Secutron MR-2900 Installation Manual page 25

Style Z (Class A) Bell Circuit
MR-2937
"Class A"
Converter
Figure 22: Style Z (Class A) Bell Circuit
Wiring
Note: The inrush current of some devices may cause the current to exceed the 1.5A current limit
momentarily.
Table 4: Maximum Wire Lengths for Bell Circuits
250 mA
12 AWG 1220m (4000 ft)
14 AWG 732m (2400 ft)
16 AWG 457m (1500 ft)
Relay Connections
Figure 23: Relay
Auxiliary Power Circuits
Figure 24 Auxiliary Power Connections
Regulated 24 FWR
500 mA 750 mA
610m (2000 ft) 407m (1300 ft)
366m (1200 ft) 244m (800 ft)
229m (750 ft) 152m (500 ft)
Unused relays are left unconnected. General Purpose Relays and System
Relays operate identically and are wired the same (see Figure 23).
All relay wiring is unsupervised. The general purpose relays (Function
Relays 1-4) have a power factor of .35, power-limited at .6A @ 30VAC/2.0A
@ 30VDC. The Alarm, Supervisory, and Trouble relays have a power factor
of .35, power-limited at .5A @ 30VAC/1.0A @ 24VDC.
The auxiliary power circuits provide 24 VDC for external
devices. The polarity of the circuits is shown in Figure 24.
The Control Unit does not interrupt this circuit. For the wiring
to be power-limited and supervised an end-of-line relay (Part
number PAM-3) must be used. The relay is a 24VDC coil
with 3A contacts.
This is a 4-wire Style Z (Class A) power-limited and
supervised signalling (notification appliance) circuit.
Devices are connected as illustrated in Figure 22.
Maximum wire lengths are shown in Table 4. This is
for the total length of wire, from the panel to furthest
device and back to the panel. Use only approved
devices. Return wiring must be in a separate conduit.
1.0 A
305m (1000 ft)
183m (600 ft)
114m (375 ft)
MR-2900 Installation Manual
1.25 A 1.50 A
244m (800ft) 203m (667ft)
146m (480ft) 122m (400ft)
91m (300ft) 76m (250ft)
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