Siemens MASTERDRIVES MC 1FK7 Configuration Manual page 89

Fig. 4-6
Important information and instructions when installing the connecting cable
The brake connecting cable is included in the power cable. The insulation between the power
and brake connection is dimensioned for the basic insulation (VDE 600 V/1000V UL). The
relay K1, located between the coil and contact, must also have basic insulation in order to
protect the internal logic voltage (PELV=Protective Extra Low Voltage). The PELV supply may
not be used to supply the holding brake (refer to Fig. "Recommended circuit for the external
power supply with protective circuit").
Determining the minimum voltage
The minimum voltage of 24 V DC -10% must be available at the connector on the motor side
in order to guarantee that the brake reliably opens. If the maximum voltage of 24 V DC +10 %
is exceeded, then the brake could re-close. The voltage drop along the brake feeder cable
must be taken into consideration.
The voltage drop for copper cables can be approximately calculated as follows:
dV = 0.042 • (l/q) • I
l= cable length in m
q= brake conductor cross-section in mm
I
brake
dV= voltage drop along the brake cable in V
1FK7 Synchronous Motors
Configuration Manual (PFK7), 10/2005 Edition, 6SN1197-0AD06-0BP1
Terminology (time) for holding operation
brake
= DC current of the brake in A
2
Motor Components (Options)
Holding brake
4-13