EXCEL 10 W7761A INPUT/OUTPUT DEVICE

No installation should be designed where the line loss is greater than two volts to allow for nominal operation if the primary voltage drops to 102 Vac (120 Vac minus 15 percent).

To meet the National Electrical Manufacturers Association (NEMA) standards, a transformer must stay within the NEMA limits. The chart in Fig. 11 shows the required limits at various loads.

With 100 percent load, the transformer secondary must supply between 23 and 25 volts to meet the NEMA standard. When a purchased transformer meets the NEMA standard DC20-1986, the transformer voltage-regulating ability can be considered reliable. Compliance with the NEMA standard is voluntary.

The following Honeywell transformers meet this NEMA standard:

Transformer Type

VA Rating

AT20A

20

AT40A

40

AT72D

40

AT87A

50

AK3310 Assembly

100

SECONDARY VOLTAGE

27

26

25

24

23

22

21

20

19

18

17

16

15

14

050100150200

% OF LOAD

M993

Fig. 11. NEMA class 2 transformer voltage output limits.

Attach earth ground to W7761 Device terminal 1. See Fig. 12, 13 and 14, 16 through 20.

TRIAC`

COMMON

TRANSFORMER

TRIAC LINES` TO ACTUATORS` AND CONTACTORS

W7761A

CONNECT POWER TO `

TERMINALS 24 AND 25

25 24 22 20

1

 

EARTH`

M10089

GROUND

 

Fig. 12. Power wiring details for one Excel 10 per transformer.

22

74-2699

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Honeywell W7761A specifications VA Rating, Nema class 2 transformer voltage output limits