57.4mm Mounting Hole Single Phase Circuit Breakers, Used For Single Phase Oil Immersed Distribution Transformers.CSP Circuit breaker Is Installed On The Secondary Winding Of The Transformer, Is Used For Over Load Protection And Short Circuit Protection.
| Model | 3P157T110 |
| Rated Current | 157A |
| For Transformer | 100KVA/112.5KVA |
| Rated Voltage | 400V/420V |
| Trip Temp. | 110℃, 120℃, 130℃ |
| Phase | 3F |
| Mounting Hole Diameter | 57.4mm |
lt is three phase circuit breakers, used for three phase transformers. Circuit breaker are installed onthe secondary winding of the transformer, are used for over load protection and short circuit protection.
| Model | Current (A) | Rating (KVA) | Voltage (V) | Signal light | Emergency switch (overload) | Magnetic protection | Resistance (Ω) at 25°C 2 poles | Loss (W) at 85°C 2 poles |
|---|---|---|---|---|---|---|---|---|
| 3P63TXXX | 63 | 45 | 400 | Yes | Yes | No | 3150 | 15.2 |
| 50 | 420 | |||||||
| 3P105TXXX | 105 | 75 | 400 | Yes | Yes | No | 1350 | 18 |
| 75 | 420 | |||||||
| 3P157TXXX | 157 | 100 | 400 | Yes | Yes | Yes | 1200 | 36 |
| 112.5 | 420 | |||||||
| 3P210TXXX | 210 | 150 | 400 | Yes | Yes | Yes | 1140 | 63 |
| 150 | 420 | |||||||
| 3P313TXXX | 313 | 200 | 400 | Yes | Yes | Yes | 750 | 90 |
| 225 | 420 | |||||||
| 3P420TXXX | 420 | 300 | 400 | Yes | Yes | Yes | 680 | 148 |
| 300 | 420 | |||||||
| 3P433TXXX | 433 | 300 | 400 | Yes | Yes | Yes | 680 | 157 |
| 300 | 420 |
| Max Voltage | Power Frequency Test (one minute) 50/60HZ | Lightening Impulse Test | Insulation Resistance (5000V) | Normal Interrupting Capacity |
|---|---|---|---|---|
| 600V | ≥10KV | 30KV | ≥5000MΩ | 11KA~20KA |
| Model | Current (A) | Interrupting Capacity(KA) |
|---|---|---|
| 3P42TXXX | 42 | 4 |
| 3P63TXXX | 63 | 4 |
| 3P105TXXX | 105 | 7 |
| 3P157TXXX | 157 | 11 |
| 3P210TXXX | 210 | 11 |
| 3P313TXXX | 313 | 20 |
| 3P420TXXX | 420 | 20 |
(Trip temperature = Bi-metal trip temperature)
| No. | Bimetal ID | Current (I: A) | Bi-metal Ampere Response Factor (J: °C/A²) | Bi-metal temperature rise to oil (ΔT: °C) | Oil temperature (To: °C) | Bi-metal temperature (T: °C) |
|---|---|---|---|---|---|---|
| 01 | 21 | 21 | 0.0125000 | 5.5 | To | 5.5+To |
| 02 | 42 | 42 | 0.0040000 | 7.1 | To | 7.1+To |
| 03 | 63 | 63 | 0.0019904 | 7.9 | To | 7.9+To |
| 04 | 105 | 105 | 0.0008114 | 9.5 | To | 9.5+To |
| 05 | 157 | 157 | 0.0002000 | 4.9 | To | 4.9+To |
| 06 | 210 | 210 | 0.0001120 | 4.9 | To | 4.9+To |
| 07 | 313 | 313 | 0.0000610 | 6.0 | To | 6.0+To |
| 08 | 420 | 420 | 0.0000720 | 12.5 | To | 12.5+To |
| 09 | 433 | 433 | 0.0000720 | 13.5 | To | 13.5+To |
T:Bi-metal temperature(℃ )
ΔT:Bi-metal temperature rise to oil(℃ )
To:oil temperature(℃)
I:Current flow through the Bi-metal trip in(A)
J:Bi-metal Ampere Response Factor in (J:℃ /A²)
ΔT=I²*J
T= ΔT+To
Note: When Bi-metal temperature reaches the trip temperature setting of the breaker,the breaker trip.
The following drawings show only partial product dimensions.
For the complete set of engineering drawings or full specifications, please contact us at [📪nancywang@ketranele.com].

Thank you for using our CSp type circuit breakers, when you receive circuit breakers, please be informed with the following tips:
❶ If you need put the circuit breakers into dry oven for drying process, please make sure remove the lamp cover; lampbulb and lamp sealing ring before put into dry oven.
❷ After long-time drying process, it maybe make a few circuit breakers dificult to operate on opening and closing, youcan just put some transformer oil on the circuit breakers,it will work smoothly again.


Q1: What is a three-phase CSP oil-immersed circuit breaker?
A1: Three-phase CSP oil-immersed circuit breaker is a high-voltage distribution device with Completely Self Protected (CSP) functionality. Widely used in pole-mounted three-phase transformers , pedestal-mounted or pad-mounted box-type three-phase transformers .
Q2: What is the difference between a three-phase CSP oil-immersed circuit breaker and a single-phase circuit breaker?
A2: The main difference lies in the number of phases and application scenarios. A three-phase circuit breaker can control all three phases simultaneously, suitable for industrial power systems and high-power equipment, while a single-phase breaker is mainly used for small-scale distribution or rural grid branches. Three-phase CSP breakers offer better synchronization and current balancing.
Q3: What application scenarios are CSP circuit breakers suitable for?
A3:CSP circuit breakers are widely used for distribution transformer protection, rural grid upgrades, industrial and mining power supply systems, and wind or solar power grid integration. Their high reliability and automatic protection features make them ideal for unmanned or complex environments.
Q4: Can the product be customized according to customer needs?
A4: Yes. Customization is available based on customer requirements for rated voltage, current, installation type, and control scheme, including OEM services.