Eastwater Plants 1 & 2 HSPS Switchgear Improvements

Project Scope

The High Service Pump Station 1 at the Eastwater Purification Plant consist of 7 pumps/motors at 4,160volt totaling 12,500 horsepower. The project parameters were to build a new North Electrical Building to house the majority of new Eaton 4,160volt Arc Resistant Switchgear around the existing antiquated Intertie Switchgear Building so all of the Water Production Facilities would not be interrupted while switching over from old to new. The construction sequence was critical as it dictated the order in which all items would occur facilitating water production at all times. This included the extensive multi-layered underground ductbank systems, drilled slurry foundations, structural steel building frame, masonry building wall construction, electrical switchgear deliveries and placement along with conduit and wiring system all of which had to be in place, tested and operational before a single load could be transferred from the old system to the new. The new Arc Resistant Switchgear at Plant 1 were fed by twin 3000amp, 4.16Kv feeders (six 750Kcmil per phase) from the existing 138Kv Substation Switchgear at Plant 3. They included Multilin L90 differential relay protection over fiber since the two locations were 4500 feet apart. This work required close coordination with CenterPoint as the two 138Kv Substation Transformers had to be turned off one at a time to allow secondary CT replacement. All loads were shifted by use of the Main-Tie-Main in the lineup to accomplish these task. Also, an electronic breaker control system was added to the Plant 3 Substation that allowed the Electrical Operations Group to operate the breakers from a safe remote location with an HMI that showed breaker status. In addition to the medium voltage systems, all SCADA control systems had to be commissioned and on line running parallel with the existing systems before the first loads were transferred from old to new.