Siemens SINAMICS S120 System Manual page 160

Configuring
11.1 Features
In the event of a power failure and simultaneous energy recovery of a synchronous motor, the
DC link voltage may increase excessively. In this case, a Braking Module with connected braking
resistor helps to limit the DC link voltage. A Control Supply Module is required for this. This
detects a power failure on the primary side, converts its supply voltage from 3-phase supply
system to supply from the DC link voltage, and therefore continues to make 24 V available for the
Braking Module.
Calculating the maximum speed for synchronous and induction motors
Table 11-2 Overview of parameters to calculate the speed
Parameter Meaning
r0297 Overvoltage threshold DC link 820 V
p0233 Filter inductance, 0.036 mH
p0234 Filter capacitance [µF]
16 kHz
32 kHz
p0304 Rated motor voltage [V]
p0310 Rated motor frequency [Hz]
p0311 Rated motor speed [rpm]
p0314 Motor pole pair number
Synchronous motor:
Induction motor:
p0315 Motor pole pair width [mm]
p0316 Motor torque constant, rotary [Nm/A]
Motor force constant, linear [N/A]
p0317 Motor voltage constant [V]
p0348 Speed at the start of field weakening [rpm] for V
p0353 Motor series inductance [mH]
p0356 Motor stator leakage inductance [mH]
p0358 Motor rotor leakage inductance [mH]
p0360 Motor magnetizing inductance [mH]
Motor leakage inductance / armature inductance (incl. series inductance, if applicable)
Synchronous motor:
Induction motor:
The pole pair number for induction motors corresponds to the numbers in front of the decimal place of the calculated
1)
parameter.
The maximum motor speed for synchronous and induction motors can be calculated with the
following formulas. Here, the parameters should be used in the units listed in the tables above.
158
Without additional capacitance
11.9 µF
2.72 µF
On the rating plate
p0314 = (p0310 [Hz] • 60) / p0311 [rpm]
= 600 V (425 V
dc
L_motor [mH] = p0356 + p0353
L_motor [mH] = p0356 + p0360 - p0360
With additional capacitance
15.2 µF
3.4 µF
1)
/ p0317 · 1000 rpm)
rms
/ (p0360 + p0358) + p0353
2
High Frequency Drive
System Manual, 10/2020, 6SL3097-5AH10-0BP0