Name
Type
Values (Range)
Unit
Description
5=off
Therm-Lev:1
FLOAT32
0.00...9.99
Thermal level of protec-
ted object (1.00 is the
operate level)
4.1.10.10
Technical data
Table 484: MPTTR Technical data
Characteristic
Value
Operation accuracy
Depending on the frequency of the measured
current: f
n
±2 Hz
Current measurement: ±1.5% of the set value
or ±0.002 × I
n
(at currents in the range of
0.01...4.00 × I
n
)
Operate time accuracy
1
±2.0% of the theoretical value or ±0.50 s
4.1.11
Thermal overload protection for rotors RPTTR (ANSI 49R)
4.1.11.1
Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Thermal overload protection for ro-
tors
RPTTR
3Ith>R
49R
4.1.11.2
Function block
Figure 244: Function block
4.1.11.3
Functionality
The thermal overload protection for rotors RPTTR protects the rotor of the
induction motor from overheating. RPTTR models the rotor thermal behavior on the
basis of the measured load current and voltage and disconnects the motor when
the thermal content reaches 100 percent. The rotor thermal overload conditions are
1
Overload current > 1.2 × Operate level temperature
1MRS759142 F
Protection functions
REX640
Technical Manual
423