tMax: For overvoltages close to the set value times can be extremely long if a highK time constant is used. A maximum time can then be set to cut the longest times.Typical settings are 1800-3600 seconds (30-60 minutes)AlarmLevel: Setting of the alarm level in percentage of the set trip level. The alarmlevel is normally set at around 98% of the trip level.tAlarm: Setting of the time to alarm is given from when the alarm level has beenreached. Typical setting is 5 seconds.10.4.3.3 Service value report M6496-144 v4A number of internal parameters are available as service values for use atcommissioning and during service. Remaining time to trip (in seconds)TMTOTRIP, flux density VPERHZ, internal thermal content in percentage of tripvalue THERMSTA. The values are available at local HMI, Substation SAsystemand PCM600.10.4.3.4 Setting example M6496-108 v5Sufficient information about the overexcitation capability of the protected object(s)must be available when making the settings. The most complete information isgiven in an overexcitation capability diagram as shown in figure 290.The settings V/Hz>> and V/Hz> are made in per unit of the rated voltage of thetransformer winding at rated frequency.Set the transformer adapted curve for a transformer with overexcitationcharacteristics in according to figure 290.V/Hz> for the protection is set equal to the permissible continuous overexcitationaccording to figure 290 = 105%. When the overexcitation is equal to V/Hz>,tripping is obtained after a time equal to the setting of t1.This is the case when UBase is equal to the transformer ratedvoltages. For other values, the percentage settings need to beadjusted accordingly.When the overexcitation is equal to the set value of V/Hz>>, tripping is obtainedafter a time equal to the setting of t6. A suitable setting would be V/Hz>> = 140%and t6 = 4 s.The interval between V/Hz>> and V/Hz> is automatically divided up in five equalsteps, and the time delays t2 to t5 will be allocated to these values ofoverexcitation. In this example, each step will be (140-105) /5 = 7%. The setting oftime delays t1 to t6 are listed in table 42.Section 10 1MRK 506 369-UEN BVoltage protection550 Line distance protection REL670 2.2 IECApplication manual
