LV Boxes for Pole-Mounted Substations

LV Boxes for Pole-Mounted Substations

The LV box for pole-mounted substation is of light structure, made of 2.5 mm thick aluminum sheet by CNC welding procedure. Upon buyer request, surface is protected by electrostatic procedure using RAL 7035 polyester powder paint, in compliance with the EN norms CEN/TC 271.

The rigidity of the internal prefabricated aluzinc elements is achieved by swaging, without sharp edges or transitions. The bedplate includes slots with screw threads for fast equipment mounting and dismantling. Box doors can be opened on both ends, in the front as well as in the back. The front door can be locked. The back door can be mechanically bolted from the inside of the box.

Roof structure is made to prevent water collection, and at the same time air circulation is enabled within the box. Ingress of insects and rodents into the box is prevented by placement of a PVC protection net. Door overlay and sealing is achieved by the expanding polyurethane mass applied by NC procedure with the protection rating of IP 54. The LV boxes for pole-mounted substations are used for low voltage distribution and are as a standard equipped with 4 LV outgoing lines. Complete electrical equipment of the LV box is dimensioned to the power of the transformer, maximum up to 400 kVA, and network parameters.

Electricity measurement is performed by a digital measurement group or active energy meter through current transformers of the appropriate transmission ratio. If needed, the LV box is equipped with a voltmeter including a voltmeter switch and three ammeters for direct measuring. The supply of the LV box is equipped with a switch which includes an overload release (thermal release) and an overcircuit (electromagnetic) release or a combination of a compact switch and a high performance LV circuit-breaker.

The supply of the LV box is also equipped with surge arresters. The LV outgoing lines are protected by high performance LV circuit-breakers in combination with stands or insulated three-pole withdrawable fuse switch disconnectors. For the needs of service maintenance, the LV box is equipped with a single pole socket with a protective contact and a 60 W power lightbulb with the appropriate switch. Upon buyer request, the LV box is fitted with a fixed reactive power compensation and a public lighting feeder. A one-line diagram, first aid instructions and safety rules (“golden rules”) are placed within the box. High voltage warning plates and substation name plate are placed on the LV box. Labels marking the type of grounding are placed within the box. The LV box for pole-mounted substation possesses all necessary certificates.