Emerson MultiFlex RTU, Инструкция по установке и эксплуатации

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Powering the MultiFlex RTU Board Mounting and Powering • 5
A center-tapped transformer may power both
center-tapped and non-center-tapped devices at
the same time, as long as none of the
non-center-tapped MultiFlex boards are old-
style MultiFlex boards. If an old-style
MultiFlex shares the same center-tapped
transformer as a device that uses the center tap,
the old-style MultiFlex will be damaged. Figure
2-5 shows how to wire a non-center tapped
device to a center-tapped transformer.
In addition, the MultiFlex RTU boards can be
powered by one of the 50VA or 75VA
non-center-tapped transformers listed in
Table 2-
1 on page 3
.
Figure 2-6
shows how to wire the
transformers to the MultiFlex boards.
You may also tie one side of the secondary (but
not BOTH sides) to an earth ground, provided
none of the boards powered by the same
transformer are old-style MultiFlex board (see
Section 2.3.2.2. ).
2.3.2.2. Old-Style MultiFlex RTU Boards
No Isolated Power
Supply)
Like the new-style MultiFlex board, the old-
style MultiFlex board can be connected to any of
the center-tapped transformers mentioned in
Table 2-2 , provided you follow the following
three rules:
Rule 1: Ground the 0V terminal on the old-
style MultiFlex board to an Earth ground.
Do not connect the center tap of the transformer
to the 0V terminal.
Rule 2: Do not power an old-style MultiFlex
non-center-tapped board with a transformer
that is also powering a center-tapped device.
This means you cannot connect an old-style
MultiFlex non-center-tapped board to a
transformer that is powering a MultiFlex 16,
16AI, 8RO, 4AO, 8DO, or any previous
generation Emerson board that uses center-
tapped power. Doing so will destroy the
MultiFlex board.
Figure 2-5 - Wiring Non-Center Tapped MultiFlex Boards to
Transformers With a Center Tap
Figure 2-6 - Non-Center-Tapped Transformer Wiring