Lenze EVS93 Series, System Manual

Page: 235 / 386

Function library
Function blocks
3.2.62 Mains failure control (MFAIL)
3−207
l
EDSVS9332K−EXT EN 4.0
Fine adjustment
t
U G
t 1
t 2
t
n
0
0
C M P 2 - O U T
M F A I L - D C - S E T
t 3
O p e r a t i n g t h r e s h o l d
S w i t c h - o f f t h r e s h o l d O U
S w i t c h - o n t h r e s h o l d b r a k e u n i t
S w i t c h - o f f t h r e s h o l d L U
Fig. 3−157 Schematic representation with different brake torques
t = t1 Mains failure
t = t2 Zero speed with higher braking torque (short adjustment time)
t = t3 Drive reaches the LU switch−off threshold with lower brake torque (higher adjustment time)
without reaching speed 0
t > t3 Drive is no longer controlled (is braked by friction)
Repeat the following steps several times.
1. Obtain a very low final speed before the controller reaches the undervoltage threshold LU:
– Increase the proportional gain MFAIL V
p
(C0980).
– Decrease the reset time MFAIL T
n
(C0981).
2. Avoid activation of the brake unit or the overvoltage threshold on:
– Increase the reset time MFAIL T
n
(C0981) until the characteristic in Fig. 3−156 is almost
reached.
– Additionally reduce the setpoint of the DC bus voltage at the input MFAIL−DC−SET (in the
example C0472/19), if necessary.