RHE26/27 Installation & Startup Guide – Doc. No. 8.2.1.06 – Ver. 1.40
11
Power Supply and Grounding
For connections longer than 0.5m shielded cables should be used. For connections longer than
3m, additional ferrite filter beads close to the RHE are recommended for avoiding RF EMI.
The power supply input is protected by a fuse. As a protection against fire in case of a short in
the cable, the supply side of the cable should be protected by a fuse (see figure 5, SI1) with a
rating not higher than the current carrying capacity of the cable.
The cables used for power supply and grounding must comply with the national
requirements. If required, certified cables must be used. The minimum cross section is
0.35mm² (AWG 22) for DC supply cables and 0.5mm² (AWG 20) for mains supply cables.
The RHE26/27 do not contain a mains switch. A switch or circuit breaker close to the
RHE26/27 must be included in the supply line. The switch must be marked correspondingly.
3.2.2.1
Grounding
RHE26 and RHE27 transmitters must be grounded. Ground the RHE by either connecting a
ground to terminal 22 (PE) or to the M4 screw type terminal on the back of the case. The cross
sectional area of the grounding wire must be equal to or larger than the conductors used for any
supply or I/O connection.
Note
: National and Local electrical code requirements may contain additional grounding
requirements. Please ensure that all grounding to carried out to these [legal] requirements.
3.2.2.2
12V to 24V DC Power Supply
Units for use with a DC power supply (order
code options D1 and U1) require a regulated DC
supply voltage of 12V or 24V. They will operate
with a power supply in the range 10V to 28V.
Connect the positive supply to terminal 20 and
0V to terminal 21.
Terminals 21 (0V) and 22 (PE) are connected via
a 1kΩ resistor. The resistor can withstand a
potential difference of up to 30V between 0V
and PE, but voltage differences above 5V should
be avoided.
3.2.2.3
100V to 240V AC Power Supply
Units for use with an AC power supply (options
A1 and U1) will operate with any AC supply with
nominal 100V to 240V, 50H to 60Hz. Voltage
limits are 90V to 264V.
Connect the live or hot wire (L) to terminal 23
and the neutral wire (N) to terminal 24.
The AC supply terminals are completely
isolated from PE (terminals 10, 22, 68) and GND
(terminals 21, 37, 57).
Figure 5: DC Power Supply
Figure 6: AC Power Supply
