IEEE Std 1527:2006 pdf free download

IEEE Std 1527:2006 pdf free download.IEEE Recommended Practice for the Design of Flexible Buswork Located in Seismically Active Areas.
5. Other connection possibilities
Due to the reduced height of the buswork, the greater inherent stiffness and relatively smaller mass of the components, most equipment a the 12 kV, 25 kV. and 69 kV voltage levels is able to withstand greater seismic forces and will he subject to far less differential movement. While rigid buswork design is generally acceptable. areas of concern are connections to major equipment bushings. Transformer, circuit breaker and voltage regulator bushings. in addition to being vulnerable, will require considerable lead times to replace should damage occur and therefore, must be subject to a high level of protection if service is to be readily restored subsequent to a seismic event.
The flexible buswork from rigid buswork to equipment bushings is ideally accomplished by using stranded bare conductor, braided conductor, or expansion terminal connectors. The latter two will limit flexibility sufficiently to avoid compromising the phase-to-phase clearances under short-circuit loading and the voltage gradient across the insulators, particularly for 12 kV and 25 kV equipment.
6. High-current connections
For the purpose of this document, high-current flexible buswork connections are defined as those being capable of carrying 3000 A or more, and should utilize the conductor configurations discussed in Clause II. They can have either bolted or welded connection joints and normally utilize two or more bare stranded con ductors or plates connected in parallel. These conductors or plates can be either copper or aluminum. although aluminum is more widely used. As with the lower current flexible buswork connection, the basic design factors must be considered and satisfied. However, unlike the lower current flexible buswork connection designs. stricter attention must be paid to the connection method, the current density capacity. the contact surface area, the surface preparation. and the contact pressure or “clamping” to ensure that the high-current flexible buswork connection functions properly in-service.
For connections with current-carrying capacities of up to and including 5000 A. bolted joints can be used as part of the flexible buswork connection provided that they are properly designed and installed.