Mounting and wiring
BK3xx0
27
Version: 4.3.0
3.4.4.2
BKxx50 and BKxx51
The Bus Couplers / Bus Terminal Controllers require an operating voltage of 24 V
DC
. Use a 4 A fuse or a
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
DANGER
Note the UL requirements for the power supply.
To comply with the UL requirements, the 24 V
DC
supply voltage for Us must originate
• 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!
DANGER
No unlimited voltage sources!
To comply with the UL requirements, Us must not be connected with unlimited voltage sources.
