Lenze i950 Series, Manual

Page: 290 / 500

13.9.1.1 Parameters for the thermal model
The introduction of a two-component model with two time constants (one for the winding
and the other for the housing/laminated core) serves to display the thermal behaviour of the
motors up to 500% of the rated current.
Structure of the monitoring
2
(1 + p )
τ
2
1
k
2
(1 + p )
τ
1
1
k
1
I
act Motor
I (n)
perm Motor
①
Thermal utilisation of the motor in [%]
Parameter Symbol Description Dimension unit
- I
actMotor
Actual motor current A
- I
permMotor
Permissible motor current (speed-
dependent) A
0x2D4C:001 τ
1
Therm. time constant of winding s
0x2D4C:002 τ
2
Therm. time constant of laminated
core s
0x2D4C:003 k
1
Percentage of the winding in the
final temperature %
- k
2
Percentage of the laminated core in
the final temperature: k2 = 100 % -
k1 %
Calculation with only one time constant
If k1 = "0 %" is set, the part of the winding is not taken into consideration and the thermal
model is only calculated using the time constant set for the housing/laminated core. This set-
ting is e.g. required if only the time constant of the laminated core (T2) is known.
Parameter setting of the time constant and the influence of the winding on motors of other manufacturers
When the influence of the winding is activated, the i
2
xt monitoring becomes more sensible as
if only the influence of the laminated core would be used for monitoring purposes.
The necessity to activate the influence of the winding rises with the increasing utilisation of
the motor overload capacity. It also rises with applications where the motor is at standstill for
longer periods or cyclically and a load ≥ permanent standstill current is applied.
For determining the values for the thermal time constant, try to get the data from the motor
manufacturer. If this is not possible, you can use the data of a comparable Lenze motor.
Conditions for comparability are similar values in case of the following motor features:
•
Square dimensions of the motor (active part)
•
Length of the active part (if available)
•
Permanent standstill current Io [A_RMS]
•
Peak current/overload capacity [A_RMS]
•
Copper resistance of the winding at 20 °C [Rphase]
Example:
Motor features Data of the third-party motor Description
Square dimension 95 mm MCS09xxx = 89 mm
Standstill current 2.2 A MCS09F38 = 3.0 A
Peak current 7.3 A MCS09F38 = 15 A
Phase resistance 5.1 Ohms MCS09F38 = 5.2 Ohms
Configuring the motor control
Motor protection
Motor overload monitoring (i²*t)
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