The construction of a major Power Station or Tunnel system requires significant amounts of “temporary” power, to supply accommodation villages, offices for hundreds of site based engineers, welfare facilities for site operatives, complex on-site IT and communication systems, as well as concrete batching plants, tower cranes, hoists and heavy duty electrical plant. On major projects equipment can be required to work 24/7 for periods of 5 to 10 years, which means that there is no opportunity to isolate main switchboards to facilitate safe connection or disconnection of circuits. To address the need to be able to connect and disconnect circuits as a matter of routine and with the minimum of disruption, we have designed a modular range of Mains Distribution Assemblies (MDAs) with Form 4 segregation, which enable any circuit to be connected or disconnected without interfering with the other circuits.
MDAs with Form 4 segregation are generally limited to primary distribution assemblies, typically rated from 800A to 3200A. Incoming MCCBs or ACBs (and high current outgoing devices over 800A rating) are housed in compartments that require access to the front and rear. Lower current outgoing devices rated up to 800A are mounted in separate compartments fitted to both sides of the enclosure (back to back).
The lower current distribution sections are constructed in 1700mm long modules with the facility for 3 x 800A frame MCCBs, 4 x 630A frame MCCBs or 5 x 250A frame MCCBs per side (all 4P, with or without RCD). The modular construction enables a wide combination of distribution switchgear to be fitted utilising standard enclosure components, which reduces lead time and eliminates the cost of designing bespoke metalwork.
Form 4 MDAs are designed to incorporate smart metering, incoming changeover arrangements, RCD protection, test sockets, anti-condensation heaters, power factor correction, bus couplers, surge protection devices, sun canopies, etc.
If you would like to discuss a Form 4 MDA for a major project, please contact our Projects Team who would be pleased to assist.
Download pdf here