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KEB COMBIVERT F5
Name: Basis
18.04.02
6
Abschnitt SeiteDatum
© KEB Antriebstechnik, 2002
All rights reserved
Kapitel
Functional DescriptionProtective Functions
6.7 Protective
Functions
Fig. 6.7.1.a Survey ramp stop function
6.7.1 Ramp Stop and
Hardware Current
Limit
The protective functions protect the inverter against switch off caused by overcurrent,
overvoltage as well as thermal overheating. Furthermore, you can restart the drive
after an error automatically (Keep-On-Running).
The ramp stop function essentially fulfills two tasks. It prevents
• overcurrent errors (E.OC) during the acceleration phase,
• overvoltage and overcurrent errors (E.OC/E.OP) during the deceleration phase,
by stopping the ramp on exceeding adjustable levels. Moreover, the ramp stop function
can be activated by a digital input. Beyond that a hadware current limit is integrated
which intervenes independent of the software and is thus much faster.
Although these functions can be activated in controlled operation, this is to be avoided,
since the KEB COMBIVERT regulates here at the torque limits.
Pn.25 Deceleration stop / DC-voltage
200…800 V
Pn.24 Max. Ramp current
0…200 %
Ramp stop
Pn.22 Ramp stop/Activation
LD-Stop (I) LD-Stop (U) LA-Stop
0 off off off
1 off off on
2 off on off
3 off on on
4 on off off
5 on off on
6 on on off
7on onon
Hardware current limit
LA-Stop The function protects the frequency inverter against switch off caused by overcurrent
during the acceleration phase. The current level is adjustable with Pn.24 in the range
of 0…200 %. The protective function can be deactivated with Pn.22.
During deceleration energy is refed into the frequency inverter, which causes a rise
of the DC-link voltage.
If too much energy is refed the inverter can trip to error OP or OC. If the LD-Stop
function is activated with Pn.22, the DEC-ramp is regulated according to the adjusted
DC-link voltage (Pn.25) or the DC-link current (Pn.24), so that errors are avoided to a
large extent.
The hardware current limit is an additional, fast protection to prevent faults caused by
overcurrent. Upon exceeding the max. short-time current limit (see Power Circuit
Instruction Manual) the hardware current limit becomes active. The following settings
are possible with uF.15:
LD-Stop
The hardware current limit limits the
current at the limit and triggers no
error. This can lead to torque
breakdowns at the motor shaft, which
is especially important during the
operation „lifting and lowering“ since the
drive can sag because of missing torque
without the brake engaging.
see „Digital outputs“
do.0...do.7 value „15“
Pn.23 Input selection
Ramp stop
0...4095 (Default 0)
also see
„Digital inputs)
0 off; Hardware current limit disabled
1 Single phase mode; Hardware current limit enabled; works both in motoric
and generatoric operation
2 Zero vektor mode; Hardware current limit enabled; works only motoric, but at
activated function it makes available more torque. Generatoric operation
switches to Mode 1.
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