3
ANTRIEBSTECHNIK
6
7
3
KEB COMBIVERT F4-C
Name: Basis
12.03.99
6
Keep on Running Functions
©
KEB Antriebstechnik, 1997
All Rights reserved
Functional Description
Section
Page
Date
Chapter
6.7
Keep on Running
Functions
Picture 6.7.1.a
Survey of ramp stop functions
6.7.1
Ramp Stop and
Hardware Current
Limit
The protective functions protect the inverter against switch off due to overcurrent,
overvoltage as well as thermal overheating. Furthermore, you can restart the drive
automatically after an error (Keep on Running).
Pn.6 Deceleration stop / DC-voltage level
200…800 V
Pn.5 Ramp stop / Current level
10…199 % (200 = off)
uF.16 Hardware curent limiting
off = 0; 1 und 2 = on
Hardware current limiting on
exceeding the maximum short-
time limit current (see instruction
manual of power circuit)
Ramp stop
Pn.4
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
7
on
on
on
see „Digital Inputs Chap. 6.3.10“
Hardware Current Limit
LA-Stop
This function protects the frequency inverter against switch off due to overcurrent
during the acceleration phase. The current level is adjustable with Pn.5 in the range
of 10…199 %. The protective function is deactivated with Pn.4.
During deceleration energy is fed 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.4 the DEC-ramp is regulated according to the adjusted
DC-link voltage (Pn.6) or the DC-link current (Pn.5), so in many cases errors are
avoided.
The hardware current limit (HWSG) is an additional, fast protection for the prevention
of overcurrent errors. It is activated on exceeding the maximum short-time limit current
(chapter 2.1.6 and 2.1.7). With uF.16 following adjustments are possible:
- 0 (off) hardware current limit switched off
- 1 (on) hardware current limit activated; works in motor as well as in generator
operation
- 2 (on) hardware current limit activated; works only in motor operation, but
with active function it supplies more torque
LD-Stop
The ramp stop function serves mainly two purposes. By stopping the ramp on
exceeding the adjustable levels, it prevents
- overcurrent error (E.OC) during the acceleration phase
- overvoltage and overcurrent error (E.OC/E.OP) during the deceleration phase,
Moreover, the ramp stop function can be activated by a digital input. The hardware
current limit works independent from the software, it can therefore work much faster.
The response of the hardware current
limit initiates no error, that can lead
to torque dips at the motor shaft. This
is of particular importance for the
operation „Hoisting and lowering“, since
the drive can sack due to missing torque
without engagement of the brake.
see „Digital Outputs“
do.1...do.4 „Value 9“
