Detail Frequency And Voltage Protection – Argus 8 – 7SG11
Voltage and frequency protection The ARGUS 8 series of voltage and frequency relays are numerical, multi-function devices that are designed to be applied for the protection of transmission, distribution and industrial systems. ARGUS 8 can be used for load shedding and other protection purposes, and can provide phase under and over voltage, neutral displacement overvoltage, negative sequence overvoltage and under and overfrequency protection elements. ARGUS 8 is part of the comprehensive range of ARGUS-platform based numeric relays. These relays have extensive control functions, which are supplemented by advanced metering, data storage and fibre-optic communications. Supervisory and self monitoring features give added confidence to the user as well as reduced maintenance and down time. A menu-based interface gives user-friendly access to relay settings, meters and operational data. FEATURES • Each phase voltage element can be configured for undervoltage or overvoltage • With 2 or 3 phase measurement each element can be configured to require operation of any phase or all phases. • Negative sequence overvoltage with two elements • Neutral voltage displacement with two elements • Four independent frequency elements, each of which can be configured for underfrequency or overfrequency • Frequency elements can be blocked by voltage elements, enabling simple logic schemes • Independent definite time delays for each element • Modbus IEC 60870-5-103 protocol for communicating • Fibre optic or RS485 electrical communication • Fault, event & waveform recorder • Starter & trip LED Indication DESCRIPTION The protection functions available in ARGUS 8 have many possible applications, some of which are mentioned within the descriptions below. Undervoltage and overvoltage Four independent elements are supplied, each of which can be set to operate for undervoltage or overvoltage conditions and all having separate definite time delay elements. These can be used to protect generators against overvoltages, motors against loss of supply or applied as backup protection in the event of defective system regulating equipment. Negative sequence overvoltage Two independent elements are supplied, each of which has a definite time delay element. These can be used to monitor the quality of the supply and protect plant or feeders against system unbalance. Neutral voltage displacement Two independent elements are supplied, each of which has a definite time delay element. These can be used to detect earth faults in high impedance earthed or isolated systems. For this feature, the residual voltage can be measured directly from an open delta tertiary winding or calculated internally from the three phase voltage inputs. These elements include a third harmonic filter, which de-sensitises the elements to any superimposed third harmonic frequencies. Underfrequency and overfrequency ARGUS 8 – 200/ 300 series only. Four independent elements are supplied, each of which can be set to operate for underfrequency or overfrequency and all having separate definite time delay elements. These can be applied wherever frequency protection is required to maintain system stability e.g. in load shedding schemes. The accuracy and security of operation of the numeric algorithms enables the relay to be employed to detect any frequency abnormalities. SYSTEM DATA ARGUS 8 variants with two voltage inputs have a ' 2 Systems A/ B‘ connection setting. This allows two different systems each to be assigned two of the under/ overvoltage elements, using one of the voltage inputs for each system. This feature could be used as part of a local generation scheme with islanding capability, where one input is allocated to the local system, and the other to the grid.