You are currently not logged in.
Electrical Systems Overview
Purpose
The electrical system provides electrical power to operate all equipment, lighting and instrumentation in the plant. The electrical system includes utility power provided by Chelan County Public Utility District No. 1 and standby power provided by two on-site engine-generators.
Components
The electrical system includes the following components:
  •    Utility Power Service
  •    Utility Transformer
  •    Main Switchboard Panels
  •    Distribution Panel
  •    Motor Control Centers (MCC)
  •    Transformers
  •    Panelboards
  •    Automatic Transfer Switches
  •    Standby Generators
Description

Utility electrical power from Chelan County PUD No. 1 is brought to the site at 2,300 Volts.  The 2,300 volt primary service is stepped down to 480 Volts by a utility-owned 1,000 kVA transformer near the Blower Building.  The incoming power then branches to two destinations: 

   ATS 6E (the automatic transfer switch feeding the UV switchboard)
   SWBD 2 (the switchboard in the Control Building that serves the rest of the plant)

From SWBD 2, power is distributed to SWBD 1 in the Blower Building.  From SWBD 1, power is distributed to Distribution Panel PE also located in the Blower Building. All Motor Control Centers (MCCs), with the exception of the UV Building, are powered by one of these three switchboard distribution centers.
 

The plant electrical one-line diagram graphically portrays the plant's electrical distribution system.

The following MCCs are split into two sections, with one section connected to a backup generator to provide redundant power supply in the event utility power supply is lost:
   MCC 1 / MCC 1E
   MCC 2 / MCC 2E
   MCC 3 / MCC 3E
   MCC 12006 / MCC 12006E

This arrangement provides redundant power to critical loads, and building services as explained below.


Two diesel engine driven, standby generators are located on-site and are automatically started and switched on-line to critical pieces of equipment. A 187 kW standby generator provides 480 V to critical loads in the Control Building, headworks, screenings, and non-potable water.  A 175 kW standby generator provides 480 V to the UV Disinfection Building.

Automatic transfer switches switch between normal and standby generator power automatically when power is lost or of poor quality. 

Utility Power Service Transformer 6
Power from Chelan Co PUD enters the facility underground at the southeast corner of the site.  2,300 V is provided to the site, but is stepped down to 480 volts by a PUD-owned transformer located on the corner of the Blower Building. 

  
ATS - 6E6
  This Automatic Transfer Switch (ATS) supplies power to the UV Building.  One side of the ATS is connected to PUD utility power from the transformer, and the other side of the ATS is connected to a 175 kW backup generator.
SWBD-26
  This switchboard panel is supplied with 480 volts from the connection to PUD's transformer.  The switchboard supplies power to SWBD 1, and to MCC 3, MCC 4, MCC 4A, and MCC 12006.  This switchboard supplies utility power to all loads in the plant except the UV Building. 
SWBD-16
  This switchboard panel is supplied with 480 volts from the connection to SWBD-2 and supplies power to distribution panel PE, and to MCC 1, MCC 2, MCC 5, and the three aeration blowers. This switchboard supplies utility power directly to all loads connected to the Blower Building and to non-critical loads in the Control Building.
Distribution Panel PE6
This panel is supplied with 480 volts from the connection to SWBD-1 and supplies power to the non-potable pumps,and essential loads in the Headworks Building, the Screenings Building, and the Control Building.  This panel is also connected to a 187 kW backup generator through an ATS to supply backup power to essential plant loads.
UV Backup Generator6
  A 175 kW standby generator provides 480 V to the UV Disinfection Building to provide disinfection during utility power outages.
Plant Backup Generator6
A 187 kW standby generator provides 480 V to critical loads in the Control Building, headworks, screenings, and non-potable water.

Back To Top
Last Updated: 9/16/2013 11:49:36 AM
Version 4.0.1