Emerson E2 User Manual download pdf (Page 65)

IMC/Prodigy Rooftop Unit Controllers The RS485 Network and Hardware Setup • 6-5

To select a power transformer for a board or a series of

boards:

1. Determine what the total VA is for the boards

that will be powered by the transformer (see

Table 6-3).

Example: Two MultiFlex 168AOs (15 VA

each), and one 8DO (18 VA) boards are to

be powered by one transformer. The total

VA is:

2. Use a transformer that has a power rating

higher than the total calculated VA (see Table

6-2).

Example: For boards totalling 48VA, a 56VA trans-

former is sufficient, since 56VA is greater than 48VA.

I/O Board Transformers should be located within 10

feet of the board it is powering, preferably within the

board enclosure.

6.1.9.1 Wiring Types

For powering I/O boards, use only the listed wire types

from Table 6-4. Three-conductor non-shielded cables are

the recommended wire for connecting between the center

tapped transformer and the I/O boards. The third conduc-

tor should be connected to earth ground. If boards use a

center-tapped transformer, also connect the center tap to

the earth grounded third conductor.

The wire length from the transformer and the number

of boards connected to the same wire determines the type

wire gauge used. In most cases, the distance between the I/

O boards and the transformer that supplies power to them

is not enough to be concerned with. But it is very impor-

tant not exceed this maximum wire length or the boards

will malfunction.

Use these formulas to determine if the wire gauge you

are using fits within specification:

Sensors requiring 24VAC can be powered from the

same transformer powering the input board as long as the

resulting total load of both the input board(s) and the sen-

sor(s) connected to the transformer does not exceed the

transformer’s VA rating. Consult Section 6.1.9, Powering

the I/O Boards, and Section 8.6.1, Powering Echelon

Devices for more information.

6.1.10 Board Installation

The following pages give step-by-step graphical

instructions on all steps necessary to install each I/O Net-

work device so that it is powered up and able to communi-

cate with E2. If these devices have not yet been mounted,

refer to Section 3.2, Mounting I/O Boards for mounting

instructions for these devices.

6.2 IMC/Prodigy Rooftop

Unit Controllers

All E2 Building Controller (BX) versions 2.21F01 and

Unit Amps VA VAC Center-

tapped?

16AI 0.25 5.0 24 Yes

8RO/SMT 0.75 15.0 24 Yes

4AO 0.5 10.0 24 Yes

8DO 1.5 18 24 Yes

8IO/ARTC 0.75 18 24 No

IRLDS N/A N/A 120/240 N/A

RLDS N/A N/A 120/240 N/A

MultiFlex

ESR

3.3 80 24 Yes

MultiFlex

0.25 6 24 Yes

MultiFlex

88, 88AO,

168, and

168AO

0.75 15 24 No

MultiFlex

1616L,

1616LAO,

1616LDO

1.0 20 24 No

Table 6-3

- Device Power Requirements

2 15VA 1 18VA+ 48VA=

Power Wiring Types

14 AWG Belden 9495

18 AWG Belden 9493

Table 6-4 - Power Wiring Types

14 AWG:

Feet = 1920/VA

18 AWG:

Feet = 739/VA

(VA is the total VA rating of the I/O boards)

For example, if you had an 80 VA load:

14 AWG: 24 ft

18 AWG: 9 ft (rounded down)

Figure 6-3

- Power Wire Lengths

1 2 ... 60 61 62 63 64 65 66 67 68 69 70 ... 272 273

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