Siemens CU240B-2 Operating Instructions

6.34 Kinetic buffering (Vdc min control)
Kinetic buffering increases the drive availability. The kinetic buffering utilizes the kinetic energy
of the load to buffer line dips and failures. During a line dip, the inverter keeps the motor in the
switched-on state for as long as possible. One second is a typical, maximum buffer time.
Preconditions
The following prerequisites must be fulfilled to practically use the "kinetic buffering" function:
● The driven load has a sufficiently high inertia.
● The application allows a motor to be braked during a power failure.
The Vdc_min control is possible only with the PM240‑2, PM240P‑2 and PM330 Power Modules.
Function
When the line supply dips or is interrupted, the DC link voltage in the inverter decreases. At
an adjustable threshold, kinetic buffering intervenes (V
DC min
control). The V
DC min
control forces
the load to go into slightly regenerative operation. As a consequence, the inverter covers its
power loss and the losses in the motor with the kinetic energy of the load. The load speed
decreases; however, during kinetic buffering, the DC voltage remains constant. After the line
supply returns, the inverter immediately resumes normal operation.
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Figure 6-56 Principle mode of operation of kinetic buffering
Parameter Description
r0056.15 Status word closed-loop control
0 signal V
DC min
controller is not active
1 signal V
DC min
controller is active (kinetic buffering)
p0210 Device supply voltage (factory setting: 400 V)
Advanced commissioning
6.34 Kinetic buffering (Vdc min control)
Converter with the CU230P-2 Control Units
346 Operating Instructions, 09/2017, FW V4.7 SP9, A5E34257946B AE

Siemens CU240B-2 Specifications

General

Brand	Siemens
Model	CU240B-2
Category	Inverter
Language	English