ABB RELION REX640 Technical Manual page 428

Protection functions
The ambient temperature TEMP_AMB is available in the monitored data view.
The
• If the ambient temperature measurement value is not connected to the
AMB_TEMP input in ACT.
• When the ambient temperature measurement connected to RPTTR is set to "Not
in use" in the RTD function.
• In case of any errors or malfunctioning in the RTD input.
Max current selector
Max current selector selects the highest measured True RMS phase current and
reports it to Thermal level calculator.
Rotor resistance calculator
The module calculates rotor resistances as a function of estimated slip. Slip
estimate is based on the measured phase currents and line voltages.
Necessary initial values for slip estimation are rotor resistance at locked rotor and
rotor resistance at nominal speed, calculated with following equations. Settings
mentioned in equations can be found from the motor datasheet information.
R
N
RPM
RPM
=
R
L
T
L
I
L
In addition to R
currents to calculate the apparent total resistance and the initial stator resistance.
=
S
R
Table continues on the next page
428
Env temperature Set setting is used:
= 1 −
is the rotor resistance at nominal speed,
is the setting Nominal speed and
N
Synchronous speed.
is the setting
S
2
is the rotor resistance at locked rotor,
Relative starting torque and
is the setting
is the setting Relative starting current .
and R , the slip estimate calculation uses line voltages and phase
N L
1.2∙ ( ) − ( )
is the motor slip,
is the apparent total resistance calculated from line voltages and
phase currents,
1MRS759142 F
(Equation 48)
(Equation 49)
(Equation 50)
REX640
Technical Manual