Lv Line And Transformer Protection Pole Mounted Circuit Breakers
LV Pole Mounted breaker / digital trip unit
The protection and management of MV/LV transformers in a rural environment requires specific circuit breakers compatible with significant load differences, thus ensuring full exploitation of the installed power, even in unbalanced operation.
Technical characteristics
Standards
Stadards: HN 63-S-11
Electrical Values
Rated Voltage(Ur): 0.44KV
Rated Current: 165A
Rated short-circuit breaking capacity: 4KA
Rated short-circuit making current: 6.8KA
Rated short-time withstand current(1s): 4KA/S
Rated power-frequency withstand voltage(50HZ-1 min): 10KV
Lighting impulse withstand level of ovtage(1.2/50): 20KV
Features
Degree of protection: IP31
Number of outputs: 1
Conductor size: 25-70mm²
Temperatures
Operating temperature: -25...50°C
Storage temperature: -25...70°C
Description Circuit breaker unit These units (4 poles 3 of which are protected) cut off in air with metal partition chambers to break the arc. When the circuit breaker is open, a contact makes an electrical link between the transformer neutral and the station structural earth. When the circuit breaker is closed, a spark gap limits the rise in potential of the LV neutral, in relation to the structural earthing, for a value exceeding 10 kV. The circuit breaker is installed inside a weatherproof GRP case. Digital Trip Unit The Digital Trip Unit protects the three ratings of the post-mounted transformer (50 kVA, 100 kVA and 160 kVA), whether it be a conventional transformer (no internal protection) or a new transformer with protection (TPC). The transformer protection rating is set by a selector. The micro-controller assesses the transformer temperature in real time, based on the currents in the three phases and the external ambient temperature. This ambient temperature is computed based on the probe and a mathematical model that is also a function of the three phase currents
