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5-3
Each of the three NACs on the SPS 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. EOLRs are supplied fitted to
the NAC terminals.
NAC A outputs have an integral 10k to accommodate Class A (loop) wiring. Class A
wiring is not mandatory under AS1670.1.
Class B (string) wiring can only have one branch.
The 3A max rating applies to each NAC, B + A outputs combined under alarm
conditions. NAC load current may be displayed 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 (Strobes).
NACs may be programmed to be normally on to allow the terminals to be 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 must 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 mA
at 24 VDC.
• The nominal supply voltage rating is 24 VDC, 2 V p-p ripple (maximum).
• The total available current from the SPS is 9A. 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 9A available current.
• Terminal designations “+” and “-” are for the Alarm state (ON), not the
supervision state.
The configuration templates supplied for use with the 4100U-S1 all have these default
assignments of the NAC outputs, with corresponding Custom Control equations.
• NAC1 : Ancillary Control Facility (ACF), to control ancillary devices
during an Alarm. This output can be isolated using the ACF Isolate
control on the keyboard.
• NAC 2 : Fire Bell, to operate a bell as required by AS4428.1. This output
can be isolated using the Bells Isolate control on the keyboard.
• NAC 3 : Warning System, to operate devices such as T-Gen 50. This output
can be isolated using the Warning System Isolate control on the
keyboard.
Continued on next page
SPS NAC Field Wiring Guidelines
Overview
Guidelines
Allocations