Title :
Integrated metering and protective relay systems-large drive motor applications
Author_Institution :
ASEA Brown Boveri, Allentown, PA, USA
Abstract :
The process of converting sampled analog signals to digital numbers using a low-cost microprocessor and an A/D converter has been found to open unique possibilities for the field of protection. Digital filtering extracts phasor components while suppressing DC offset and unwanted harmonics. These components, used in real-time computations and stored in memory for later communication, make metering, event recording and fault locating an integral part of the protective relay system. Systems employing these techniques provide a range of protection functions in maintainable software that includes self-diagnostics. The systems use unified hardware and provide a significant reduction in the cost per function. These attributes are discussed in terms of the field experience with three microprocessor-based protective relay systems covering distribution, advanced motor protection, and general switchgear applications. Distribution fault records, relay performance with extremely saturated low ratio circuits, and advanced methods of protecting high-inertia drive motors are covered.<>
Keywords :
electric drives; electric motors; microcomputer applications; relay protection; A/D converter; DC offset harmonics; advanced motor protection; digital filtering; distribution fault records; event recording; fault locating; high-inertia drive motors; integrated metering; low-cost microprocessor; protective relay systems; self-diagnostics; switchgear; Analog-digital conversion; Circuit faults; Digital filters; Digital relays; Filtering; Microprocessors; Protection; Protective relaying; Signal processing; Software maintenance;
Conference_Titel :
Industry Applications Society Annual Meeting, 1989., Conference Record of the 1989 IEEE
Conference_Location :
San Diego, CA, USA
DOI :
10.1109/IAS.1989.96855