Megawin switchgear provides numerical over-current / earth fault relay. The type ms 61c [lbs/bp] is a unique relay that receives current input signals from current sensors. Innovative construct of numerical over-current / earth fault relay ensures that relay settings can be done directly in terms of primary current, thus avoiding complex ct ratio calculations. The value of fault current at the time of relay tripping is displayed in the backlit lcd display, till the relay is reset. The current and time settings are set using membrane keypads in a 2 line, 16-character backlit lcd display. The numerical over-current / earth fault relay offers 6 types of standard idmt curves, a long time delay curve and also a definite time feature for both the o/c as well as the e/f relays. For use in circuit breaker feeder, a high set relay feature can be given for both o/c and e/f relays, which can be enabled or disabled. The entire relay settings are secured with password protection. If the relay is used for a load break switch feeder, then the numerical over-current / earth fault relay gives only low-set idmt protection for both o/c and e/f relays. Leds are available for pick-up, low-set fault [o/c and e/f], high set fault [o/c and e/f], r/y/b phases and earth fault. Thus diagnosis becomes easier, during the relay pick-up as well as post trip conditions. The fully microprocessor-based relay has two sets of output change over contacts each for the o/c and e/f relay. The over current settings are available from 5 to 200 a and earth fault settings from 1 to 80 a. Tms settings are available from 0.1 to 1.6. The high set o/c settings exist from 20 to 2000 a and the high set e/f settings are from 5 to 800 a. The accuracy is ±5% on idmt and ±3% on definite time. Over all dimensions of the numerical over-current / earth fault relay are very compact at 155 [w] x 216 [d] x 177 mm [h].
