ACS 400 User’s Manual25Q Motor Overload ProtectionIf the motor current I out exceeds nominal current IN of the motor for a prolonged period, theACS 400 automatically protects the motor against overheating by tripping.The trip time depends on the extent of the overload (Iout / IN), the output frequency and f nom . Timesgiven apply to a “cold start”.ACS 400 provides overload protection in accordance with the National Electric Code (US). Defaultsetting is motor thermal protection ON. For more information see Group 30 parameters, page 85 inthis manual.Figure 31R Loadability of ACS 400In the event of an output overload, the ACS 400 will first show an alarm and then trip.Figure 32Iout / INOutput frequency1.51.00.500 35 Hzduty cycle = t/TT < 10 minAmbient temperature,θamb max. is 40°C.50°C is permissible,if I2 and I max are derated to 90 %.Iout t ImaxI2T timeImax / I2Duty cycle1,51.41.31.21.11.00.1 0.2 0.3 0.4 0.5Constant torque ratingSquared torque ratingImax = maximum output currentin squared torque (I2NSQmax) andconstant torque (I2Nmax)applications, see Table 11.
