ABB 615 series Technical Manual page 305

1MAC059074-MB A
615 series ANSI
Technical Manual
GUID-1E5F2337-DA4E-4F5B-8BEB-27353A6734DC-ANSI V2 EN
Figure 142: Functional module diagram
Max current selector
Max current selector selects the highest measured TRMS phase current and reports it to
Thermal level calculator.
Internal FLC calculator
Full load current (FLC) of the motor is defined by the manufacturer at an ambient
temperature of 40°C. Special considerations are required with an application where the
ambient temperature of a motor exceeds or remains below 40°C. A motor operating at a
higher temperature, even if at or below rated load, can subject the motor windings to
excessive temperature similar to that resulting from overload operation at normal ambient
temperature. The motor rating has to be appropriately reduced for operation in such high
ambient temperatures. Similarly, when the ambient temperature is considerably lower
than the nominal 40°C, the motor can be slightly overloaded. For calculating thermal level
it is better that the FLC values are scaled for different temperatures. The scaled currents
are known as internal FLC. An internal FLC is calculated based on the ambient
temperature shown in the table. The Env temperature mode setting defines whether the
thermal level calculations are based on FLC or internal FLC.
When the value of the Env temperature mode setting is set to the "FLC Only" mode, no
internal FLC is calculated. Instead, the FLC given in the data sheet of the manufacturer is
used. When the value of the Env temperature mode setting is set to "Set Amb Temp" mode,
the internal FLC is calculated based on the ambient temperature taken as an input through
the Env temperature Set setting. When the Env temperature mode setting is on "Use input"
mode, the internal FLC is calculated from temperature data available through resistance
temperature detectors (RTDs) using the AMB_TEMP input.
Section 4
Protection functions
299