Voltage Drop Considerations - Honeywell SEC-H-602 Manual

Power Estimate Examples
Two example estimates are provided here, as follows:
• System 1, 8 door readers
• System 2, 10 door readers
SYSTEM 1, 8 DOOR READERS
This system requires 8 door readers and additional IO
points requiring one SEC-H-RIO/U module. Two readers
attach to the Security Controller, the other 6 readers
require 3 SEC-H-R2R/U modules (2 readers each). All
readers draw 0.04A maximum, such that power/battery
calculations (Table 2) factor this in.
• Min. power supply (W) = 7.2W + (3 x 1.7W) + (1 x
6.0W) = 7.2W + 5.1W + 6.0W = 18.3W
• Min. backup battery (Ah) = 2.40Ah + (3 x 0.56Ah) + (1
x 2.0Ah) = 2.4Ah + 1.68Ah + 2.0Ah = 6.08Ah
In this case, a single 30W Enclosure Power Supply
provides ample reserve, and the equipment could be
housed in two enclosures as follows:
• SEC-ENC-H-2/U (large): Security controller, one SEC-
H-RIO/U module, two SEC-H-R2R/U modules.
• SEC-ENC-H-3/U (small): one SEC-H-R2R/U module.
The sealed lead acid Backup Battery in this case might be
two 12V 7.0Ah types in parallel, providing 14.0Ah total.
Between the two Security Enclosures, module assemblies
are wired together using 3-conductors for power/backup
battery ("PS-", "PS+", "BB").
SYSTEM 2, 10 DOOR READERS
The system requires 10 door readers and additional IO
points requiring two SEC-H-RIO/U modules. Two readers
attach to the Security Controller, the other 8 readers
require 4 SEC-H-R2R/U modules (2 readers each).
Readers draw 0.13A maximum, such that power/battery
calculations (Table 2) factor this in.
• Total min. power supply (W) = 10.0W + (4 x 5.0W) + (2
x 6.0W) = 10.0W + 25.0W + 12.0W = 42.0W
• Min. backup battery (Ah) = 3.33Ah + (4 x 1.67Ah) + (2
x 2.0Ah) = 3.33Ah + 6.68Ah + 4.0Ah = 14.01Ah
Gauge
(AWG) 0.10A
10
0.020
12
0.032
14
0.050
16
0.080
18 0.127
20
0.202
22 0.320
See Table 2 for "worst case" amps used by SEC-H-R2R/U
and SEC-H-RIO/U modules, using two different reader
types (readers draw either 0.13A or 0.04A each).
Table 3. Voltage Drop Per 100 Feet Run (30m) of Paired Wire.
0.25A 0.5A
0.05 0.10
0.08 0.16
0.13 0.25
0.20 0.40
0.32 0.64
0.50 1.01
0.80 1.60
SEC-H-602 AND SEC-H-616 SECURITY CONTROLLER
Assuming that all equipment is located relatively nearby, it
could be housed in two large enclosures. The security
controller is powered by its integral power supply. The
second enclosure is powered by a battery-backed 3rd
party power supply.
• SEC-ENC-H-2/U A (large): Security controller, one
SEC-H-RIO/U module, two SEC-H-R2R/U modules
(26W).
• SEC-ENC-H-2/U B (large): One SEC-H-RIO/U, two
SEC-H-R2R/U (16W).
NOTE: If the SEC-H-R2R/U and/or SEC-H-RIO/U
expansion modules are mounted in remote
locations from the Security Controller and its
backup batteries, or if a large system with
multiple local power supplies, additional fac-
tors apply. See the next sections "Voltage
Drop Considerations" and "Maximum Output
Load Considerations."

Voltage Drop Considerations

When using an Enclosure Power Supply and backup
battery to power the Security Controller plus all expansion
modules, and some modules are not mounted in the
same enclosure with the Security Controller, you must be
aware of voltage drops in the connecting "trunk power"
cabling. Typically, this applies only if modules are located
in different locations—that is, not in the same enclosure or
in adjacent enclosures.
NOTE: The 15Vdc power supply and the backup bat-
tery(ies) charged by the Security Controller
must always be located in the same Security
Enclosure as the Security Controller.
Undersized selection of cabling can result in unacceptably
high voltage drops, and expansion modules/attached
readers may not operate correctly—especially during
emergency (battery backup) operation.
The maximum allowable voltage drop due to wiring is
1.5V. This equates to the difference in voltage measured
across the PS+ and PS- at the source SEC-ENC-H-1/U or
SEC-ENC-H-2/U enclosure power supply, and the PS+
and PS- at the furthest non-powered Security Enclosure
that houses an expansion module. Or, when powered by
battery backup, the difference in voltage measured across
the BB and PS- at the enclosure with the Security
Controller, and the BB and PS- at the furthest WEBs-AX
Security Enclosure.
Table 3 provides a voltage drop chart, showing voltage
drops per 100 feet of paired wire of different gauges
(AWG), at different load amps. Also see "Connection
Overview" on page 13.
Load Current
1.0A 1.5A
0.20 0.30
0.32 0.48
0.50 0.75
0.80 1.20
1.27 1.91
2.02 3.03
3.20 4.80
For an example, consider in the previous System 2, 10
door readers, that two of the four SEC-H-R2R/U modules
are mounted remotely in locations 500 feet (366m) away.
7
2.0A 4.0A
0.40 0.80
0.64 1.27
1.01 2.02
1.60 3.20
2.54 5.08
4.03 8.07
6.40 12.81
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