City of Naperville; Naperville, IL

Profile:
The City of Naperville is located 28 miles west of downtown Chicago, Illinois. Naperville is home to a number of high technology research centers, corporate headquarters, and facilities for many well-known, national and international companies. One of the fastest growing communities in the United States, Naperville has a population of approximately 136,000 with an ultimate population of 160,000.

The City of Naperville owns and operates an electric utility serving 48,000 residential customers and 3,000 commercial and industrial customers with 800 miles of transmission and distribution lines. The service area includes 46-square-miles of land within the corporate limits. The City purchases all of its electrical needs as wholesale bulk power from Commonwealth Edison Company at 138 kV. The electric utility’s facilities include 12 operational electric substations and 3 electrical substations under construction.

Issue:
Several large commercial customers served by the electric utility have an internal distribution network for their facility extended from the City’s 12.47kV distribution network. These commercial customers are responsible for supporting and maintaining their campus’ medium voltage network. The same feeders provide power to other customers and are protected by the City of Naperville’s substation equipment.

If a cable fault occurs on the commercial customer supported feeder, the City’s ability to restore power is dependent on the facility’s response time. This situation was not acceptable to the Utility vision of providing highly reliable power to its customers. Therefore, the City of Naperville has implemented an application, which allows identification and isolation of the faulty section on the feeder. It made restoration of power to the non-affected part of the feeder minimal, while awaiting diagnostics and maintenance by the commercial customer.

Application:
The application consists of 1) electrical hardware; 2) networking hardware and software; 3) implementation of operation procedure.

1. Horstmann Underground Fault Indicators are installed on the customer side of the self-supported 12.47kV feeder distribution network. The Underground Fault Indicators are equipped with local flashing LEDs and a distribution automation relay, which is designed to provide a pulse or latched contact to a remote terminal unit (RTU) on a SCADA system.

2. The City of Naperville’s SCADA system utilizes conventional substation type RTUs and licensed radio communication. But, for this application, the cost and complexity of such an installation was not justifiable. In lieu of the conventional SCADA RTUs with dedicated radios, the City deployed Telemetric MicroRTUs that utilize the public cellular network. Telemetric MicroRTUs provide an easy way to connect with the Underground Fault Indicators automation relay and do not require a specialized communication infrastructure.

3. The utility Control Room operator is alerted immediately about fault location via the Telemetric Web Server by pager, cell phone, or e-mail. The same notification is sent to the commercial facility manager to initiate the repair.

Benefits:

• Prior to installation of Underground Fault Indicators and deploying Telemetric MicroRTUs, the City of Naperville’s Control Room operators would send a crew to identify the fault location along the feeder after substation breaker operated under fault condition. If the fault was within the commercial property, a phone call to the facility manager had to be placed to initiate the repair.

• The new application provides immediate notification to the Control Room and the customer if the fault is within the commercial facility property.

• Receiving advance notification from the Underground Fault Indicators allows the utility operators to dispatch a power restoration crew within minutes of an outage. This isolates the problem span of the feeder and restores power to customers outside of the facility campus.

• Finally, notification from the Underground Fault Indicators allows a manager at the commercial facility to respond expeditiously to a power outage within the facility, therefore reducing its downtime.