To adjust the actuation current in the relay, it is common practice to multiply the Motor Service Factor (FS) by its nominal current, both values found on the nameplate of the motor to be protected. Some literature recommends multiplying the FS by the rated current measured during engine operation.
Example: In a three-phase induction electric motor, IP55, insulation class B, power 3.7Kw (5.0 HP-hp), Un 220 / 380V, In. 13.1 / 7.58 A, FS 1.15 , Ip / In 8.0, the relay set current should be:
IAJUSTE = F.S. x In
For delta motor connection:
YAJUST = F.S. x In (triangle)
YIELD = 1.15 x 13.1
IAJUST = 15.065 A
For starter motor connection:
YAJUST = F.S. x In (Y)
YIELD = 1.15 x 7.58
YIJUST = 8.717 A
