E, SCF, JC — medium-voltage current-limiting fuses
Current-limiting fuses of series E, SCF and JC for protecting transformers, capacitors and motors in medium-voltage switchgear. They interrupt a short-circuit current within a half-cycle, and the peak arc voltage does not exceed twice the rated voltage. The fuses comply with JEC-2330 and JIS standards.
- Types
- general-purpose SCF and HF…E (full-range); back-up from 12 kV; JC-6/5…JC-6/100 for LBS
- Overload interruption
- 200–300% of rated current (general-purpose)
- Short-circuit interruption time
- within a half-cycle
- Peak arc voltage
- less than twice the rated voltage
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The main objects of protection are power transformers, capacitor banks and medium-voltage motors. The fuses are installed on their own or together with load break switches without a trip unit, for example LBS and LB. This scheme dispenses with an expensive circuit breaker with relay protection, so the cubicle is cheaper. The manufacturer makes two kinds of fuses, general-purpose and back-up, which differ in the range of currents they can interrupt. Both kinds are current-limiting, that is, they cut off a short-circuit current before it reaches its peak value.
The general-purpose fuses SCF and HF…E are full-range. They interrupt any overcurrent from the minimum melting current to the rated breaking current, and operate clearly at an overload of 200–300% of rated current. At large fault currents the element blows quickly. Since the fuse works across its whole breaking range, it can be used without a circuit breaker with a trip unit, saving on cubicle construction.
Back-up fuses are designed for a voltage of 12 kV and above. They are used together with circuit breakers that have a trip unit with a current transformer or an overcurrent relay. In this scheme the fuse takes the large short-circuit currents, while the breaker with the relay handles the smaller overcurrents. The choice between the two kinds depends on whether the cubicle has a circuit breaker with a trip unit.
The short-circuit current is interrupted within a half-cycle, so the requirements for the thermal and dynamic withstand of the protected equipment are substantially reduced. The peak arc voltage during interruption stays below twice the rated voltage, which excludes damage to the winding insulation of motors and other equipment. The fuse element of special design does not age over a long service life, and the operating characteristics repeat consistently.
For LBS load break switches, fuses JC-6/5…JC-6/100 are supplied. They are ordered separately as a set of three, with the rating specified in the order. The rating is chosen by the current and type of the protected equipment. The fuses comply with the requirements of JEC-2330 and JIS standards, which widens their field of application. By purpose, the series is regarded as an analogue of ПКТ 6–10 kV fuses, but the rating, voltage and cartridge dimensions for a specific cubicle are checked separately.
Technical specifications
| Types | general-purpose SCF and HF…E (full-range); back-up from 12 kV; JC-6/5…JC-6/100 for LBS |
|---|---|
| Overload interruption | 200–300% of rated current (general-purpose) |
| Short-circuit interruption time | within a half-cycle |
| Peak arc voltage | less than twice the rated voltage |
| Standards | JEC-2330, JIS |
Request a price and lead time
E, SCF, JC — medium-voltage current-limiting fuses. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
How do general-purpose fuses differ from back-up fuses?
SCF and HF…E interrupt any overcurrent from the minimum melting current to the rated breaking current, including overloads of 200–300%. Back-up fuses for a voltage of 12 kV and above work together with a circuit breaker that has a trip unit with a CT or a relay.
Which fuses are needed for the LBS load break switch?
Fuses JC-6/5…JC-6/100 are supplied for the LBS. They are ordered separately as a set of three, with the rating specified.
What can replace ПКТ 6–10 kV fuses?
By purpose, series E, SCF and JC correspond to these fuses for 6–10 kV networks. Final selection by rating, voltage and cartridge dimensions is made together with the manager.
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