ABB MICRO-51 Manual

ABB MICRO-51 Manual Manual pdf 1 page image

August, 1991Supersedes Descriptive Bulletin 41-123Mpages 1 and 2, dated January, 1991Mailed to: E, D, C/41-100CMicro-51Micro-511FTFeatures• Eight selectable curves• Wide current tap ranges• Exceptional setting resolution• Self-powered, low burdenABB Power T&D Company Inc.Relay DivisionCoral Springs, FLAllentown, PASingle PhaseDevice Number: 50/51• Transient and EMI immunity• Total-drawout construction• Retrofit existing CO installations• 2 year warrantyDescriptive Bulletin41-123MPage 1CIRCUIT U SHIELD @Types MICRO-51 andMICRO-511FTMicroprocessor-BasedTime-OvercurrentRelaysApplicationMicro-51 microprocessor-based overcurrentrelays are used for phase and ground overcurrent protection in utility, industrial. and commercial electrical power systems. The Micro-51operates from conventional 5A or 1A secondary current transformers. The relay is self-powered from the current; therefore, there is nocontinuous drain on the control voltage supply.Settings are made by front panel switches.Eight time-current curves are built-in, selectable on the front panel:Inverse Long Time InverseVery Inverse Long Time Very InverseExtremely Inverse Long Time ExtremelyDefinite Time InverseShort Time InverseWide current tap ranges with exceptional setting resolution are offered: 1.5-12A in 0.25Aincrements, and 0.3-2.4A in 0.05A increments.The time dial is adjustable from 1 to 10 inincrements of 0.1.An instantaneous element is standard. Instantaneous pickup is adjustable from 1 to 20 multiples of the time-pickup, in increments of 0.1multiples. The instantaneous unit may be disabled by setting the pickup to zero.The Micro-51 can be set for operation on a 50Hz or 60 Hz system by positioning an internallink.The Micro-51 has three electrically isolatednormally-open output contacts: Time trip, Inst.trip, and trip alarm.A led is provided on the front panel to indicatewhen the cc;rrent is above the pickup setting.Two targets are provided for Time and Instantaneous trip indication. Target operation is bytrip circuit current. Reset is manual by a frontpanel magnetic device.The Micro-51 has self-diagnostics that continuously perform functional checks when the inputcurrent to the relay is above a minimum level.The integrity of the ROM, RAM, EEPROM, andanaglog elements are monitored. A red led onthe front panel indicates the detection of aproblem.www . ElectricalPartManuals . com