Mechanical short-circuit indicators (rotor and fluid) for MV cables and busbars
Mechanical short-circuit indicators in two versions, rotor and fluid, for cables and busbars of medium-voltage distribution networks. The devices work without batteries or an external power supply and show the passage of a short-circuit current by color. They are installed on taps and in transformer substations where remote signalling is not needed.
- Rotor — I>> setting
- 150–2000 A (factory setting); delay 100 ms; ±10 %
- Rotor — reset
- manually with a stick
- Fluid — I>> setting
- 400, 600, 1000 A; delay 200 ms (100 ms on request); ±20 %
- Fluid — reset
- automatic after 6–8 h
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The indicator is installed directly on a cable or busbar in the cubicle, so it is easy to add to equipment that is already installed. Operation is caused by the magnetic field that the short-circuit current induces in the monitored conductor. A yoke made of ferromagnetic steel concentrates this field, and when the current reaches the I>> setting, the mechanism switches over. The housing and fixing screws are made of polyamide, and the operating temperature range is −40…+85 °C. The devices need no maintenance during their service life. For retrofitting, no secondary circuits need to be laid, because the device has neither a battery nor an external power supply.
The rotor version (Rotor indicator) has a rotating rotor with a colored field. Black means that the indicator has not operated, red shows that a short-circuit current has passed through the conductor. The setting is made at the factory within 150–2000 A, the operating delay is 100 ms at the nominal setting value, accuracy ±10 %. The fault is recorded even when voltage is re-applied to the line. The indicator is reset manually with an insulating hook stick that is included in the delivery.
The fluid version (Fluid indicator) is built on a transparent flask with liquid and red particles. During a short circuit the magnetic field lifts a stirrer, the particles rise, and the flask turns red. After 6–8 hours they settle, and the indication disappears by itself, without a crew call-out. Factory settings are 400, 600 or 1000 A, delay 200 ms at the nominal setting (100 ms on request), accuracy ±20 %.
Both devices are intended for cable branch lines and MV transformer substations where local visual indication is sufficient. During a round, operating personnel see through which cubicles the fault current has passed, and thus narrow the search section. Mechanical indicators are also installed next to the electronic indicators of the Sigma and ComPass series as an additional visual signal in case the electronics have lost power or need checking. The choice between versions depends on the operating mode. The rotor version has a wider range of settings and a more precise threshold, and the fluid version resets itself and does not require a repeat trip to the substation.
Technical specifications
| Rotor — I>> setting | 150–2000 A (factory setting); delay 100 ms; ±10 % |
|---|---|
| Rotor — reset | manually with a stick |
| Fluid — I>> setting | 400, 600, 1000 A; delay 200 ms (100 ms on request); ±20 % |
| Fluid — reset | automatic after 6–8 h |
| Housing | polyamide, yoke of ferromagnetic steel |
| Temperature | −40…+85 °C |
| Power supply | not required (no batteries) |
Request a price and lead time
Mechanical short-circuit indicators (rotor and fluid) for MV cables and busbars. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 9030 33 70 00 |
|---|---|
| HS, 6 digits | 9030 33 |
| CN (EU) | 9030 33 70 |
| HTSUS (USA) | 9030 33 38 00 |
| China customs tariff | 9030 33 90 00 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
What operating current settings do the mechanical indicators have?
The rotor indicator is set at the factory within 150–2000 A with ±10 % accuracy. The fluid indicator is supplied with a setting of 400, 600 or 1000 A, accuracy ±20 %.
Do the indicators need a power supply or battery replacement?
No. Both versions operate from the magnetic field of the short-circuit current and work without batteries in the range −40…+85 °C.
How is the indication reset after a fault?
The rotor indicator is reset manually with the insulating hook stick from the delivery. The fluid indicator resets itself after 6–8 hours, when the particles settle in the flask.
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