Operation Manual

5-7
IM 1F5B2-01E
5. WIRING
5.6 Power Supply Voltage and Load Resistance
Analog Output
■ ULTRA YEWFLO uses two-wire transmission and, therefore, the cable is used both
as the power supply line and as a signal line. A DC power supply is needed for the
transmission loop line. (The distributors listed in Table 5.6 are available from
Yokogawa Electric. Contact the manufacturer as necessary.)
■ The maximum communicable distance over a transmission cable is 2 km when a
CEV cable is used.
■ Communication via the amplifier board is always possible irrespective of the wiring
conditions.
Table 5.6 Distributors
ledoM
foepyT
noitalusnI
otylppuSrewoP
rotubirtsiD
forebmuNelbatcennoC
s'OLFWEYARTLU
foecnatsiseRmumixaM
eriWgnitcudnoC
011-TBDS
012-TBDS
041-SBDS
detalusni-pooL
detalusni-O/I
detalusni-pooL
derewop-CD/CA
derewop-CD/CA
derewop-CD/CA
1
1
4
053 Ω
053 Ω
053 Ω
• When configuring a loop, make sure the load resistances of both instruments, such as
a distributor, and conducting wires, which are to be installed in the loop, fall within
the shaded area of Figure 5.6-1.
• The load resistance should preferably be connected to the negative-polarity terminal
of the power supply if no distributors are used. Figure 5.6-2 shows an example of
connection between ULTRA YEWFLO and a distributor.
R=
E–10.5
0.0236
250
600
10.5 16.4 24.7
30 42
Power Supply Voltage E (V)
Communicable
range
Load resistance R (Ω)
Note: In the case of CENELEC intrinsic safety, the power supply voltage shold be under 30 VDC.
Figure 5.6-1 Relationship Between Power Supply Voltage and Load Resistance
(Analog Output)