Fig. 15 Power Supply Connections For Bkxx50 And Bkxx51; Fig. 16 Ul Identification - Beckhoff BK3 0 Series Documentation

3.4.4.2 BKxx50 and BKxx51
The Bus Couplers / Bus Terminal Controllers require an operating voltage of 24 V
Class 2 power supply to comply with the UL requirements.
The connection is made by means of the upper spring-loaded terminals labelled Us and GNDs. This supply
voltage is used for the electronic components of the Bus Coupler and Bus Terminal Controllers and (via the
K-bus) the electronic components of the Bus Terminals. It is galvanically separated from the field level
voltage.
Fig. 15: Power supply connections for BKxx50 and BKxx51
Fig. 16: UL identification
Note the UL requirements for the power supply.
To comply with the UL requirements, the 24 V
• from an isolated source protected by a fuse of max. 4A (according to UL248) or
• from a voltage supply complying with NEC class 2.
An NEC class 2 voltage source must not be connected in series or parallel with another NEC class 2
voltage source!
No unlimited voltage sources!
To comply with the UL requirements, Us must not be connected with unlimited voltage sources.
BK3xx0
DANGER
supply voltage for Us must originate
DC
DANGER
Version: 4.3.0
Mounting and wiring
. Use a 4 A fuse or a
DC
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