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7-3
Each of the 3 NACs has two pairs of driven outputs (A+/A-, B+/B-) which operate
together.
NAC B outputs have polarity reversal supervision and expect a 10k EOLR. Each
connected device must have a suitably rated blocking diode.
NAC A outputs have an integral 10k to accommodate Class A (loop) wiring. Class A
wiring is not mandatory under AS1670.1.
The 3A max rating applies to each NAC, B + A outputs combined. NAC load current
may be read on the LCD.
The Australian SPS has extra decoupling capacitors fitted to the NAC outputs, and cannot
be used to drive the Simplex range of addressable appliances.
NACs may be programmed to be normally on and the terminals used as power supply
outputs. See the SPS Auxiliary Power Wiring section following.
Review the following guidelines for NACs before you begin NAC field wiring.
• All wiring shall be 0.75 mm
2
to 4 mm
2
.
• All wiring is supervised and power-limited.
• The maximum alarm current is 3 A per circuit. The supervisory current is 2.03
mA at
24 VDC.
• The nominal voltage rating is 24 VDC, 2 V p-p ripple (maximum).
• The total available current from the SPS is 9 A. Any current used for card power
by modules plugged into the PDI, as well as any auxiliary 24 VDC current, must
be deducted from the total 9 A available current.
• Terminal designations “+” and “-” are for the alarm state not the supervision
state.
Continued on next page
SPS NAC Field Wiring Guidelines
Overview
Guidelines