At substation maintenance sites, it is common to encounter switch characteristic testers that fail to operate due to mismatched operating power supplies, or test data that jumps due to electromagnetic interference. The GIS combined apparatus switch characteristic tester with a built-in DC operating power supply integrates the operating power supply and the test unit, reducing external power connections, but its maintenance has specific requirements.
Comparison with discrete test schemes
In traditional schemes, the tester and the DC operating power supply are configured separately, requiring on-site connection to a DC panel or carrying a battery pack. There are many wiring points, and reverse polarity or voltage drop can easily cause circuit breaker refusal to operate. The GIS combined apparatus switch characteristic tester with a built-in DC operating power supply directly outputs the DC power supply for circuit breaker operation, eliminating external cables and simplifying wiring. However, note that the instrument can only use the dedicated power cord specified for this product and compliant with the product specifications; it must not be replaced arbitrarily, otherwise output accuracy may be affected or the internal power module may be damaged.
Daily maintenance points
This instrument is used to measure mechanical dynamic characteristic parameters of high-voltage circuit breakers such as vacuum, SF6, minimum oil, and bulk oil types. The stability of its internal DC power supply directly affects the measurement of opening and closing coil current waveforms and operating times. During maintenance, the insulation layer and plug of the dedicated power cord should be checked regularly to avoid bending or moisture. After long-term storage, it is recommended to first power on with no load and observe whether the power output indication is normal before connecting the circuit breaker. When strong electromagnetic interference is present at the test site, ensure the instrument is reliably grounded and kept away from interference sources such as primary busbars.
Selection considerations
Design and selection personnel can verify the rated output capability of the built-in power supply according to the operating voltage and current range of the circuit breaker under test. The instrument complies with the relevant requirements of GB1984 "High-voltage alternating-current circuit-breakers," and with speed/distance sensors it can complete mechanical characteristic tests. If GIS combined apparatus needs to be tested, confirm that the test line length and interface form adapt to the on-site layout.
