Ultra-Fast Current Limiter (FCL): Isang Mapagpalit na Solusyon na May Kakayahan ng Pagsasara sa Antas ng Milisegundo at mga Benepisyo sa Ekonomiya

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

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

Nagtutuon ang solusyong ito sa isang ultra-mabilis na device para limitahan ang short-circuit current, na disenyo upang talakayin nang pundamental ang lumalaking hamon ng labis na short-circuit currents at tiyakin ang kaligtasan ng mga power grid at kagamitan.

1.1 Pundamental na Katangian

Ultra-Mabilis na Bilis ng Pagsasara: Nakakadetect ng mga kapansanan at limitado ang current sa loob ng 1 millisecond, na mabisa na pinipigilan ang short-circuit current bago ito umabot sa inaasahang peak.
Malaking Kapasidad ng Pagsasara:

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

1.2 Pundamental na Advantages

Ekonometrikong Efisyensiya: Nag-ooperate sa parallel sa mga current-limiting reactors upang magbigay ng pinakamurang limiting solution. Ito ay nakakaiwas sa pagpapalit ng buong switchgear panels o transformers dahil sa tumataas na short-circuit currents, na malaki ang pagbawas sa investment sa bagong o upgraded substations.
Malawak na Katugmaan: Ideal para sa interconnecting switchgear at substations; sa maraming mga scenario (halimbawa, parallel operation ng maraming transformers), ito ang tanging feasible na teknikal na solusyon.
Katangi-tanging Reliability:

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

Pangunahing Teknikal na Q&A

No.	Pangunahing Tanong	Pundamental na Sagot
1	Ano ang peak short-circuit current?	Ang pinakamataas na instantaneous value sa unang cycle pagkatapos ng short-circuit fault, na resulta ng superposition ng periodic at non-periodic components. Ito ay nagbibigay ng napakalaking electromagnetic forces (testing dynamic stability) at init (testing thermal stability).
2	Bakit limitahan ang peak short-circuit current?	Ang peak currents na lumampas sa equipment-rated withstand parameters ay maaaring sirain ang switchgear, circuit breakers, current transformers, at cable connectors sa pamamagitan ng powerful na electromagnetic forces.
3	Paano sumunod sa parallel operation ng maraming transformers?	Para sa switchgear na may withstand capability na 2Ik, sa isang sistema na may apat na transformers (4Ik) sa parallel, maari itong mapuno ng perpekto 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 maling trips?	Ang control unit ay nagmo-monitor ng instantaneous current (I) at rate of current rise (di/dt). Ang trip ay naitrigger lamang kapag ang parehong ito ay lumampas sa set na threshold. Ang dual criterion na ito ay nagtiyak na ang mga hazardous na short-circuit currents lamang ang maiinterrupt, habang ang mga pangkaraniwang faults ay hahandle 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 palitan ang internal conductive core, inductive filler, at parallel fuses; ang ibang components ay reusable, na nagpapataas ng napakababang maintenance costs.

Pundamental na Functions at Value

3.1 Pundamental na Function

Nakakadetect at limitado ang mga kapansanan sa initial rising stage ng short-circuit current (sa loob ng 1ms), na mabisa na pinipigilan ang pinsala sa mga power equipment dahil sa kulang na dynamic at thermal stability. Ito ay perpektong nagpapabuti sa inherent limitations ng traditional circuit breakers—"mabagal na aktwal at hindi maaaring pigilan 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, hindi maaaring iwasan ang impact ng first peak current. Ang limiter na ito ay sumasagot sa loob ng 1ms, na limitado ang 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 and 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	Kasama ang 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 at the bottom); ≥24kV (installed at both top and bottom for reliable isolation).
Conductive Bridge	Conductive core at inductive filler na encapsulated sa isang insulating cover	Upon tripping, ang inductive filler ay naitrigger, na nagdradrive ng conductive core upang mabilis na bumreak sa kanyang pre-cut; 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 tiyakin ang measurement accuracy at speed.
Control Unit	Kasama ang 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 esensyal na isang 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; the control unit calculates instantaneous current (I) and rate of current rise (di/dt).
Judgment: When both I and di/dt exceed set values, the control unit immediately issues a trip command (independent three-phase judgment and 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).