DHP D265T – Pole-Top Circuit Breaker with Digital Trip Unit
The protection and management of MV/LV transformers in rural areas require specific circuit breakers designed to handle significant load imbalances, thus ensuring full utilization of the installed power even under unbalanced conditions. These products consist of a circuit breaker unit and an analog trip unit.
Description
Circuit Breaker Enclosure
These devices (4 poles, 3 of which are protected) use air interruption and metal-partition arc chambers for arc quenching.
When the breaker is open, a contact establishes an electrical connection between the transformer’s neutral and the system ground. When the breaker is closed, a spark gap limits the potential rise of the LV neutral relative to ground to a value above 10 kV.
The breaker is housed in a weather-resistant polyester enclosure reinforced with fiberglass.
Digital Trip Units
The Digital Trip Unit ensures protection for three transformer ratings on pole-mounted installations (50 kVA or 100 kVA for this model), whether conventional transformers (without internal protection) or new transformers with integrated protection (TPC).
A selector switch allows the user to set the appropriate transformer protection rating. The microcontroller continuously estimates the transformer’s probable temperature based on the three-phase currents and the ambient external temperature. The latter is calculated from the sensor and a mathematical model, which also takes the three phase currents into account.
If a Digital Trip Unit is integrated into an older generation pole-mounted circuit breaker, the load integrator function—if present—will be disabled.
Features
Operating Rod System