Ultra-Fast Current Limiter (FCL): Isang Rebolusyonaryong Solusyon na May Milisegundo-Level na Pagkakawala at mga Benepisyo sa Ekonomiya

13yrs + staff 30000+m² US$100,000,000+ China

Panoramas: Pagbabago ng Bilis at Ekonomika sa Proteksyon ng Short-Circuit

Narito ang solusyon na nakatuon sa ultra-mabilis na short-circuit current limiting device, na disenyo upang lubusang tugunan ang lumalaking hamon ng labis na short-circuit currents at tiyakin ang kaligtasan ng mga power grid at kagamitan.

1.1 Puno ng mga Katangian

Ultra-Mabilis na Interruption Speed: Nakakadetekta ng mga pagkakamali at nag-limit ng current sa loob ng 1 millisecond, na mabisa sa pagsasala ng short-circuit current bago ito umabot sa inaasahang peak nito.
Malaking Interruption Capacity:

Suitable para sa 12kV/17.5kV systems: Maximum breaking capacity ng 210kA (RMS).
Applicable para sa 24kV/36kV/40.5kV systems: Maximum breaking capacity ng 140kA (RMS).

1.2 Puno ng mga Advantages

Economic Efficiency: Nag-ooperate sa parallel na may mga current-limiting reactors upang ibigay ang pinakamurang limiting solution. Ito ay nag-iwas sa pagpapalit ng buong switchgear panels o transformers dahil sa pagtaas ng short-circuit currents, na siyang nagpapababa ng investment sa mga bagong o upgraded substations.
Malawak na Compatibility: Ideal para sa interconnecting switchgear at substations; sa maraming scenario (halimbawa, parallel operation ng maraming transformers), ito ang tanging feasible na teknikal na solusyon.
Katangi-tanging Reliability:

Higit sa 60 taon ng global operational experience (naimbento noong 1955), na na-validate sa libu-libong proyekto sa buong mundo.
Ang statistics mula sa halos 4,000 units ay nagpapakita ng average operation frequency na isang beses lamang sa bawat apat na taon, na nagpapakita ng matatag at reliable na performance.

Mahalagang Technical Q&A

No.	Key Question	Core Answer
1	Ano ang peak short-circuit current?	Ang maximum instantaneous value sa unang cycle pagkatapos ng pagkakamali ng short-circuit, na resulta ng superposition ng periodic at non-periodic components. Ito ay nag-generate ng malalaking electromagnetic forces (testing dynamic stability) at init (testing thermal stability).
2	Bakit limitin ang peak short-circuit current?	Ang peak currents na lumampas sa equipment-rated withstand parameters ay maaaring masira ang switchgear, circuit breakers, current transformers, at cable connectors sa pamamagitan ng powerful na electromagnetic forces.
3	Paano mag-adapt sa parallel operation ng maraming transformers?	Para sa switchgear na may withstand capability ng 2Ik, sa system na may apat na transformers (4Ik) sa parallel, maari itong maperpektong madapt sa pamamagitan ng pag-install ng mabilis na current limiters sa pagitan ng bus sections (halimbawa, sa pagitan ng sections 1-2 at 3-4).
4	Ano ang tripping criteria? Paano iwasan ang false trips?	Ang control unit ay nag-monitor ng instantaneous current (I) at rate of current rise (di/dt). Ang trip ay triggered lang kapag ang parehong ito ay lumampas sa set thresholds. Ang dual criterion na ito ay naglalayong i-interrupt lamang ang hazardous na short-circuit currents, habang ang general faults ay na-handle ng downstream circuit breakers.
5	Paano i-maintain pagkatapos ng operasyon?	Ang core operating component (conductive bridge) ay may modular design at maaaring ibalik para sa repair. Kailangan lamang ng replacement ang internal conductive core, inductive filler, at parallel fuses; ang iba pang components ay reusable, na nagpapataas ng napakababang maintenance costs.

Puno ng mga Function at Value

3.1 Puno ng Function

Nag-detect at nag-limit ng mga pagkakamali sa initial rising stage ng short-circuit current (sa loob ng 1ms), na mabisa sa pag-iwas sa pinsala sa power equipment dahil sa kulang na dynamic at thermal stability. Ito ay perpekto na nag-compensate sa inherent limitations ng traditional circuit breakers—"mabagal na gumagana at hindi maaaring suppres ang first half-wave peak current."

3.2 Comparative Advantages

Comparison Object	Advantage Details
Traditional Circuit Breakers	Ang breakers ay nangangailangan ng tens of milliseconds upang interrupt, na hindi maaaring iwasan ang impact ng unang peak current. Ang limiter na ito ay tumutugon sa loob ng 1ms, na nag-restrict ng actual peak short-circuit current sa mas mababang level.
Current-Limiting Reactors	Iwasan ang voltage drop, active losses (copper losses), at reactive losses na kaugnay ng reactors sa continuous operation. Kasama rin dito ang pag-iwas sa generator regulation issues na dulot ng integration ng reactor.

3.3 Applicable Scenarios

Power plants
Malalaking industriyal na grid substations
Partikular na key circuits/scenarios: Transformer/generator feeder circuits, bus tie sections, reactor bypass applications, at interconnection points sa pagitan ng grids at captive power sources.

