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6
Kinetic Energy Buffering
The kinetic energy buffering function can be used to decelerate to stop after a sudden power loss using the
kinetic energy of the rotating machine to maintain the DC bus voltage. Thereby an uncontrolled coasting of a
machine can be prevented. The function can be activated using a multifunction input i.e. can be operated by a
DC bus undervoltage alarm output or by a voltage drop relay. A wiring example is shown in Fig. 6.80.
Fig 6.91 Wiring Example for KEB function usage
Related Parameters
Setting the Momentary Power Loss Detection (L2-01)
• L2-01 = 0
The inverter trips with undervoltage fault (UV1).
• L2-01 = 1
No UV1 is detected within the time which is set in parameter L2-02. If this time is exceeded and the power
has not returned, an UV1 fault is output.
• L2-01 = 2
No UV1 is detected. The inverter continues operation as long as the CPU is working.
To use the Kinetic Energy Buffering function in connection with the UV alarm output of the inverter, parame-
ter L2-01 must be set to 1 or 2.
Setting the Undervoltage Level (L2-05)
This parameter sets the voltage level for the DC bus at which a DC bus undervoltage (UV, UV1) is detected.
Normally there is no need to change this setting. If the UV detection is used for activating the Kinetic Energy
Buffering function, the UV detection level should be increased to the maximum to detect the UV as fast as
possible.
Parameter
No.
Name
Factory
Setting
Change
during
Opera-
tion
Control Methods
V/f
V/f with
PG
Open
Loop
Vector
Closed
Loop
Vector
C1-09 Fast stop time 10.0 s No AAAA
L2-01Momentary power loss detection 0 No AAAA
L2-05 Undervoltage detection level
190 V
* 1
* 1. The values are for a 200 V class Inverter. Values for a 400 V class Inverter are double.
No AAAA
L2-08Frequency reduction gain at Kinetic Energy Buffering start. 100 %No AAAA
L1
L2
L3
Voltage drop relay
Terminal S3 to S7
SN
Varispeed F7
H1-=66
to
Motor
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