Echelon LONWORKS PLT-22, User Manual

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Example 2: Line-to-Neutral, Transformer-Isolated Coupling Circuit
Figure 4.11 presents a schematic for a line-to-neutral, transformer-isolated coupling
circuit. Table 4.5 lists component values and recommended suppliers/part numbers for
coupling to AC mains with a nominal line voltage in the range 100-240VAC. For
coupling to AC mains with a nominal line voltage in the range of 100-120VAC, refer to
table 4.6. This schematic may also be used for coupling to wiring other than AC mains
with AC or DC voltages of 250V
RMS
or less or for coupling to an unpowered wire pair.
Transmit Amp
Receive
Front
End
PLT-22
C1
C2
T1
TXOUT
RXIN
RXCOMP
L3
Line
Neutral
D1
R1
PROTECT
F1
L4
C4
R2
C3
V
A
See
note
below
Note: This optional circuit should be added to nodes with a nominal VA<12V or nodes that contain a
triac or SCR load switching device.
Figure 4.11 L-to-N, Transformer-Isolated Coupling Circuit Schematic
For long haul operations ( ≥ 300m) on lightly loaded lines communication distance
can be maximized by installing a termination circuit at each end of the cable.
Examples include unpowered twisted pair networks, low voltage networks, and
dedicated mains networks with minimal loading at the communication frequency of
the transceiver. A recommended termination circuit is shown in figure 4.12.
100ž, 1/4W, ±5%
0.47µF, ±20%, non-polarized (voltage
rating must be suitable for application)
Figure 4.12 Termination Circuit
4-20 Coupling Circuits