The calibration factors for current and voltage measurement errors are set % of rated current/voltage:IMagComp5, IMagComp30, IMagComp100VMagComp5, VMagComp30, VMagComp100IMagComp5, IMagComp30, IMagComp100The angle compensation is given as difference between current and voltage angle errors.The values are given for operating points 5, 30 and 100% of rated current/voltage. The valuesshould be available from instrument transformer test protocols.8.7 Directional overpower protection GOPPDOP (32) SEMOD172360-1 v48.7.1 IdentificationSEMOD176574-2 v4Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberDirectional overpower protection GOPPDOPP >2DOCUMENT172362-IMG158942V2 EN-US328.7.2 Application SEMOD172358-4 v2The task of a generator in a power plant is to convert mechanical energy available as a torque on arotating shaft to electric energy.Sometimes, the mechanical power from a prime mover may decrease so much that it does notcover bearing losses and ventilation losses. Then, the synchronous generator becomes asynchronous motor and starts to take electric power from the rest of the power system. Thisoperating state, where individual synchronous machines operate as motors, implies no risk for themachine itself. If the generator under consideration is very large and if it consumes lots of electricpower, it may be desirable to disconnect it to ease the task for the rest of the power system.Often, the motoring condition may imply that the turbine is in a very dangerous state. The task ofthe reverse power protection is to protect the turbine and not to protect the generator itself.Steam turbines easily become overheated if the steam flow becomes too low or if the steamceases to flow through the turbine. Therefore, turbo-generators should have reverse powerprotection. There are several contingencies that may cause reverse power: break of a main steampipe, damage to one or more blades in the steam turbine or inadvertent closing of the main stopvalves. In the last case, it is highly desirable to have a reliable reverse power protection. It mayprevent damage to an otherwise undamaged plant.During the routine shutdown of many thermal power units, the reverse power protection gives thetripping impulse to the generator breaker (the unit breaker). By doing so, one prevents thedisconnection of the unit before the mechanical power has become zero. Earlier disconnection1MRK 511 364-UUS A Section 8Current protection143Application manual
