CHAPTER 3: MOTOR PR OTECTION
EP OS MOTOR MANAGEMENT SY STEM – INSTRUCTION MANUAL
3.3
3.1.3 Overload curve
The overload curve accounts for the rapid motor heating that occurs during stall, acceleration, and overload.
Specifically, the overload curve controls the rate of increase of the accumulated motor heating value
whenever the equivalent average motor heating current is greater than 1.12 times the full-load current
setpoint .
EntelliPro ES supports eight overload curves, class 5, 10, 15, 20, 25, 30, 35, and 40, that are in compliance with
IEC 60947-4-1. Each class corresponds to a maximum trip time allowed when the applied primary current is
7.2 times the EntelliPro ES IN setting. The trip-time accuracy is
±10% for up to 8 times
the motor load
and ±20%
The overload curve can be set in the WinESG parameterization/device settings panel shown in the illustration
below, or Modbus function code 6 register 12.
Figures 3-1 and 3-2, and Tables 3-1 and 3-2 show the trip-time curves for classes 5, 10,
1
5, 20, 25, 30, 35, and
40 under normal and phase loss conditions.
NOTE:
If a phase unbalance and/or phase loss is recognized, the EntelliPro ES speeds up the thermal model.
The primary average current is multiplied by 1.43 its original value in a phase-unbalance state and by 1.85 its
original value in a phase-loss state.
from 8 to 10 times the motor load.
