Preventing Overvoltage During Deceleration - Omron VARISPEED F7 User Manual

Preventing Overvoltage During Deceleration

The stall prevention during deceleration function lengthens the deceleration time automatically with respect to
the DC-bus voltage to avoid overvoltage tripping.
Related Parameters
Parameter
No.
Stall prevention selection during deceleration function selec-
L3-04
tion
Setting the Stall Prevention Selection During Deceleration (L3-04)
There are four different settings selectable for L3-04.
L3-04=0: Disabled
This setting disables the stall prevention function during deceleration. The motor will be deceler-
ated using the time set in C1-02 (C1-04/06/08). If the load inertia is very high and an OV fault
occurs during deceleration a Braking option has to be used or the time has to be lengthened.
L3-04=1: Enabled
This setting enables the stall prevention during deceleration. The inverter tries to decelerate within
the set deceleration time. It also observes the DC bus voltage. If the DC bus voltage reaches the
stall prevention level the deceleration is stopped and the output frequency is held. When the DC bus
voltage falls below the stall prevention level the deceleration will be continued.
L3-04=2: Intelligent deceleration
This setting enables the stall prevention during deceleration. The deceleration time set as C1-
taken as reference. The function automatically tries to optimize the deceleration time by observing
the DC bus voltage and shortening the deceleration time. The function does not lengthen the decel-
eration time, i.e. if C1-
L3-04=3: Enabled with braking resistor
This setting enables the stall prevention during deceleration using a braking option. It works similar
to setting 2, the only difference is that a braking option is used. The deceleration time set in C1-
is also disregarded.
This setting is not available in Closed Loop Vector Control, please select L3-04=0 instead.
Factory
Name
Setting
is set too short OV may occur.
Control Methods
Change
during
V/f with
Opera-
V/f
PG
tion
1 No Q Q
Open Closed
Loop Loop
Vector Vector
Q Q
6
is
25
6-