Emerson E2 operation manual Wiring Types

Emerson Retail Solutions supplies a wide variety of 24VAC transformers with varying sizes and either with or without center taps. Table 6-2shows the transformer sizes and whether they are center-tapped or non-center-tapped.

Table 6-3lists each board, the board’s rating, and whether or not the board must use center-tapped power.

Xformer P/N	VA Rating	Input Voltage	Center Tap?
640-0041	50 VA	110 VAC	No
640-0042	50 VA	220 VAC	No
640-0056	56 VA	Multi-tap (120/208/240 VAC)	Yes
640-0050	75 VA	110 VAC	No
640-0045	75 VA	220 VAC	No
640-0080	80 VA	Multi-tap (120/208/240 VAC)	Yes

Table 6-2- Transformers Compatible with I/O Network Boards

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	3.3	80	24	Yes
ESR
MultiFlex	0.25	6	24	Yes
16
MultiFlex	0.75	15	24	No
88, 88AO,
168, and
168AO
MultiFlex	1.0	20	24	No
1616L,
1616LAO,
1616LDO

Table 6-3- Device Power Requirements

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 × 15VA ) + (1 × 18VA ) = 48VA

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.

6.1.9.1Wiring 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.

Power Wiring Types

14 AWG	Belden 9495
18 AWG	Belden 9493

Table 6-4- Power Wiring Types

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 import- ant not exceed this maximum wire length or the boards will malfunction.

The I/O Network The RS485 Network and Hardware Setup • 6-5