Connecting
5.4 System integration
1FK7 G2 synchronous motors
Operating Instructions, 05/2021, A5E50907562B AA
83
5.4.4
Connecting the holding brake
Direct connection
The holding brake in the motor is directly connected to the SINAMICS converter using
MOTION-CONNECT power cables with integrated brake connecting cable. See Chapter
"Connecting to a converter (Page 79)"
Connection to external power supply
You can also control the holding brake via an external power supply.
The external power supply can be a PELV (PELV = Protective Extra Low Voltage) power supply,
if:
•
Protective separation from the motor winding is guaranteed for the brake cable in the
motor
•
The power cable has reinforced insulation
Note
The relay K1, located between coil and contact, must also have reinforced insulation to
protect the internal logic voltage.
If you control the holding brake via an external power supply, you must protect the holding
brake from voltage peaks with a protective circuit. See figure "Suggested circuit for the
external power supply"
The protective circuit also guarantees the specified switching times, see Chapter "Technical
data of the holding brake_1FK7 (Page 45)".
The motor holding brake requires 24 V ± 10 % at the motor connection in order to reliably
open.
•
Take into account the voltage drops along the supply cable.
•
Use a Control Supply Module (CSM) or a regulated DC power supply, whose setpoint is set
to 26 V.
•
Use power supply cables with a minimum cross-section of 1.5 mm².
•
Calculate the maximum permissible cable length using the following formula.
If the maximum voltage of 24 V DC +10 % is exceeded, then the brake can close again.
You can approximately calculate the voltage drop
Δ
U
for copper cables as follows:
Δ
U
/ V = 0.042 •
x
•
I
Brake
l
/ m = cable length
x
=
l
/
q
q
/ mm
2
= brake conductor cross-section
I
Brake
/ A = brake DC current