6.6
Electrical brake circuit
During braking with the aid of the motor, energy is fed back to the servo amplifier. This energy is
converted into heat in the brake resistor (
ð
p. 112). The brake resistor is switched into circuit by the
brake circuit. The brake circuit (thresholds) are adjusted to the supply voltage with the help of the
setup software.
Our customer service can help you with the calculation of the brake power which is required. A
is described in the "Product Wiki" which is accessible at
. A
description of the interface can be found on page 48.
Functional description:
1.- Individual amplifiers,
not coupled
through the DC bus link (DC+, DC-)
The circuit starts to respond at a DC bus link voltage of 400V, 720V or 840V (depending on the
supply voltage). If the energy which is fed back from the motor, as an average over time or as a
peak value, is higher than the preset brake power, then the servo amplifier will output the status
“brake power exceeded” and the brake circuit will be switched off. At the next internal check of the
DC bus link voltage (after a few ms) an overvoltage will be detected and the servo amplifier will be
switched off with the error message “Overvoltage F02” (
ð
p. 94).
The BTB/RTO contact (terminal X3/2,3) will be opened at the same time (
ð
p. 67).
2.- Several servo amplifiers
coupled
through the DC bus link circuit (DC+, DC-)
Thanks to the built-in brake circuit with its patented power distribution, several amplifiers (even with
different current ratings) can be operated off a common DC bus link. This is achieved by an auto-
matic adjustment of the brake thresholds (which vary, because of tolerances).
The brake energy is distributed equally among all the amplifiers. The
combined power
of all the
amplifiers is always available, as continuous or peak power. The switch-off takes place as described
under 1. (above) for the servo amplifier with the lowest switch-off threshold (resulting from toleran-
ces).
The RTO (BTB) contact of this amplifier (terminals X3/2,3) will be opened at the same time
(
ð
p. 67).
Brake circuit: technical data
SERVOSTAR
Supply voltage Rated data
DIM
640
670
3 x 230 V
External regen resistor
Ohm
15
10
Upper switch-on level of regen circuit
V
400 - 430
Switch-off level of regen circuit
V
380 - 410
Overvoltage F02
V
450
Continuous power of regen circuit (R
Bext
) max.
kW
6
Pulse power, external (R
Bext
max. 1s)
kW
10
16
3 x 400 V
External regen resistor
Ohm
15
10
Upper switch-on level of regen circuit
V
720 - 750
Switch-off level of regen circuit
V
680 - 710
Overvoltage F02
V
800
Continuous power of regen circuit (R
Bext
) max.
kW
6
Pulse power, external (R
Bext
max. 1s)
kW
35
50
3 x 480 V
External regen resistor
Ohm
15
10
Upper switch-on level of regen circuit
V
840 - 870
Switch-off level of regen circuit
V
800 - 830
Overvoltage F02
V
900
Continuous power of regen circuit (R
Bext
) max.
kW
6
Pulse power, external (R
Bext
max. 1s)
kW
45
70
Suitable external regen resistors can be found in our accessories manual.
SERVOSTAR
®
640/670 Instructions Manual
25
Kollmorgen
12/2010
Technical description
