The innovative Sverker 900 test set, which has been conceived as an engineer’s “multi-function testbox” for protection testing. It features an intuitive user interface so that a PC is not required to operate the instrument.
It centres around a touchscreen that provides access to a wide range of pre-configured virtual test instruments, allowing the required test function to be selected quickly and easily. Full manual control and configuration are also supported and, in addition to the touchscreen, the instrument is provided with a large rotary knob that can be configured as required to control the current and voltage generators.
To make the Sverker 900 into a truly versatile “testbox”, additional tools are provided. These include an analogue ammeter and an analogue voltmeter, together with facilities for measuring a wide range of parameters such as phase angle; active, reactive and apparent power; power factor; resistance; reactance and frequency.
Other virtual instruments include a prefault-fault instrument, a ramping instrument and a sequence instrument. An impedance instrument is also provided, which allows relays to be tested directly from the impedance plane with conversion from impedance to voltages and currents carried out automatically by the test set. There is also a CT magnetisation instrument available. Test configurations and test results are stored in internal non-volatile memory and can be readily transferred to and from a PC via the instrument’s USB port.
In developing this innovative solution, key factors the designers took into account were the need for modern distribution relay protection schemes to be tested by three-phase secondary injection and also the requirement for test sets to provide high-power, high-amplitude outputs for use on high burden relays or when carrying out single-phase tests on current and voltage transformers.
The requirement for high-power single-phase test capabilities is addressed by making provision for connecting the three-phase current and voltage generators in series or parallel, as appropriate. This is by no means an unusual arrangement, but it is can involve a tangle of flexible connecting leads with plenty of scope for making wrong connections.
The Sverker 900 uses rigid links to make the necessary connections and the sockets for the links are positioned in such a way that it is physically impossible to make the wrong connections. These simple yet novel ideas allow convenience to be combined with safety and speed.
