Siemens MICROMASTER 440 Operating Instructions Manual page 207

Issue 10/06
The advantages of dynamic resistor braking include:
The regenerative energy is not converted into heat in the motor
It is significantly more dynamic and can be used in all operating states (not only
when an OFF command is output)
~
Fig. 3-76
The braking energy in the DC link is converted into heat when dynamic braking is
activated (enabled using P1237). The energy is converted into heat using the
voltage-controlled chopper resistor (ballast resistor). Chopper resistors are used if
regenerative energy is dissipated in the DC link for a short time, e.g. when a drive
brakes and the drive should be prevented from being shutdown (tripped) with fault
message F0002 ("DC link overvoltage"). In this case, when the DC link threshold
V
DC chopper
switch (semiconductor switch).
Switch-in threshold of the chopper resistor:
If P1254 = 0 :
Otherwise :
The chopper switch-in threshold V
P1254 (Auto detect V
voltage P0210 or indirectly using the DC link voltage and r1242.
V
DC, act
V
DC, Chopper
∆
V
Fig. 3-77
MICROMASTER 440 Operating Instructions
6SE6400-5AW00-0BP0
MM4
=
~
Connecting the chopper (braking) resistor
is exceeded, then the chopper resistor is switched-in using an electronic
=
V
DC , Chopper
=
V
DC , Chopper
switch-on levels), either directly using the line supply
DC
100 %
∆V
–
V
1
0
P1237
Duty cycle
monitoring
Mains
200 - 240 V 380 - 480 V
9.8 V 17.0 V
Mode of operation of the dynamic braking
Chopper resistor
B+ B-
=
Chopper
control
⋅ ⋅ =
. 1 13 2 V . 1 13
line sup ply
⋅
. 0 98 r 1242
is calculated as a function of parameter
DC chopper
0
x
1
1
Alarm
A0535
0
500 - 600 V
21.3 V
3 Functions
~
⋅ ⋅
2 P 0210
x
t
= ⋅
t
Chopper, ON Chopper
100
207