Structure at Design

4.1 Overall Composition

Ang three-phase AC system fast current limiter ay binubuo ng:

3 conductive bridge bases
3 conductive bridges
3 matching current transformers
1 control unit

4.2 Key Component Details

Component Name	Composition / Features	Key Parameters / Rules
Conductive Bridge Base	Includes mounting plate, insulators, pulse transformer, at connectors na may quick couplings	- Rated current ≥2500A at voltage 12/17.5kV: Bolted connections. - Pulse transformer: ≤17.5kV (installed only sa ilalim); ≥24kV (installed sa both top at ilalim para sa reliable isolation).
Conductive Bridge	Conductive core at inductive filler encapsulated sa insulating cover	Upon tripping, ang inductive filler ay triggered, driving ang conductive core to break rapidly sa pre-cut nito; ang current ay transfer sa parallel fuse.
Matching Current Transformer	Bushing o block type, series-connected sa main circuit	Features a gapped core (high overcurrent factor, low remanence) at shielded primary/secondary windings (low impedance) upang ensure ang measurement accuracy at speed.
Control Unit	Includes power supply, control, indication, at anti-interference units	- Dimensions: 600mm (W) × 1450mm (H) × 300mm (D); weight: 100kg. - Indication unit: 5 flag relays (3-phase trip indication + readiness monitoring + power supply monitoring).

Working Principle: Achieving 1ms Current Limiting

5.1 Core Composition

Ang device ay essentially an intelligent parallel combination ng dalawang components:

"Extremely fast switch (conductive bridge)": Carries rated current during normal operation at opens instantaneously during faults.
"High-breaking-capacity fuse": Ultimately interrupts the high current after the switch opens.

5.2 Operation Sequence

Detection: Matching current transformers (CTs) continuously collect current signals; ang control unit ay calculates instantaneous current (I) at rate of current rise (di/dt).
Judgment: Kapag ang parehong I at di/dt ay lumampas sa set values, ang control unit ay immediately issues a trip command (independent three-phase judgment at triggering).
Interruption: The trip capacitor discharges into the pulse transformer, triggering the inductive filler in the conductive bridge. This generates high-pressure gas, causing the conductive core to rupture at its pre-cut within 1ms.
Current Limiting: Arc resistance increases rapidly, transferring current to the parallel fuse. The fuse begins limiting within 0.5ms and extinguishes the arc completely at the next current zero, clearing the fault.

5.3 Auxiliary Units

Power Unit: Provides 150V DC power to charge the trip capacitor and supply electronic components. Includes a watchdog circuit to monitor system health.
Anti-Interference Unit: All external wiring passes through this unit, providing effective protection against external electromagnetic interference and preventing false operations.

Commissioning and Testing

6.1 Testing Requirements

Regular functional testing is required, which can be executed by users or ABB service engineers.

6.2 Dedicated Equipment

Simulator: Temporarily replaces the conductive bridge during testing. Its built-in neon lamp lights up upon receiving a trip pulse, indicating proper operation.
Test Plug & Test Instrument: Used to check trip output voltage and overall functionality. Features a user-friendly interface and easy operation (dimensions: 400×215×320mm; weight: 11kg).

Scope of Supply and Parameters

7.1 Supply Models

Model Type	Applicable Scenarios	Core Configuration
Discrete Components	For installation in existing switchgear	3 bases + 3 conductive bridges + 3 CTs + 1 control unit
Drawout Cabinet	For metal-clad switchgear	Conductive bridges mounted on withdrawable carts (with isolating switch function); CTs fixed; control unit installed in the low-voltage compartment
Fixed Cabinet	- For 12/17.5/24kV systems - Mandatory for 36/40.5kV systems	All components fixed inside the cabinet. For 36/40.5kV systems, the control unit is often installed in a separate control box.

7.2 Key Technical Parameters (Example: Discrete Components)

Note: ¹ indicates forced air cooling is required; compatible with 50/60Hz frequency.

Technical Parameter	Unit	12kV	17.5kV	24kV	36/40.5kV
Rated Voltage	V	12000	17500	24000	36000/40500
Rated Current	A	1250-5000¹	1250-4000¹	2500-4000¹	1250-3000¹
Rated Short-Circuit Breaking Current (Max.)	kA RMS	210	210	210	140

Typical Application Scenarios

Application Scenario	Core Issue	Solution Value
Parallel System Operation	Short-circuit current from multiple transformers in parallel exceeds switchgear ratings	1. Allows reduced system impedance, minimizing voltage drop. 2. Optimizes transformer load distribution, reducing losses. 3. Enables uninterrupted load transfer during faults, improving supply reliability.
Grid-Captive Power Interconnection	Captive generator operation causes excessive short-circuit current at the common coupling point	The only rational solution. Can be equipped with directional tripping (requires CT at generator neutral) to ensure operation only for grid-side faults.
Bypassing Current-Limiting Reactors	Reactors in continuous operation cause losses and voltage drop	Bypasses reactors during normal operation (zero loss, zero voltage drop); rapidly interrupts during short circuits, diverting current to the reactor for limiting.
Selective Application of Multiple Units	Selective operation required when multiple limiters are installed on multi-section buses	Uses "current vector sum" criterion to ensure only the limiter closest to the fault operates. Supports up to 5 transformers in parallel (using 4 limiters).