Be a Server or a Client
Reprinted from December 1995 issue of ELECTRICAL WORLD. Copyright 1995, McGraw-Hill, Inc. All rights reserved.
Requirements
Energy usage at Stone Container Corp, Uncasville, Conn, is monitored by polling 41 smart meters and relays in remote equipment rooms and then communicating over an RS485 twisted pair to a host computer. The system, known as ACCESS, is supplied by Siemens Energy & Automation Inc. The data, graphically displayed, enable Stone Container facilities engineers to picture, in real time, the complete pattern of power usage throughout the mill.
Solution
The smart meter concept is evident on the 12-section lineup of 15-kV switchgear. Each circuit breaker is interfaced with a Siemens Model 4700 power meter, which replaces up to 20 analog instruments and provides measurements of overy parameter of power usage.
Benefit
A key feature of the ACCESS system is that it's software runs on Microsoft Windows, which incorporates Dynamic Data Exchange (DDE). Any instrument that has DDE capabilities can feed into the ACCESS system as a server. Alternatively, ACCESS instruments could feed into any client software system running under Windows. For example, the 15 Siemens 2400-V medium voltage controllers at Stone Container incorporate microprocessor-based motor management relays that can communicate with the ACCESS system. The relays record how many times a motor has tripped and sense motor overheating.
Power-quality parameters can be served to the ACCESS system by a power meter. Siemens offers a range of ACCESS compatible meters designed for a wide variety of applications.
In a $26-million modernization project at Stone Container, Siemens supplied switchgear, motor control centers, programmable logic controllers (PLCs), and the ACCESS electrical distribution and control system. PLCs are good data converters - for instance, from Square D's Modbus to Siemens Cbus or from any serial data protocol to analog and contact data.