of SF6 circuit breakers of foreign manufacture using the SKB EP instruments, control of their speed characteristics and travel parameters was initially impeded by absence of special fasteners for mounting the displacement transducers. It is impossible to measure the travel and speed parameters of moving parts of a circuit breaker without the displacement transducer.
We performed a good deal of work to adapt displacement transducers to foreign circuit breakers design.
They were first experimentally tested together with specialists of SF6 equipment department of Elegazenergoservis LLC (Moscow) that deal with service support of SF6 equipment of all the voltage classes up to 500kV, and with pre-commissioning of SF6 equipment at newly built substations.
Practically in all the SF6 circuit breakers the shaft extension is accessible for transducer mounting. Manufacturers have already provided threaded connections M6, M8 or M10 for connecting the instruments. To mount a transducer on the shaft it suffices to use a special adapter.
A nip with a magnet ensures the transducer casing immobility during circuit breaker switching over. Rotary joint of a magnet balances axis misalignments. If drive design does not allow magnet installation on the circuit breaker frame (e.g., it is vertical) as is the case with the KRUE ELK drive of ABB firm, a special platform with G-clamps is used that can be mounted on the frame of any design.
For control of the Siemens dead tank SF6 circuit breakers of 3AP1 DT type, the DP21 transducer is mounted on the adapter. Manufacturer has provided the M8 threaded connection in the drive shaft. An adapter in screwed into this hole. A nip of a transducer is fastened to a special support.
Dependence of shaft rotation angle of such circuit breakers on the contacts travel is known to be linear one. Therefore, for the instruments adjustment for measuring the travel parameters of a particular circuit breaker it suffices to "calibrate" the transducer, i.e., to specify a table for rotation angle conversion into linear displacement.
Thus, SKB EP instruments can be used for control of all the required performances of modern SF6 circuit breakers (time and speed characteristics, travel parameters, currents of electric magnets, voltages, resistances of different rheostats, high solenoid currents, etc.).