What is a LV Pole mounted circuit breaker

LV pole mounted circuit breakers are mainly used for the protection and management of MV/LV transformers in rural areas. They are designed to adapt to significant load imbalances, ensuring the full utilization of installed power even under unbalanced conditions.

DT165T-DT265T LV Pole mounted circuit breakers

### Structure and Working Principle
– **Pole Structure**: These circuit breakers are usually tetrapolar, with three – phases protected and one neutral.
– **Arc – Extinguishing Technology**: They adopt air – break technology. Metal partitions are used in the chambers to divide the arc, which helps to extinguish the arc effectively and improve the breaking performance of the circuit breaker.

### Characteristics and Advantages
– **Transformer Protection**: They can protect pole – mounted transformers of 50 kVA, 100 kVA, or 160 kVA. They work with both conventional transformers without internal protection and new transformers with MV fuses (TPC). Users only need to set the correct rate from a selector according to the transformer’s power.
– **Neutral Potential Protection**: When the circuit breaker is closed, a spark gap limits the rise in potential of the LV neutral from the earth, preventing it from exceeding 10 kV. When the circuit breaker is open, an electrical connection is made between the neutral of the transformer and the ground, ensuring the safety of the transformer and the power grid.
– **Compact and Easy to Use**: They are more compact and easier to use than fused solutions, which simplifies the installation and operation process and reduces the space occupied by equipment.

### Technical Parameters
– **Rated Voltage**: Usually 440 V.
– **Rated Current**: Such as 165 A and 265 A.
– **Rated Short – Circuit Breaking Capacity** and **Rated Short – Circuit Making Current**: For example, 4000 A and 6800 A for D165T, 6400 A and 11700 A for D265T.
– **Insulation Level**: The rated power – frequency withstand voltage (50 Hz – 1 min) is 4 kV for phase – to – phase and phase – to – earth, and the rated lightning impulse withstand voltage (1.2 / 50 μs) is 20 kV.

In conclusion, LV pole mounted circuit breakers play a crucial role in the low – voltage power distribution system, especially in rural areas. They provide reliable protection and management for transformers, ensuring the safe and stable operation of the power grid.