Internal Oil-immersed Secondary circuit breaker
For 35MM mounting hole size Completely Self-Protected(CSP) Oil immersed Distribution Transformers.
Ketrans CSP Internal oil-immersed secondary circuit breakers are protective devices installed inside the transformer tank. Positioned between the low-voltage winding and the secondary bushing terminals, they monitor transformer load current and automatically disconnect the circuit during overload or short-circuit conditions.
Key Features:
- Installed inside the transformer for compact and integrated protection
- Provides overload, short-circuit, and over-current protection
- Bi-metal and magnetic tripping mechanisms for fast response
- Optional signal light contact and emergency control setting
- Reliable performance under oil-immersed conditions
- Suitable for three-phase or single-phase distribution transformers
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625 Single Phase 1F Circuit Breaker – Flat [35mm]- Model: T2P625T110
- Rated Current: 625A
- For Transformer: 150KVA
- Rated Voltage: 240V
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625 Single Phase 1F Circuit Breaker – Curved [35mm]- Model: T2P625T110
- Rated Current: 625A
- For Transformer: 150KVA
- Rated Voltage: 240V
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700 Single Phase 1F Circuit Breaker – Curved [35mm]- Model: T2P700T110
- Rated Current: 700A
- For Transformer: 167KVA
- Rated Voltage: 240V
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700 Single Phase 1F Circuit Breaker – Flat [35mm]- Model: T2P700T110
- Rated Current: 700A
- For Transformer: 167KVA
- Rated Voltage: 240V
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2X313 Three phase 3F Circuit Breaker-Flat [35mm]- Model: T3P2X313T110
- Rated Current: 626A
- For Transformer: 225KVA
- Rated Voltage: 208V/120V
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2X313 Three Phase 3F Circuit Breaker-Curved [35mm]- Model: T3P2X313T110
- Rated Current: 626A
- For Transformer: 225KVA
- Rated Voltage: 208V/120V
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2X420 Three Phase 3F Circuit Breaker-Curved [35mm]- Model: T3P2X420T110
- Rated Current: 840A
- For Transformer: 300KVA
- Rated Voltage: 208V/120V
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2X420 Three Phase 3F Circuit Breaker-Flat [35mm]- Model: T3P2X420T110
- Rated Current: 840A
- For Transformer: 300KVA
- Rated Voltage: 208V/120V
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520 Single Phase 1F Circuit Breaker – Curved [35mm]- Model: T2P520T110
- Rated Current: 520A
- For Transformer: 125KVA
- Rated Voltage: 240V
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520 Single Phase 1F Circuit Breaker – Flat [35mm]- Model: T2P520T110
- Rated Current: 520A
- For Transformer: 125KVA
- Rated Voltage: 240V
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Working Principle of Internal Oil-immersed Secondary Circuit Breaker
The breaker connects between the transformer’s low-voltage winding and secondary bushings. When current exceeds the rated value, the bimetal element heats and bends, triggering the trip mechanism. In case of short circuit, the magnetic trip device reacts instantly, disconnecting the transformer from the load and preventing damage.
Advantages of Oil-immersed Internal Circuit Breakers
Oil immersion provides excellent insulation and cooling, allowing the breaker to operate reliably under heavy load conditions. The internal installation design reduces external wiring, minimizes maintenance, and increases overall system reliability.
Difference Between Internal and External Breakers
Unlike external circuit breakers that require additional cabling and housing, internal oil-immersed breakers are directly integrated into the transformer system. This improves efficiency, reduces cost, and ensures coordinated protection with transformer windings.
How to select the right CSP circuit breaker for your transformer？
When selecting the right CSP circuit breaker, provide the following information:
- Transformer oil tank shape: Pole Mounted or Pad Mounted transformer?
- Number of Poles: Single phase 2 poles or three phase 3 pole?
- Transformer capacity(KVA): 5KVA,10KVA,25KVA…..
- Transformer voltage(V): high and low voltage value
- Transformer impedance(%): Short circuit impedance
Typical Applications
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Secondary circuit protection for distribution transformers |
Power network and utility distribution systems |
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Industrial and rural power supply units |
Oil-immersed transformer integrated protection systems |
