HHA-BC high-voltage fuse-links for protecting capacitor banks
HHA-BC are high-voltage current-limiting fuse-links for protecting power capacitors and capacitor banks in medium-voltage networks. The fuse-links withstand inrush currents of up to 100 times the rated current on switching on and break short-circuit currents. They are used in 6–36 kV reactive power compensation installations.
- Purpose
- protecting MV power capacitors and capacitor banks
- Voltage selection
- fuse-link rated voltage above the voltage across it after operation, up to 2.5 × operating voltage
- Current selection
- fuse-link rated current at least 1.6–2 times the operating current of the capacitor
- Inrush currents
- up to 100 × rated current on switching on
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Capacitor banks are used for reactive power compensation, for improving the power factor and for reducing the distortion caused by harmonics. Connecting them to a medium-voltage network requires a well-thought-out protection scheme, because capacitors are sensitive to damage and, if operating conditions are violated, can cause significant losses. HHA-BC fuse-links are intended for this purpose.
Operating principle. HH fuse-links are connected in series with the switching device and the capacitors and protect first of all against short circuits, internal capacitor faults and external short circuits. Overload protection is usually provided by the built-in mechanical devices of the capacitors themselves. Capacitive circuits produce extreme inrush currents; on energization they often reach 100 times the rated current. This places high demands on the breaking capacity and the time-current characteristic of the fuse-link. It must on no account operate on capacitive currents in normal operation, otherwise restriking of the arc and damage are possible. The selection depends on several factors, so the final ratings are agreed against the time-current characteristic.
Selection rules. The rated voltage of the fuse-link must exceed the maximum voltage that can appear across its contacts after operation, often up to 2.5 times the operating voltage. The rated current is taken as at least 1.6–2 times the operating current of the capacitor, so that the fuse-link withstands inrush currents and higher harmonics without damage. VDE standards, for example VDE 0636, are designed primarily for inductive circuits and do not take into account capacitive currents with a power factor below 0.1, so special fuse-links under IEC 60549 are used. The final ratings are verified against the time-current characteristic of the fuse-link.
Protection schemes differ by region. In Europe, MV capacitors have built-in fuses to isolate faulty phases, and the busbars are protected by sectional fuse-links. In the USA, individual protection of each capacitor by an external fuse prevails. Full-range fuse-links or HH fuse-links with a striker and temperature limiter are suitable for it; the striker gives a mechanical signal through an auxiliary contact to trip the main device. Field of application: 6–36 kV reactive power compensation installations at substations, in industry and at renewable energy facilities, and filter-compensation units.
Technical specifications
| Purpose | protecting MV power capacitors and capacitor banks |
|---|---|
| Voltage selection | fuse-link rated voltage above the voltage across it after operation, up to 2.5 × operating voltage |
| Current selection | fuse-link rated current at least 1.6–2 times the operating current of the capacitor |
| Inrush currents | up to 100 × rated current on switching on |
| Variants | full-range fuse-links; with striker and temperature limiter |
| Standards | IEC 60549, IEC 60282-1 |
Request a price and lead time
HHA-BC high-voltage fuse-links for protecting capacitor banks. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
What inrush currents do capacitor fuse-links withstand?
Capacitive circuits often produce inrush currents of up to 100 times the rated current on switching on. The fuse-link must withstand them without damage and must not operate on capacitive currents in normal operation.
How do I select the rated voltage and current of the fuse-link?
The fuse-link voltage must exceed the voltage across its contacts after operation, often up to 2.5 times the operating voltage. The rated current is taken as at least 1.6–2 times the operating current of the capacitor.
What standards apply to capacitor fuse-links?
IEC 60549 for the protection of power capacitors and IEC 60282-1. VDE standards such as VDE 0636 do not take into account capacitive currents with a power factor below 0.1.
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