CPC MultiFlex PAK, Руководство пользователя

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4 • MultiFlex I/O Board Operator’s Guide 026-1712 Rev 3 03-JAN-2008
2.3.1. Choosing Transformer Sizes
In most site installations, a single trans-
former will power multiple devices. Choose a
transformer with a VA rating large enough to
power all devices that will be attached to it.
Table 2-2 gives the VA ratings of the MultiFlex
board products. Refer to your site controller’s
manual for VA ratings of the other I/O boards
that may be powered by one of these transform-
ers.
2.3.2. MultiFlex Combination Input/
Output Board Power Wiring
The MultiFlex PAK boards do not use a cen-
ter tap. Instead, the 0V terminal on the board
should be connected to a separate Earth ground.
Important! The rules that must be fol-
lowed when connecting a MultiFlex PAK
board to a transformer are different depend-
ing on whether you have a "new style" Multi-
Flex board with an isolated power supply (all
MultiFlex boards shipped after November 1,
2002) or an "old style" MultiFlex board (all
MultiFlex boards shipped before November
1, 2002).
A new-style MultiFlex PAK board has a
green power LED located next to the 24VAC
connection terminal in the upper right corner of
the circuit board (see
Figure 2-4 for reference).
If there is a power LED next to the connec-
tor, your MultiFlex is a new-style MultiFlex --
refer to Section 2.3.2.1., New-Style MultiFlex
Combination I/O Boards (with Isolated Power
Supply)
for power wiring instructions.
If there is no power LED next to the connec-
tor, your MultiFlex is an old-style MultiFlex --
refer to Section 2.3.2.2., Old-Style MultiFlex
Combination I/O Boards (No Isolated Power
Supply)
for power wiring instructions.
2.3.2.1. New-Style MultiFlex Combina-
tion I/O Boards (with Isolated
Power Supply)
The new-style MultiFlex board can be con-
nected to any of the center-tapped transformers
mentioned in
Table 2-2 , provided the 0V termi-
nal of the board is connected to an Earth ground.
Unit VA VAC Center
tapped?
MultiFlex PAK,
CUB, RTU,
and RCB
15 24 NO
MultiFlex 16 6 24 Yes
MultiFlex 88,
88AO, 168,
168AO and
168DO
15 24 NO
Table 2-2 - Device Power Requirements
Figure 2-4 - New-Style vs. Old-Style MultiFlex Board
POWER LED
New Style
MultiFlex Board
(Top Left Corner)
NO POWER LED
Old Style
MultiFlex Board
(Top Left Corner)
24 VAC
24 VAC